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Biocompatible, Hemocompatible and Antibacterial Acylated Dextran-g-polyisobutylene Graft Copolymers with Silver Nanoparticles
Cong-Lei Zhao, Yu-Zhuang Gao, Meng-Ying Wu, Hang-Tian Zhang, Yi-Xian Wu
Corrected proof , doi: 10.1007/s10118-021-2621-0
The novel amphiphilic acylated dextran-g-polyisobutylene (AcyDex-g-PIB) graft copolymers with different branch lengths (Mn,PIB, 2600–5800 g/mol) and grafting numbers (GN, 5–28 per 1000 Dex monosaccharide) were successfully synthesized via the nucleophilic substitution of the hydroxyl (―OH) side groups along AcyDex backbone by the living PIB-THF4+ chains prepared through cationic polymerization. The crystallization of AcyDex backbone in AcyDex-g-PIB graft copolymers was confined due to the presence of PIB branches and the morphology changed from short rod-like crystals to fragment-like crystals with increasing Mn,PIB and GN. The obvious microphase separation occurred due to the incompatibility between hard AcyDex backbone and soft PIB branches. AcyDex-g-PIB graft copolymers exhibit excellent biocompatibility towards HeLa cells and good hemocompatibility with red blood cells (RBCs), both of which increase with increasing GN. The increases of water contact angle and roughness on the surface of the graft copolymers with increasing Mn,PIB and GN manifest the anti-protein adsorption performance. The amphiphilic AcyDex-g-PIB graft copolymers could self-assemble in aqueous solution into nanospheres, which can be used as pH-sensitive drug carriers and can release 100% of the loaded drug within 72 h at pH=7.4. AcyDex-g-PIB graft copolymers bearing silver nanoparticles (Ag-NPs, 0.8 wt%–3.9 wt%, 4.5–9.5 nm) show good antibacterial properties. This kind of amphiphilic graft copolymer would have a promising prospect in biological and medical fields.
Micro-Macro Scale Relationship in Creep Deformation of Ultra High Molecular Weight Polyethylene
Bi-Jin Xiong, Zhen-Xian Chen, Jian Kang
Corrected proof , doi: 10.1007/s10118-021-2628-6
Macroscopic and microscale creep deformations of UHMWPE were investigated by using in situ SAXS. A methodology for the measurement of the local creep deformation of inter-lamellar amorphous phase has been proposed. The local strain of inter-lamellar amorphous phase (\begin{document}$ {\varepsilon }_{\rm{a}} $\end{document}) and macroscopic strain (\begin{document}$ {\varepsilon }_{\rm{macro}} $\end{document}) were evaluated and they were compared to study the relationship between macroscopic and microscale creep deformation of UHMWPE. Both of them exhibit two deformation regions against creep time. The entanglements show a strong impact on both the macroscopic and local inter-lamellar amorphous phase creep behavior and they can be well correlated to the molecular weight between two entanglements estimated from strain-hardening modulus. Compared to the macroscopic creep deformation, local inter-lamellar amorphous layers have a smaller creep deformation. From the local creep measurement, the apparent modulus of inter-lamellar amorphous phase can also be estimated (200 < Ma < 500 MPa). These values are much higher than the Young’s modulus of bulk amorphous PE, which can be well explained by the confinement of the lamellar stacks and the enhancement of the amorphous phase with the relatively high concentration of entanglements. This study provides a useful means and quantitative data for achieving the scale transition between the micro and the macro structural levels for the study of viscos-elastic deformation.
Self-healing Hydrogels and Underlying Reversible Intermolecular Interactions
Meng Wu, Qiong-Yao Peng, Lin-Bo Han, Hong-Bo Zeng
Corrected proof , doi: 10.1007/s10118-021-2631-y
Self-healing hydrogels have attracted growing attention over the past decade due to their biomimetic structure, biocompatibility, as well as enhanced lifespan and reliability, thereby have been widely used in various biomedical, electrical and environmental engineering applications. This feature article has reviewed our recent progress in self-healing hydrogels derived from mussel-inspired interactions, multiple hydrogen-bonding functional groups such as 2-ureido-4[1H]-pyrimidinone (UPy), dynamic covalent bonds (e.g., Schiff base reactions and boronic ester bonds). The underlying molecular basics of these interactions, hydrogel preparation principles, and corresponding performances and applications are introduced. The underlying reversible intermolecular interaction mechanisms in these hydrogels were investigated using nanomechanical techniques such as surface forces apparatus (SFA) and atomic force microscopy (AFM), providing fundamental insights into the self-healing mechanisms of the hydrogels. The remaining challenging issues and perspectives in this rapidly developing research area are also discussed.
Dynamic Oxime-Urethane Bonds, a Versatile Unit of High Performance Self-healing Polymers for Diverse Applications
Luzhi Zhang, Zhengwei You
Corrected proof , doi: 10.1007/s10118-021-2625-9
Oxime-urethane bond featuring with high reversibility even at room temperature and multiple reactivity is an emerging dynamic covalent bond, and has shown great potential for self-healing polymers, which are one of the most attractive development directions for next generation of polymeric materials. In this review, recent progresses on the oxime-urethane-based self-healing polymers, including their designs and applications in diverse fields such as biomedicine, flexible electronics, soft robots, 3D printing, protective materials, and adhesives, are summarized, and outlooks on the future development of this field are discussed.
Strong, Removable, and Photoluminescent Hyperbranched Polyamide-amine Hot Melt Adhesive
Si-Jia Zhang, Xing-Xing Chen, Chen-Hui Cui, Li Ma, Qian-Yun Zhong, Kai-Xiang Shen, Jing Yu, Zhen Li, You-Shen Wu, Qiang Zhang, Yi-Long Cheng, Ling He, Yan-Feng Zhang
Corrected proof , doi: 10.1007/s10118-021-2630-z
The development of adhesive technology is gaining increasing attention in machinery, electronics, aviation, and other fields. However, traditional adhesives are difficult to be peeled and removed after cross-linking and curing due to the limited solubility in common solvents, which causes pollution and damage to the surface of the adherend. In this work, we synthesized random hyperbranched polyamide-amine hot melt adhesives through Michael addition of 1,8-octanediamine and N,N'-methylene diacrylamide (ODA-RHP HMA). Owing to the presence of various polar groups, ODA-RHP HMA exhibited robust lap shear strength to different substrates, including glass (6.6 MPa), ceramics (10.3 MPa), steel (11.5 MPa), and aluminum (11.8 MPa). Due to the hydrogen bonds in ODA-RHP, the HMA demonstrated intrinsic self-healing ability, which can be used repeatedly when being subjected to cyclic heating and cooling. Since ODA-RHP HMA can be swollen or dissolved in ethanol, the adhesives can be easily removed through erasing. In addition, ODA-RHP exhibited aggregation-induced luminescence due to the tertiary amine structure in the molecular structure of ODA-RHP, which can be used in the field of cultural relics restoration.
The Anion Binding Affinity Determines the Strength of Anion Specificities of Thermosensitive Polymers
Lei-Lei Lian, Si-Yuan Xu, Hai-Yang Yuan, Guang-Ming Liu
Corrected proof , doi: 10.1007/s10118-021-2633-9
In this work, we demonstrate that the strength of anion specificities of thermosensitive polymers is determined by the affinity of direct anion binding to the polymers. We have prepared a series of thermosensitive statistical copolymers with distinct thermoresponsive behaviors. The anions can specifically interact with the different types of thermosensitive polymers in very different strengths. A similar strength of specific anion effects on thermoresponsive behaviors can be observed at very different salt concentrations for the different types of thermosensitive polymers. A stronger anion binding to the thermosensitive polymers gives rise to a more obvious anion specificity and vice versa. The work presented here opens up opportunities for the application of ion binding affinity to modulate the strength of ion specificities of thermosensitive polymers.
Self-healing Ionic Liquid-based Electronics and Beyond
Shenglong Liao, Xiaodong Lian, Yapei Wang
Corrected proof , doi: 10.1007/s10118-021-2627-7
Owing to the advantages of non-volatility, outstanding fluidity and easy recyclability, ionic liquid-based electronics, such as thermometer, strain sensors and thermoelectric converters, have been growing as attractive alternatives to traditionally solid electronics. The fluidic character endows the ionic liquid-based circuit with self-healing ability, satisfying the needs of longer lifetime and less waste generation for electronics, while at the same time brings the risk of leakage. Avoiding the leakage without sacrifice of self-healing ability is one of the major challenges for constructing ionic liquid-based electronic devices. In this feature article, we summarize our recent progresses in developing two types of self-healing electrical devices based on ionic liquids with little risk of leakage. One type involves the encapsulation of ionic liquids in self-healing polymers, and the other type uses ionic polymers or free-standing ionic liquids which are successfully formulated as intrinsically conductive, self-healing, and recyclable electronic devices without additional encapsulation. In the end, a comprehensive outlook is prospected for the future development of ionic liquid-based self-healing electronics, which is expected to spur more innovative work in this field.
Structural Manipulation of Aminal-crosslinked Polybutadiene for Recyclable and Healable Elastomers
Zheng-Hai Tang, Hui Zeng, Si-Qi Wei, Si-Wu Wu, Bao-Chun Guo
Corrected proof , doi: 10.1007/s10118-021-2626-8
Recently, increasingly growing efforts have been devoted to incorporating dynamic covalent bonds into covalently crosslinked networks to address the persistent trade-offs between chemical crosslinking and malleability. Herein, a series of dynamic aminal bond crosslinked polybutadiene rubbers (PAPB) are prepared by crosslinking aldehyde group-terminated polybutadiene rubber (APB) with piperazine. By varying the molecular weight of APB, the crosslinking density of PAPB is changed, which offers the platform to regulate the mechanical characteristics and dynamic properties. Specially, with the decrease of APB molecular weight, i.e. with the increase of crosslinking density, the modulus of PAPB gradually increases while the elongation at break conversely decreases, and the activation energy for network rearrangement initially decreases and then increases. The resultant PAPB exhibit vitrimer-like behaviors that can alter the network topologies at elevated temperatures without the loss of structural integrity through dissociative aminal exchange reactions, while the protic source can accelerate aminal dissociation and result in network dissolution even at room temperature. Due to the aminal exchange, PAPB are thermally malleable and can almost restore the original mechanical characteristics after recycling; besides, they are capable of healing at a relatively low crosslinking density.
A Unified Thermodynamic Model of Flow-induced Crystallization of Polymer
Cui Nie, Fan Peng, Ting-Yu Xu, Jun-Fang Sheng, Wei Chen, Liang-Bin Li
Corrected proof , doi: 10.1007/s10118-021-2622-z
We propose a unified thermodynamic model of flow-induced crystallization of polymer (uFIC), which incorporates not only the conformational entropy reduction but also the contributions of flow-induced chain orientation, the interaction of ordered segments, and the free energy of crystal nucleus and crystal morphology. Specifically, it clarifies the determining parameters of the critical crystal nucleus size, and is able to account for the acceleration of nucleation, the emergence of precursor, different crystal morphologies and structures induced by flow. Based on the nucleation barrier under flow, we analyze at which condition precursor may occur and how flow affects the competition among different crystal forms such as orthorhombic and hexagonal phases of polyethylene. According to the uFIC model, the different crystal morphologies and structures in the flow-temperature space have been clarified, which give a good agreement with experiments of FIC.
Liquid Crystalline Microdroplets of Graphene Oxide via Microfluidics
Piao Ma, Peng Li, Ya Wang, Dan Chang, Wei-Wei Gao, Chao Gao
Corrected proof , doi: 10.1007/s10118-021-2619-7
Study of stable liquid crystal (LC) microdroplets is of great significance for LC dynamics in confined space or at topological surface. However, the fabrication of LC microdroplets with diverse shape without ionic gelation agents still remains challenging due to the fluid instability. Here, we utilize the microfluidic technology to prepare graphene oxide (GO) LC microdroplets with various morphologies based on the anomalous rheological property of GO aqueous dispersion. Different from LC of one-dimensional polymer, LC containing two-dimensional GO sheets exhibits considerable viscoelasticity and weak extensibility, resulting from the planar molecular conformation and the absence of intermolecular entanglements. The low extensibility ensures that GO aqueous suspension is discretized into monodispersed microdroplets rather than thin thread in the microfluidic channels. The large viscoelasticity and ultra-long relaxation time of GO LC enable the diverse stable morphologies of microdroplets. The droplet morphology is well controlled from sphere to teardrop by modulating the competition between GO viscoelasticity and interfacial tension. The two-dimensional GO LC featuring unique rheological property provides a novel system for the microfluidic field, and corresponding topological stability enriches the LC dynamics and opens a new pathway for designing graphene-based materials.
Intelligent Surfaces Thermally Switchable between the Highly Rough and Entirely Smooth States
Meng Wang, Da Chu, Li Liu, Shuai Huang, Xu-Man Chen, Zhi-Yang Liu, Hong Yang
Corrected proof , doi: 10.1007/s10118-021-2617-9
Reversible switching from a highly rough surface to another entirely smooth surface under external stimuli is crucial for intelligent materials applied in the fields of anti-fogging, self-cleaning, oil-water separation and biotechnology. In this work, a thermal-responsive liquid crystal elastomer (LCE) surface covered with oriented micropillars is prepared via a facile two-step crosslinking method coupled with an extrusion molding program. The reversible change of topological structures of the LCE surface along with temperature is investigated by metallographic microscope, atomic force microscopy and optical contact angle measuring system. At room temperature, the LCE sample is filled with plenty of micropillars with an average length of 8.76 μm, resulting in a super-hydrophobic surface with a water contact angle (WCA) of 135°. When the temperature is increased to above the clearing point, all the micropillars disappear, the LCE surface becomes entirely flat and presents a hydrophilic state with a WCA of 64°. The roughness-related wetting property of this microstructured LCE surface possesses good recyclability in several heating/cooling cycles. This work realizes a truly reversible transformation from a highly rough surface to an entirely smooth surface, and might promote the potential applications of this dynamic-responsive LCE surface in smart sensors and biomimetic control devices.
Visible Light and Temperature Regulated Reflection Colors in Self-supporting Cholesteric Liquid Crystal Physical Gels
Dong-Xu Zhao, Qian Jiang, Jing Wang, Yuan Qiu, Yong-Gui Liao, Xiao-Lin Xie
Corrected proof , doi: 10.1007/s10118-021-2618-8
Photo-responsive cholesteric liquid crystals (CLCs) have attracted much attention in recent years due to their wide applications in filters, tunable optical lasers, dynamic display devices, etc. However, UV light is usually used as the external stimulus source, which is not environment-friendly enough. On the other hand, the mechanical properties of CLCs are not strong enough for these practical applications. Therefore, it still remains a challenge to endow the CLCs with visible light response and high mechanical properties at the same time. Herein, an axially chiral tetra-fluorinated binaphthyl azobenzene gelator ( S-4F-AG ) is synthesized. Upon 550 and 450 nm light irradiations, S-4F-AG exhibits excellent photo-switchable behaviors. Notably, the maximum content of cis-isomer and its half-life are as high as 35% and 89 h in acetonitrile, respectively. A self-supporting CLC physical gel with a storage modulus around 104 Pa can be obtained when 3wt% S-4F-AG and 12wt% binaphthyl azobenzene derivative (dopant 2 ) are co-doped into a nematic LC host P0616A. This CLC physical gel exhibits a temperature-driven blue, green, and red reflection colors reversibly. Importantly, such three primary RGB colors can also be realized by adjusting the exposure time of 550 nm green light. This work lays a solid foundation for the applications ranging from information storage to high-tech anticounterfeit.
Characterization of a Multi-responsive Magnetic Graphene Oxide Nanocomposite Hydrogel and Its Application for DOX Delivery
M. Kurdtabar, S. Saif Heris, M. Dezfulian
Corrected proof , doi: 10.1007/s10118-021-2613-0
Nanocomposite hydrogels are one of the most important types of biomaterials which can be used in many different applications such as drug delivery and tissue engineering. Incorporation of nanoparticles within a hydrogel matrix can provide unique characteristics like remote stimulate and improved mechanical strength. In this study, the synthesis of graphene oxide and graphene oxide nanocomposite hydrogel has been studied. Nanocomposite hydrogel was synthesized using carboxymethyl cellulose as a natural base, acrylic acid as a comonomer, graphene oxide as a filler, ammonium persulfate as an initiator, and iron nanoparticles as a crosslinking agent. The effect of reaction variables such as the iron nanoparticles, graphene oxide, ammonium persulfate, and acrylic acid were examined to achieve a hydrogel with maximum absorbency. Doxorubicin, an anti-cancer chemotherapy drug, was loaded into this hydrogel and its release behaviors were examined in the phosphate buffer solutions with different pH values. The structure of the graphene oxide and the optimized hydrogel were confirmed by Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and atomic force microscopy.
A Robust Self-healing Polyurethane Elastomer Enabled by Tuning the Molecular Mobility and Phase Morphology through Disulfide Bonds
Hai-Tao Wu, Bi-Qiang Jin, Hao Wang, Wen-Qiang Wu, Zhen-Xing Cao, Zhao-Yang Yuan, Yue Huang, Wei-Hang Li, Guang-Su Huang, Lu-Sheng Liao, Jin-Rong Wu
Corrected proof , doi: 10.1007/s10118-021-2607-y
Elastomers with outstanding strength, toughness and healing efficiency are highly promising for many emerging fields. However, it is still a challenge to integrate all these beneficial features in one elastomer. Herein, an asymmetric alicyclic structure adjacent to aromatic disulfide was tactfully introduced into the backbone of polyurethane (PU) elastomer. Specifically, such elastomer (PU-HPS) was fabricated by polycondensing polytetramethylene ether glycol (PTMEG), isophorone diisocyanate (IPDI) and p-hydroxydiphenyl disulfide (HPS) via one-pot method. The molecular mobility and phase morphology of PU-HPS can be tuned by adjusting the HPS content. Consequently, the dynamic exchange of hydrogen and disulfide bonds in the hard segment domains can also be tailored. The optimized sample manifests outstanding tensile strength (46.4 MPa), high toughness (109.1 MJ/m3), high self-healing efficiency after fracture (90.3%), complete scratch recovery (100%) and good puncture resistance. Therefore, this work provides a facile strategy for developing robust self-healing polymers.
Self-healing Polymeric Hydrogels: Toward Multifunctional Soft Smart Materials
Xiao-Ling Zuo, Shao-Fan Wang, Xiao-Xia Le, Wei Lu, Tao Chen
Corrected proof , doi: 10.1007/s10118-021-2612-1
The concept of self-healing that involves a built-in ability to heal in response to damage wherever and whenever it occurs in a material, analogous to the healing process in living organisms, has emerged a couple of decades ago. Driven primarily by the demands for life-like materials and soft smart materials, therefore, the development of self-healing polymeric hydrogels has continually attracted the attention of the scientific community. Here, this review is intended to give an in-depth overview of the state-of-the-art advances in the field of self-healing polymeric hydrogels. Specifically, recently emerging trends in self-healing polymeric hydrogels are summarized, and notably, recommendations to endow these hydrogels with fascinating multi-functionalities including luminescence, conductivity/magnetism and shape memory etc. are presented. To close, the current challenges and future opportunities in this field are also discussed.
A Constitutive Model Describing Molecular Configuration Evolution and Transient Rheological Behavior of Entangled Polymer Solutions
Wen-Jie Yu, Guan-Cheng Shen, Xiao-Wei Zhou, Mao-Yuan Li, Yun Zhang, Hua-Min Zhou, De-Qun Li
Corrected proof , doi: 10.1007/s10118-021-2606-z
Entanglement network is an important structural feature in concentrated polymer solutions and polymer melts, which has a great influence on the transient rheological behavior and molecular configuration evolution. However, the existing constitutive models have limitations in describing the influence of dynamic entanglement behavior on molecular chain motion, resulting in inaccurate descriptions of the transient rheological behavior. Thus, a molecular configuration evolution model for polymer solutions considering the dynamic entanglement effect is proposed by introducing an intermolecular force that changes with the orientation of the molecular chain in this work. The intermolecular force is introduced by considering the friction coefficient as anisotropic, and the orientation effect is considered by introducing an excluded volume dependent anisotropic diffusion. The proposed model can better describe the stress relaxation, stress growth, and dielectric anisotropy of polymer solutions compared with the anisotropy FENE model and FENE model. In addition, the influence of different model parameters on the transient and steady shear response of polymer solution is investigated, and the results show that the influence of volume loss on the friction anisotropy factor kσ increases as the solution concentration increases.
A Fast and Room-temperature Self-healing Thermal Conductive Polymer Composite
De-Wei Yue, Hong-Qin Wang, Han-Qing Tao, Peng Zheng, Cheng-Hui Li, Jing-Lin Zuo
Corrected proof , doi: 10.1007/s10118-021-2620-1
Thermal conducting materials may be damaged during long-term use, resulting in the increase of thermal resistance and therefore inefficient heat dissipation. The introduction of self-healing ability may solve this problem, but the realization of fast and room-temperature self-healing in thermal conducting composites is quite challenging. Herein, we choose a flexible poly(dimethylsiloxane) polymer material ( PDMS-COOH ) as the matrix and graphene nanosheets as the thermal conductive filler to prepare a new kind of thermal conductive polymer composite ( PDMS-COOH-CG ) that can quickly self-heal at room temperature. The thermal conductivity of PDMS-COOH-CG10 with 10% of graphene content is 0.48 W·m−1·K−1, which is 16 times that of PDMS-COOH (0.03 W·m−1·K−1). At room temperature, self-healing efficiency of PDMS-COOH-CG10 based on tensile strength can be 53.8% for 30 s and 84.6% for 24 h. Dynamic infrared thermal imaging dipicted that after 2 min of self-healing at room temperature, the thermal conduction temperature near the damage was basically restored to the level of the pristine sample.
Reactive Core-Shell Bottlebrush Copolymer as Highly Effective Additive for Epoxy Toughening
Junsoo Moon, Yoon Huh, Seonghwan Kim, Youngson Choe, Joona Bang
Corrected proof , doi: 10.1007/s10118-021-2614-z
Herein, we designed a core-shell structured bottlebrush copolymer (BBP), which is composed of rubbery poly(butyl acrylate) (PBA) core and an epoxy miscible/reactive poly(glycidyl methacrylate) (PGMA) shell, as an epoxy toughening agent. The PGMA shell allows BBP to be uniformly dispersed within the epoxy matrix and to react with the epoxy groups, while the rubbery PBA block simultaneously induced nanocavitation effect, leading to improvement of mechanical properties of the epoxy resin. The mechanical properties were measured by the adhesion performance test, and the tensile and fracture test using universal testing machine. When BBP additives were added to the epoxy resin, a significant improvement in the adhesion strength (2-fold increase) and fracture toughness (2-fold increase in KIc and 5-fold increase in GIc) compared to the neat epoxy was observed. In contrast, linear additives exhibited a decrease in adhesion strength and no improvement of fracture toughness over the neat epoxy. Such a difference in mechanical performance was investigated by comparing the morphologies and fracture surfaces of the epoxy resins containing linear and BBP additives, confirming that the nanocavitation effect and void formation play a key role in strengthening the BBP-modified epoxy resins.
The Effect of Trifluoroacetic Acid on Molecular Weight Determination of Polyesters: An in Situ NMR Investigation
Yan-Yan Tu, Xue-Ting Wan, Jie Huan, Xiang Zhu, Xiao-Hong Li, Ying-Feng Tu
Corrected proof , doi: 10.1007/s10118-021-2605-0
Due to the poor solubility of aromatic polyesters in common organic solvents, trifluoroacetic acid is usually used as a co-solvent to increase their solubility for characterizations. However, only few studies have reported the side reactions induced by it. We present here the application of in situ 1H-NMR techniques to explore its effect on the hydroxyl end-groups, which are usually used for the molecular weight determination of polyesters by end-group estimation method. Using bis(2-hydroxyethyl) terephthalate (BHET) as model compound, 1H quantitative NMR results show the peak integration of hydroxyethyl end-groups decreased with time via a pseudo-first-order kinetics in d-trifluoroacetic acid/d-chloroform mixture solvent (1:10, V:V). This is due to the esterification of hydroxyethyl groups with trifluoroacetic acid, revealed by the 1H-13C gradient-enhanced heteronuclear multiple bond correlation (gHMBC) spectrum. The mixtures of dimethyl terephthalate and BHET with different molar ratios were used to represent poly(ethylene terephthalate) (PET) with different degrees of polymerization, and the effect of trifluoroacetic acid on the estimation of hydroxyethyl groups and subsequent molecular weight determination of polyesters was studied. Our results show that if a relative error of 5% is allowed, the NMR measurements must be finished within 1.3 h of solution preparation at 25 °C in the mixture solvent. The results were confirmed in PET sample, while in poly(ethylene adipate), the obtained esterifaction constant is faster that those in aromatic system. The results can be applied to other polymer systems with alcohol functionalized groups, and used as a guideline for the characterization of polyesters and polyethers by end-group estimation method.
Force-Extension Curve of an Entangled Polymer Chain: A Superspace Approach
Huan Gong, Jian-Feng Li, Hong-Dong Zhang, An-Chang Shi
Corrected proof , doi: 10.1007/s10118-021-2623-y
The statistical mechanics of an ideal polymer chain entangled with static topological constraints is studied using a superspace approach, in which the probability distribution of the polymer is obtained as solutions of the Fokker-Planck equation in a superspace with an inner structure characterized by the n-generator free group. The theory predicts that the force-extension curve of the polymer under the topological constraints has the generic form F=kl+Z/l, where l is an effective extension. Aside from the elastic term that is linear in l, the force-extension curve contains a universal term of the form Z/l. The magnitude of this topological term is determined by the topological charge number Z, which characterizes the topological nature of the static constraints. The theoretical results are further verified by a scaling analysis based on a blob model of the chain conformations.
Active Layer Morphology Engineering of All-polymer Solar Cells by Systematically Tuning Molecular Weights of Polymer Donors/Acceptors
Ning Wang, Ying-Jian Yu, Ru-Yan Zhao, Ji-Dong Zhang, Jun Liu, Li-Xiang Wang
Corrected proof , doi: 10.1007/s10118-021-2609-9
In all-polymer solar cells (APSCs), number-average molecular weights (Mns) of polymer donors and polymer acceptors play an important role in active layer morphology and photovoltaic performance. In this work, based on a series of APSCs with power conversion efficiency of approaching 10%, we study the effect of Mns of both polymer donor and polymer acceptor on active layer morphology and photovoltaic performance of APSCs. We select poly[4-(5-(4,8-bis(5-((2-butyloctyl)thio)thiophen-2-yl)-6-methylbenzo[1,2-b:4,5-b']dithiophen-2-yl)thiophen-2-yl)-5,6-difluoro-2-(2-hexyldecyl)-7-(5-methylthiophen-2-yl)-2H-benzo[d][1,2,3]triazole] (CD1) as the polymer donor and poly[4-(5-(5,10-bis(2-dodecylhexadecyl)-4,4,9,9-tetrafluuoro-7-methyl-4,5,9,10-tetrahydro3a,5,8,10-tetraaza-4,9-diborapyren-2-yl)thiophen-2-yl)-7-(5-methylthiophen-2-yl)benzo[c][1,2,5]thiadiazole] (PBN-14) as the polymer acceptor. The Mns of polymer donor CD1 are 14.0, 35.5 and 56.1 kg/mol, respectively, and the Mns of polymer acceptor PBN-14 are 32.7, 72.4 and 103.4 kg/mol, respectively. To get the desired biscontinueous fibrous network morphololgy of the polymer donor/polymer acceptor blends, at least one polymer should have high or medium Mn. Moreover, when the Mn of polymer acceptor is high, the active layer morphology and APSC device performance are insensitive to the Mn of polymer donor. The optimal APSC device performance is obtained when the Mn of both the polymer donor and the polymer acceptor are medium. These results provide a comprehensive and deep understanding on the interplay and the effect of Mn of polymer donors and polymer acceptors in high-performance APSCs.
“Solid-Liquid” Vitrimers Based on Dynamic Boronic Ester Networks
Sheng Wang, Lu-Lu Xue, Xiao-Zhuang Zhou, Jia-Xi Cui
Corrected proof , doi: 10.1007/s10118-021-2592-1
The “solid-liquid” behavior of vitrimers have not been systematically investigated. Herein, a series of “solid-liquid” vitrimers bearing varying contents of dynamic boronic ester bonds were synthesized via thiol-ene click reactions. These vitrimers allow for flexibile modulation of their network structures and thus show a range of intriguing properties including high stretchability, flexible transition from elasticity to plasticity, strong strain rate dependence, and solid-liquid performance. The dynamic association rate of boronic ester bonds within these vitrimers could be apparently accelerated via increasing the content of boronic ester, which could be used to shape-program the flat vitrimer films into various complex 3D structures just with external force. Materials with such versatile dynamic behavior may open up a range of new applications.
Responsive Polymeric Nanoparticles for Biofilm-infection Control
Lin-Zhu Su, Yong Liu, Yuan-Feng Li, Ying-Li An, Lin-Qi Shi
Corrected proof , doi: 10.1007/s10118-021-2610-3
With the emergence of multidrug resistance (MDR) in many pathogens, bacterial infections are becoming a growing threat to public health. The frightening scenario is due largely to the formation of biofilms, in which the bacteria are extremely recalcitrant to the conventional antibiotic regimens. To address the emergence of MDR and biofilm-associated infections, numerous polymer-based materials have been designed and prepared recently. The subject of this perspective is the recent development of polymer-based materials that have been applied to combat multidrug-resistant pathogens, to prevent the formation of biofilms, or enhance the eradication efficacy to mature biofilms via killing biofilm-bacteria or dispersing biofilms. The advantages and shortcomings of these polymer-based materials are discussed, as well as the challenges we are facing in the clinical translation of these systems.
Chiral Recognition and Resolution Based on Helical Polymers
Hui Zou, Qi-Liang Wu, Li Zhou, Xiao-Hua Hou, Na Liu, Zong-Quan Wu
Corrected proof , doi: 10.1007/s10118-021-2615-y
Helical polymers have attracted a great deal of attention and been extensively investigated due to their various applications. One of the most important applications of helical polymers is chiral recognition and resolution of enantiomers for the reason that a pair of enantiomers is commonly with different physiological and toxicological behaviors in biological systems. Helical polymers usually present unexpected high chiral recognition ability to a variety of racemic compounds. What’s more, the chiral recognition and resolution abilities of the system are dependent on the highly ordered helical structures of the helical polymers. This mini review mainly focuses on the recent progress in chiral recognition and resolution based on helical polymers. The synthetic methodology for helical polymers is firstly discussed briefly. Then recent advances of chiral recognition and resolution systems based on helical polymers, especially polyacetylenes and polyisocyanides, are described. We hope this mini review will inspire more interest in developing helical polymers and encourage further advances in chiral-related disciplines.
Aggregate Engineering in Supramolecular Polymers via Extensive Non-covalent Networks
Xin Huang, Dong Lv, Li-Qing Ai, Shuk Han Cheng, Xi Yao
Corrected proof , doi: 10.1007/s10118-021-2608-x
Aggregate engineering of non-covalent networks endows supramolecular polymers with thermo-mechanical versatility, stimuli-responsive phase transitions and intrinsic damage-healing capabilities. However, most non-covalent networks are vulnerable at elevated temperatures, which suppresses the robustness of supramolecular polymers. Herein, ureidocytosine (UCy) motifs, which are capable of forming extensive non-covalent networks and thus robust molecular aggregates via multivalent hydrogen bonds and aromatic stackings, are proposed to enable precise programming of the thermo-mechanical versatility. Molecular simulations reveal that the enthalpic contributions from the UCy aggregates play dominant roles to compensate the entropic loss from the redistributions of polymeric spacers and stabilize the non-covalent networks over wide temperature windows. Such aggregate-level strategy offers prospects for applications which require thermo-mechanical versatility of supramolecular polymers, such as 3D printing, microfabrication and damage-healing coating.
Nonlinear Viscoelasticity Raised at Low Temperatures by Intermolecular Cooperation of Bulk Amorphous Polymers
Ji-Ping Wang, Wen-Bing Hu
Corrected proof , doi: 10.1007/s10118-021-2624-x
We performed dynamic Monte Carlo simulations of stress relaxation in parallel-aligned and uniaxially stretched bulk amorphous polymers at low temperatures. We observed an extra-slowing down in the early stage of stress relaxation, which causes nonlinear viscoelasticity as deviated from Debye relaxation and Arrhenius-fluid behaviors observed previously at high temperatures. Meanwhile, fluctuation analysis of stress relaxation revealed a substantial increase in the stretch fractions of polymers at the transient periods of high-temperature Debye relaxation. Structural analysis of free volume further revealed the scenario that, at low temperatures, the modulus of polymer entropy elasticity decreases with temperature and eventually loses its competition to the imposed modulus (Deborah number becomes larger than one), and hence upon stress relaxation under constant strains, monomers are firstly accumulated nearby two stretching ends of polymers, resulting in tentative global jamming like physical cross-linking there, and thus retarding the coming transient state of stress relaxation. We concluded that intermolecular cooperation raises physical crosslinking for nonlinear viscoelasticity of polymer stress relaxation as well as the rubbery states unique to bulk amorphous polymers. The new microscopic mechanism of the fluid-rubbery transition of polymers may bring insights into the intermolecular cooperation mechanism of glass transition of small molecules, if the fluid-rubbery transition is regarded as an extrapolation of glass transition from low to high molecular weights.
Polymerizable AEE-active Dye with Optical Activity for Fluorescent Nanoparticles Based on Phenothiazine: Synthesis, Self-assembly and Biological Imaging
Zeng-Fang Huang, Ya-Li Chen, Chao-Yue Zhou, Yan-Hong Li, Mei Li, Xiao-Bo Liu, Liu-Cheng Mao, Jin-Ying Yuan, Lei Tao, Yen Wei
Corrected proof , doi: 10.1007/s10118-021-2596-x
In consideration of various advantages such as less harm, higher sensitivity, and deeper imaging depth, etc., AIE materials with long-wave emission are attracting extensive attention in the fields of vascular visualization, organelle imaging, cells tracker, forensic detection, bioprobe and chemosensor, etc. In this work, a novel fluorescent (R)-PVHMA monomer with chirality and aggregation-induced emission enhancement (AEE) characteristics was acquired through enzymatic transesterification reaction basing on phenothiazine, and its \begin{document}${\left[\alpha \right]}_{D}^{25^\circ {\rm{C}}}$\end{document} value was about −6.39° with a 3.08 eV bandgap calculated by the quantum calculations. Afterwards, a series of PEG-PVH1 and PEG-PVH2 copolymers with chirality feature were achieved through RAFT polymerization of the obtained (R)-PVHMA and PEGMA with various feed ratios. When the feed molar ratio of (R)-PVHMA increased from 21.5% to 29.6%, its actual molar fractions in the PEG-PVH1 and PEG-PVH2 copolymers accordingly increased from 18.1% to 25.7%. The molecular weight of PEG-PVH1 was about 2.2×104 with a narrow PDI, and their kinetics estimation showed a first-order quasilinear procedure. In aqueous solution, the amphiphilic copolymers PEG-PVH could self-assemble into about 100 nm nano-particles. In a 90% water solution of H2O and THF mixture, the fluorescence intensity had the maximum value, and the emission wavelength presented at 580 and 630 nm. The investigation of cytotoxicity and cells uptake showed that PEG-PVH FONs performed outstanding biocompatibility and excellent cells absorption effects, which have great potential in bioimaging application.
Tunable Multiple Morphological Transformation of Supramolecular Hyperbranched Polymers Based on an A2B6-type POSS Monomer
Lin-Feng Fan, Cui-Ling Hou, Xing Wang, Li-Tang Yan, De-Cheng Wu
Corrected proof , doi: 10.1007/s10118-021-2598-8
The growing demands of supramolecular hyperbranched polymers integrating noncovalent interaction and unique topological structure merits had received considerable interest in the fabrication of novel materials for advanced applications. Herein, we prepared A2B6-type POSS-containing supramolecular hyperbranched polymers with multiple morphologies including lamellar-like, branched, hollow, core-shell and porous spherical structures through regulating self-assembling monomer concentrations and solvent polarities. The incorporation of appropriate emulative guest molecules would further trigger morphological transformations (such as vesicles and spherical micelles) by synergistic effects of unique POSS aggregation ability, supramolecular complexations and hydrophilic-hydrophobic interactions. Thus, this facile and universal strategy may enable a modular nanofabrication of supramolecular hyperbranched polymers with diversiform topological structure and sophisticated multifunctionality for their potential applications.
Kinetic Pattern Formation with Intermolecular Interactions: A Modified Brusselator Model
Rui-Qi Sun, Jian-Feng Li, Hong-Dong Zhang, Yu-Liang Yang
Corrected proof , doi: 10.1007/s10118-021-2600-5
In this work, we modify the traditional Brusselator model to incorporate the intermolecular interactions, based on which a systematic study is performed on the pattern formation mediated by chemical reaction and phase separation. It is found that if the chemical reaction dominates, the pattern formation will be inhibited by the phase separation while if the phase separation dominates, the chemical reaction will prevent, under certain conditions, the domain size from growing which results in dissipative patterns other than macroscopic phase separations.
Tuning the Johari-Goldstein β-Relaxation and Its Separation from α-Relaxation of Poly(n-alkyl methacrylate)s by Small Molecule-bridged Hydrogen Bonds
Yuan-Biao Liu, Gao-Peng Shi, Guo-Zhang Wu
Corrected proof , doi: 10.1007/s10118-021-2595-y
Introducing small molecule-bridged hydrogen bonds (HBs) between polymer chains has been reported to effectively reduce the inter-chain cooperativity despite of strengthening the intermolecular interaction. Here, a systematic investigation on tuning the Johari-Goldstein β (βJG) relaxation by adding various low-molecular-weight phenols in poly(n-alkyl methacrylate)s is carried out to further clarify the anomalous dynamics. Given these small molecules capable of coupling the motion with pendent groups of host polymers due to forming at least two HBs per molecule, poly(n-alkyl methacrylate) mixtures exhibit rich dynamic changes in the βJG-properties and α, βJG separations. An increased loading of phenols with a small size and strong inter-HB strength (Δυi) clearly benefits for significant retardation and suppression of the βJG-relaxation, narrows the α, βJG separation and converges the βJG-peak with the α-peak, which demonstrates the alleviation of inter-chain topological constraints. However, small molecules with a relatively big size and weak Δυi are found to amplify the magnitude of the α, βJG separation of poly(butyl methacrylate), even though experimental results of changes in α-dispersion and dynamic fragility confirm a reduction of the coupling factor n in all of these hybrids. The counterintuitive phenomenon suggests that the crossover time tc in the Coupling Model is no longer a universal quantity if the inter-chain interaction of polymers is strengthened by HBs. These compelling findings shed vital insights into the HB-induced anomalous dynamics, and provide essential guidance for tailoring the βJG behavior and designing glassy polymeric materials.
Carbon Dots Intensified Mechanochemiluminescence from Waterborne Polyurethanes as Tunable Force Sensing Materials
Bo-Han Cao, Wu Chen, Wan-Yuan Wei, Yu-Lan Chen, Yuan Yuan
Corrected proof , doi: 10.1007/s10118-021-2601-4
1,2-Dioxetane is a well-known chemiluminescent mechanophore allowing real-time monitoring of polymer chain scission, but usually suffers from fluorescence quenching in polar environments. Herein, a series of mechanochemiluminescent waterborne polyurethanes/carbon dots composites ( WPU-CDs ) have been synthesized by incorporating fluorescent CD s to promote the energy transfer process in different environments. The resulting bulk WPU s, and in particular, their swollen films filled with a large amount of polar solvents (water and ionic liquid) emit intense mechanochemiluminescence. Thus force-induced covalent bond scission and stress distribution within these different WPU-CDs films can be sensitively visualized. Furthermore, the ionic liquid containing films exhibited both electrical and luminescent signal changes under stretching, which offer a new kind of force sensor responsive at a broad detecting strain range and for multi-mode strain analysis. This study is expected to stimulate new research endeavors in mechanistic insight on waterborne polyurethanes and the corresponding stretchable sensing devices.
Monoclonal Antibody-conjugated Polyphosphoester-hyd-DOX Prodrug Nanoparticles for Targeted Chemotherapy of Liver Cancer Cells
Ya-Kui Huang, Hong-Rui Tian, Ming-Zu Zhang, Jin-Lin He, Jian Liu, Pei-Hong Ni
Corrected proof , doi: 10.1007/s10118-021-2582-3
In order to overcome the limitation of traditional active nano-therapeutic drugs on tumor targeting efficiency which cannot reach the receptor/target in sufficient amount in the body, in this work, we developed a monoclonal antibody (mAb) and a polymer-hyd-doxorubicin prodrug conjugate, which enables the self-assembled nanoparticles to have precise targeting, tumor tissue aggregation and pH-sensitive drug release. We first prepared an amphiphilic polymer prodrug, abbreviated as H2N-PEEP-b-PBYP-hyd-DOX, via a combination of ring-opening polymerization (ROP) and “click” chemistry, in which PEEP and PBYP represent two kinds of phosphoester segmemts, -hyd- is hydrazone bond. After self-assembly into prodrug nanoparticles (PDNPs) with a diameter of about 93 nm, CD147 mAb was conjugated onto the PDNPs by EDC/NHS chemistry to form mAb-PDNPs. For the PDNPs and mAb-PDNPs, we also investigated their stability, in vitro drug release behavior and cellular uptake. The results showed that the pH-responsive PDNPs can remain relatively stable under the condition of PB 7.4 buffer solution. However, under acidic conditions or in the presence of phosphodiesterase I (PDE I), both the amount and rate of DOX release increased at the same incubation period. Cytotoxicity assay showed that mAb-PDNPs exhibited higher cytotoxicity (IC50: 1.12 mg·L−1) against HepG2 cells than PDNPs (IC50: 2.62 mg·L−1) without monoclonal antibody. The nanoparticles with antibodies mAb-PDNPs have relatively better stability and can directly achieve the targeting drug delivery through CD147 mAb.
A Unified Theoretical Treatment on Statistical Properties of the Semi-batch Self-condensing Vinyl Polymerization System
Fang Gu, Jiang-Tao Li, Xiao-Zhong Hong, Hai-Jun Wang
Corrected proof , doi: 10.1007/s10118-021-2603-2
We present a novel generating function (GF) method for the self-condensing vinyl polymerization (SCVP) system with any initial distribution of preexisted polymers. Such a method was proven to be especially useful to investigate the semi-batch SCVP system allowing a sequence of feeding operations during the polymerization. Consequently, the number-, weight-, and z-average molecular weights as well as dispersity index of hyperbranched polymers can be explicitly given, which are determined by predetermined feeding details and conversions in each polymerization step. These analytical results are further confirmed by the corresponding Monte Carlo simulations. Therefore, the present GF method has provided a unified treatment to the semi-batch SCVP system. Accordingly, hyperbranched polymers with desired properties can be prepared by designing feeding details and presetting conversions at each step based on the present GF method.
Simultaneous Enhancement of Toughness and Strength of Stretched iPP Film via Tiny Amount of β-Nucleating Agent under “Shear-free” Melt-extrusion
Zhong-Zhu Liu, Guo-Qiang Zheng, Hong-Hui Shi, Chun-Tai Liu, Li-Wei Mi, Qian Li, Xian-Hu Liu
Corrected proof , doi: 10.1007/s10118-021-2589-9
Herein, isotactic polypropylene films with small β-nucleating agent content were fabricated via a melt-extrusion-stretched technology with intended “shear-free” in barrel and die. Compared with neat films, the tensile strength, elongation at break and strain energy density at break of iPP film with 0.05 wt% β-nucleating agent are significantly improved by 13.8%, 39.6% and 90.6%, respectively, indicating the simultaneously enhanced toughness and strength. Additionally, the β-crystal content gradually increases with increasing β-NA content, while the relative total daughter content of α- and β-crystal exhibits opposite tendency. Moreover, nucleation and crystal growth induced by various β-NA contents are different. This work proves an efficient strategy to enhance mechanical properties of isotactic polypropylene film via controlling elongation flow and addition of appropriate β-NA content.
Supramolecular Self-assembly Behaviors of Asymmetric Diblock Copolymer Blends with Hydrogen Bonding Interactions between Shorter Blocks Modelled by Yukawa Potentials
Xu Zhang, Jialiang Chen, Lin Xu, Tianxi Liu
Corrected proof , doi: 10.1007/s10118-021-2591-2
We employed the extended self-consistent field theory to investigate the supramolecular self-assembly behaviors of asymmetric diblock copolymer blends (AB/B’C) with hydrogen bonding interactions between shorter B and B’ blocks. The hydrogen bonding interactions are described by Yukawa potentials, where the hydrogen bonding donors and acceptors were modelled as two blocks smeared with opposite screened charges. The hierarchical microstructures with parallelly packed lamellae-in-lamellae ( Lam ) and 4.8.8 Archimedean tilting pattern ( 4.8.8 ) were observed at lower and higher hydrogen bonding density (θ), respectively. The hierarchy of Lam and 4.8.8 were demonstrated by the one- and two-dimensional density profiles and the underlying order of the large-length-scale and small-length-scale microstructures were also clarified. It was found that the 4.8.8 is favorable to the stronger hydrogen bonding density or interactions. As θ increases, the microphase transition from Lam to 4.8.8 occurs at θ=0.34, which is mainly attributed to the optimization of the electrostatic energy and conformational entropy with sacrificing the interfacial energy. This work can provide a new strategy to understand the supramolecular self-assembly as well as the mechanism behind the formation of complex hierarchical microstructures.
Denting Nanospheres with a Short Peptide
Sha Lin, Hui Sun, Erik Jan Cornel, Jin-Hui Jiang, Yun-Qing Zhu, Zhen Fan, Jian-Zhong Du
Corrected proof , doi: 10.1007/s10118-021-2599-7
Dented nanospheres show promising potential in drug delivery, nanomotors, etc. However, it is still challenging to prepare them by homopolymer self-assembly because of the strict structural requirements of the homopolymer. Herein, we propose a strategy for preparing dented nanospheres from homopolymers by co-assembly with a short peptide. They were co-assembled from poly(2-hydroxy-3-((4-(ethoxycarbonyl)phenyl)amino)propyl methacrylate) (PHBzoMA59) and (S)-2-((S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-phenylpropanamido)-3-phenylpropanoic acid (Fmoc-FF-OH). PHBzoMA homopolymers can only self-assemble into nanospheres without dent, and the addition of a short peptide introduced hydrogen bonding and complementary π-π stacking interactions led to the final dented nanosphere morphology. The weight fractions of the short peptide can be adjusted to regulate the final morphology. It was confirmed that the radius of curvature of the dent on the surface was related to the organic bubble inside the protospheres prepared at critical aggregation concentration (CAC). The organic bubble can be adjusted by altering the kind of organic solvent and solution pH, which allowed control over the dented nanosphere dimension. The use of different organic solvents with various polarities allows adjustment of the interfacial tension, and hence the denting degree. This degree can also be controlled by manipulating the solution pH to (de)protonate the short peptide and homopolymer. Furthermore, the versatility of this method was highlighted by using a different homopolymer and the applicability of the resulting dented nanospheres was demonstrated by decoration with gold nanoparticles. Overall, this study provided important insights and a new simple strategy to prepare dented nanospheres in a controlled fashion.
Thermal, Rheological and Mechanical Properties of Biodegradable Poly(propylene carbonate)/Epoxidized Soybean Oil Blends
Ling Zhao, Shi-Ling Jia, Ze-Peng Wang, Yun-Jing Chen, Jun-Jia Bian, Li-Jing Han, Hui-Liang Zhang, Li-Song Dong
Corrected proof , doi: 10.1007/s10118-021-2590-3
Biodegradable poly(propylene carbonate) (PPC)/epoxidized soybean oil (ESO) blends with different component ratios were prepared by melt blending to improve the performance of PPC. The phase morphology, thermal properties, rheological properties and mechanical properties of the blends were investigated in detail. SEM examination revealed good interfacial adhesion between PPC matrix and ESO. According to DSC and DMA, as the content of ESO increased, the glass transition temperature of the PPC component increased, indicating that there was a strong interfacial interaction between the PPC matrix and ESO. The interfacial interaction may be caused by ring-opening reaction between the hydroxyl end groups of PPC and the epoxy groups of ESO, which restricted the chain movement of PPC matrix. The disappearance of the epoxy groups in FTIR indicated that the interfacial interaction between the two phases was due to the ring-opening reaction between PPC and ESO. With the addition of ESO, the thermal stabilities were enhanced. With the increasing ESO content, the modulus gradually decreased. However, the strength at yield, the strength at break and the elongation at break were increased for the PPC/ESO blends, suggesting that the enhancement of the strength and toughness of PPC was achieved by the incorporation of ESO. The rheological measurement revealed that the complex viscosity, storage modulus and loss modulus of PPC were increased with the increasing ESO content at low frequency, which indicated that the addition of ESO enhanced the melt strength of PPC instead of plasticizing PPC.
Biodegradable Polypeptide-based Vesicles with Intrinsic Blue Fluorescence for Antibacterial Visualization
Yu-Ying Yang, Ling-Shan Chen, Min Sun, Cong-Yu Wang, Zhen Fan, Jian-Zhong Du
Corrected proof , doi: 10.1007/s10118-021-2593-0
Fluorescence imaging has been an indispensable tool to provide dynamic information about the localization and quantity of organisms. Meanwhile, due to the intrinsic hollow structure and modularized biofunctionalities, polymer vesicles have been widely applied in biomedical field. However, most polymer vesicles are embedded with organic fluorophores for fluorescence imaging, which have certain drawbacks such as leakage and possible cytotoxicity. Here, we present a biodegradable polypeptide-based vesicle with intrinsic blue fluorescence without introducing any fluorophore for real-time visualization of antibacterial process. Through modular design to integrate multiple functional fragments, poly(ε-caprolactone)-block-poly(tryptophan)-block-poly(lysine-stat-phenylalanine) [PCL25-b-PTrp2-b-P(Lys13-stat-Phe4)] was synthesized, where PCL chains form the hydrophobic membrane, P(Lys-stat-Phe) and PTrp provide intrinsic fluorescence and broad-spectrum antibacterial activity. It is noteworthy that the fluorescence emission was shifted from invisible ultraviolet range of amino acids to visible range (emission maximum at 436 nm), which makes it possible to visualize the antibacterial process. In addition, through utilizing the intrinsic fluorescence of vesicles, confocal fluorescent imaging of vesicles with bacteria validated the specific adhesion of vesicle towards bacteria, and the bacterial death through membrane disruption. Overall, we provided a novel approach to developing biodegradable fluorescent polypeptide-based vesicles for real-time visualization of antibacterial process.
Mixing of Racemic Poly(L-lactide)/Poly(D-lactide) Blend with Miscible Poly(D,L-lactide): Toward All Stereocomplex-type Polylactide with Strikingly Enhanced SC Crystallizability
Yi-Long Ju, Xiang-Li Li, Xing-Yuan Diao, Hong-Wei Bai, Qin Zhang, Qiang Fu
Corrected proof , doi: 10.1007/s10118-021-2588-x
Stereocomplex-type polylactide (SC-PLA) consisting of alternatively arranged poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) chains has gained a good reputation as a sustainable engineering plastic with outstanding heat resistance and durability, however its practical applications have been considerably hindered by the weak SC crystallizability. Current methods used to enhance the SC crystallizability are generally achieved at the expense of the precious bio-renewability and/or bio-degradability of PLAs. Herein, we demonstrate a feasible method to address these challenges by incorporating small amounts of poly(D,L-lactide) (PDLLA) into linear high-molecular-weight PLLA/PDLA blends. The results show that the incorporation of the atactic PDLLA leads to a significant enhancement in the SC crystallizability because its good miscibility with the isotactic PLAs makes it possible to greatly improve the chain mixing between PLLA and PDLA as an effective compatibilizer. Meanwhile, the melt stability (i.e., the stability of PLLA/PDLA chain assemblies upon melting) could also be improved substantially. Very intriguingly, SC crystallites are predominantly formed with increasing content and molecular weight of PDLLA. More notably, exclusive SC crystallization can be obtained in the racemic blends with 20 wt% PDLLA having weight-average molecular weight of above 1×105 g/mol, where the chain mixing level and intermolecular interactions between the PLA enantiomers could be strikingly enhanced. Overall, our work could not only open a promising horizon for the development of all SC-PLA-based engineering plastic with exceptional SC crystallizability but also give a fundamental insight into the crucial role of PDLLA in improving the SC crystallizability of PLLA/PDLA blends.
Bending-stability Interfacial Layer as Dual Electron Transport Layer for Flexible Organic Photovoltaics
Guodong Xu, Xiaotian Hu, Xunfan Liao, Yiwang Chen
Corrected proof , doi: 10.1007/s10118-021-2586-z
The flexibility of organic photovoltaics (OPVs) has attracted worldwide attention in recent years. To realize the bending-stability of OPVs, it is necessary to put forward the bending-stability of interfacial layer. A novel bendable composite is explored and successfully applied as an electron transport layer (ETL) for fully-flexible OPVs. We incorporated poly(vinylpyrrolidone)(PVP) into conjugated electrolytes (CPE) to composite a bendable ETL for high-performance OPVs devices. Fortunately, the devices based on PVP-modified CPE exhibited better device performances and more excellent mechanical properties of bendability. The fullerene-free OPVs based on PM6:IT-4F with CPE@PVP as ETLs yield the best power conversion efficiency (PCE) of 13.42%. Moreover, a satisfying efficiency of 12.59% has been obtained for the fully-flexible OPVs. As far as we know, this is one of the highest PCE for fully-flexible OPV based PM6:IT-4F system. More importantly, the flexible OPVs devices can retain more than 80% of its initial efficiency after 5000 bending cycles. Furthermore, among various curvature radii, the mechanical properties of the device based on CPE@PVP are superior to those of the device based on bare CPE as ETL. These findings indicate that the functional flexibility of CPE as a cathode interfacial layer is an effective strategy to fabricate high-performance flexible devices in the near future.
Construction of Chiroptical Switch on Silica Nanoparticle Surface via Chiral Self-assembly of Side-chain Azobenzene-containing Polymer
Guang-Xing Song, Teng-Fei Miao, Xiao-Xiao Cheng, Hao-Tian Ma, Zi-Xiang He, Wei Zhang, Zheng-Biao Zhang, Xiu-Lin Zhu
Corrected proof , doi: 10.1007/s10118-021-2580-5
In this contribution, we utilized surface-initiated atom transfer radical polymerization (SI-ATRP) to prepare organic-inorganic hybrid core/shell silica nanoparticles (NPs), where silica particles acted as cores and polymeric shells (PAzoMA*) were attached to silica particles via covalent bond. Subsequently, chiroptical switch was successfully constructed on silica NPs surface taking advantage of supramolecular chiral self-assembly of the grafted side-chain Azo-containing polymer (PAzoMA*). We found that the supramolecular chirality was highly dependent on the molecular weight of grafted PAzoMA*. Meanwhile, the supramolecular chirality could be regulated using 365 nm UV light irradiation and heating-cooling treatment, and a reversible supramolecular chiroptical switch could be repeated for over five cycles on silica NPs surface. Moreover, when heated above the glass transition temperature (Tg) of PAzoMA*, the organic-inorganic hybrid nanoparticles (SiO2@PAzoMA* NPs) still exhibited intense DRCD signals. Interestingly, the supramolecular chirality could be retained in solid film for more than 3 months. To conclude, we have prepared an organic-inorganic hybrid core/shell chiral silica nanomaterial with dynamic reversible chirality, thermal stability and chiral storage functions, providing potential applications in dynamic asymmetric catalysis, chiral separation and so on.
Construction of Supramolecular Chirality in Polymer Systems: Chiral Induction, Transfer and Application
Xiao-Xiao Cheng, Teng-Fei Miao, Lu Yin, Wei Zhang, Xiu-Lin Zhu
Corrected proof , doi: 10.1007/s10118-021-2561-8
Chirality, commonly found in organisms, biomolecules and nature such as L-amino acids and D-sugars, has been extensively studied in chemistry and biomedical science. Hence, the demand for simple and efficient construction of chiral structures, especially chiral polymers, has been rapidly growing due to their potential applications in chemosensors, asymmetric catalysis and biological materials. However, most chiral polymers reported are prepared directly from chiral monomers/chiral catalysts, the corresponding strategies usually involve tedious and expensive design and synthesis. Fortunately, chirality induction strategies (such as circularly polarized light, chiral solvation and chiral gelation etc.) have been known to be highly versatile and efficient in producing chirality from achiral polymers. In this feature article, the current research on chirality induction, transfer and application in achiral polymer systems is summarized. Furthermore, this article discusses some basic concepts, seminal studies, recent advances, the structural design principles, as well as perspectives in the construction and applications of chiral polymers derived from achiral monomers, with the hope to attract more interest from researchers and further advance the development of chiral chemistry.
Dendrimer-based Hydrogels with Controlled Drug Delivery Property for Tissue Adhesion
Ya-Qiang Wang, Xue-Yu Dou, Hu-Fei Wang, Xing Wang, De-Cheng Wu
Corrected proof , doi: 10.1007/s10118-021-2584-1
In recent years, the hydrogel-based tissue adhesives have been extensively investigated for their excellent biocompatibility and the ability to be administered directly within the adherent tissue. To meet the requirement for more controllable release in various physiological settings, the components of hydrogel adhesive should be more precisely tailored. In this work, the POSS-ace-PEG hydrogel adhesive was fabricated with the polyacetal dendrimer G1'-[NH3Cl]16 and poly(ethylene glycol) succinimidyl carbonate (PEG-SC) due to the regular peripheral amino structure of G1'-[NH3Cl]16. Rheological and adhesion tests demonstrated that the hydrogel adhesive had good mechanical and adhesive properties, which could effectively adhere to the pigskin and severed nerves. Moreover, the tissue adhesive exhibited good stability under neutral conditions and the rapid degradation under acidic conditions, allowing for the release of doxycycline hydrochloride (DOX) drug in response to pH. Together, these results suggested that the POSS-ace-PEG adhesive had the potential to provide an alternative to tissue adhesives for applications in pathological environments (inflammation, tumors, etc.).
Photoinduced Reversible Solid-to-Liquid Transitions and Directional Photofluidization of Azobenzene-containing Polymers
Shuo-Feng Liang, Chen Nie, Jie Yan, Qi-Jin Zhang, Si Wu
Corrected proof , doi: 10.1007/s10118-021-2519-x
Photoinduced reversible liquefaction and solidification of polymers enable processing and healing of polymers with light. Some azobenzene-containing polymers (azopolymers) exhibit two types of photoinduced liquefaction properties: photoinduced reversible solid-to-liquid transition and directional photofluidization. For the first type, light switches the glass transition temperature (Tg) values of azopolymers and induces reversible solid-to-liquid transitions. For the second type, polarized light guides solid azopolymers to flow along the polarization direction. Here, we compare the two types of photoliquefaction and discuss their mechanisms. Recent progresses and applications based on photoliquefaction of azopolymers are also highlighted.
Payne Effect and Weak Overshoot in Rubber Nanocomposites
Zhiyun Li, Yihu Song, Qiang Zheng
Accepted Manuscript , doi: 10.1007/s10118-021-2643-7
Payne effect and its associated weak overshoot are of importance for understanding and regulating the softening of rubber nanocomposites under large amplitude oscillations. Herein Payne effect in diverse filled vulcanizates is investigated for generalizing the common characteristics. Master curves of strain amplitude dependent storage modulus are created with respect to microscopic strain amplitude of the matrix, revealing a matrix-dominated elastic nonlinearity being independent of type and dispersity of filler, crosslinking density and sol fraction of matrix and filler-rubber interfacial interactions. However, carbonaceous fillers with higher affinity to the rubber matrices yield lower strain amplification and higher overshoot behavior in comparison with siliceous silica. The investigation would be illuminating for preparing rubber nanocomposites with optimized reinforcement and softening performances.
Software package: an advanced theoretical tool for inhomogeneous fluids (Atif)
Jian Jiang
Accepted Manuscript , doi: 10.1007/s10118-021-2646-4
In spite of the impending flattening of Moore’s law, the complexity and size of the systems we are interested in keep on increasing. This challenges the computer simula tion tools due to the expensive computational cost. Fortunately, advanced theoretical methods can be considered as alternatives to accurately and efficiently capture the structural and thermodynamic properties of complex inhomogeneous fluids. In the last decades, classical density functional theory (cDFT) has proven to be a sophisticated, robust, and efficient approach for studying complex inhomogeneous fluids. In this work, we present a pedagogical introduction to a broadly accessible open-source density functional theory software package named “an advanced theoretical tool for inhomogeneous fluids” (Atif) and of the underlying theory. To demonstrate Atif, we take three cases as examples using a typical laptop computer: (i) electric double-layer of asymmet ric electrolytes; (ii) adsorptions of sequence-defined semiflexible polyelectrolytes on an oppositely charged surface; and (iii) interactions between surfaces mediated by polyelec16 trolytes. We believe that this pedagogical introduction will lower the barrier to entry to the use of Atif by experimental as well as theoretical groups. A companion website, which provides all of the relevant sources including codes and examples, is attached.
Polymer Vesicles with Upper Critical Solution Temperature for Near-Infrared Light-Triggered Transdermal Delivery of Metformin in Diabetic Rats
Wei Hu, Yawei Su, Yikun Jiang, Wendi Fan, Songyue Cheng, Zaizai Tong, Chao Cen, Guohua Jiang
Accepted Manuscript , doi: 10.1007/s10118-021-2640-x
Near-infrared light (NIR) triggered transdermal drug delivery systems are of great interest due to their on-demand drug release, which enable to enhance drug treatment efficiency as well as reduce side effect. Herein, a NIR-triggered microneedle (MN) patch array has been fabricated through depositing the photothermal conversion agent and anti-diabetic drug-loaded polymer vesicles with upper critical solution temperature (UCST) into dissolvable polymer matrix. The UCST-type polymer has a clearing point temperature of 41 °C and the drug-loaded polymer vesicles present excellent NIR-triggered and temperature responsive drug release behavior in vitro due to the disassociation of polymer vesicles upon NIR irradiation. After applying MNs to diabetic rats, significant hypoglycemic effect is achieved upon interval NIR irradiation and the blood glucose concentration can decrease to normal state for several hours, which enables to achieve the goal of on-demand drug release. This work suggests the NIR-triggered MN drug release device has a potential application in the treatment of diabetes, especially for those require an active drug release manner.
High Performance Electrospun Polynaphthalimide Nanofibrous Membranes with Excellent Resistance to Chemically Harsh Conditions
Mengjie Yuan, Zhaoyu Hu, Hong Fang, Shujing Li, Hongtao Guo, Rubei Hu, Shaohua Jiang, Kunming Liu, Haoqing Hou
Accepted Manuscript , doi: 10.1007/s10118-021-2634-8
Polynaphthalimide (PNI) with six-membered imide ring (6-PI) has better chemical resistance than five-membered imide ring (5-PI), but is difficult to be processed into nanofibers due the poor processability. In this work, we proposed a template strategy to fabricate nanofiber 6-PI membranes and their composite membranes. Pure 6-PI and 6-PI composite fibrous membranes were prepared using high-molecular-weight polymers 5-PAA and PVP as templates by electrospinning. FT-IR, DMA, TGA and tensile tests were used to characterize their chemical structures, thermal stability and mechanical properties. Further eye-observation, micro-morphology investigation and tensile tests were applied to evaluate the chemical resistance of nanofibrous membranes in strong acid, strong alkaline, and concentrated salt. The results demonstrated that 6-PI nanofibrous membranes possessed the best thermal stability, best acid, alkaline, and salt resistance with the highest mechanical retention. This research will provide basic information for high-performance electrospun 6-PI nanofiber membranes and provide opportunities for applications of PIs in different chemically harsh environments.
Phenylethynyl-Terminated Imide Oligomers Modified by Reactive Diluent for Resin Transfer Molding Application
Weijie Hong, Lili Yuan, Haoyang Zhang, Chao Cui, Wei Chen, Shiyong Yang
Accepted Manuscript , doi: 10.1007/s10118-021-2636-6
To meet the processing requirements of resin transfer moulding (RTM) technology, reactive diluent containing m-phenylene moiety was synthesized to physically mixed with phenylethynyl terminated cooligoimides with well-designed molecular weights of 1500 - 2500 g/meal derived from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3,4'-Oxydianiline (3,4'-ODA) and m-phenylenediamine (m-PDA). This blend shows low minimum melting viscosity (< 1 Pa·s) and enlarged processing temperature window (260 – 361 Oz). FPI-R-1 stays below 1 Pa·s for 2 h at 270 OC. The relationship between the molecular weight of the blend and its melting stability was first explored. Blending oligoimides with lower molecular weights exhibits better melting stability. Upon curing at the 380 OC for 2 h, the thermosetting Polyimide resin demonstrates superior heat resistance (Tg = 420 - 426 Oz).
CO2-based Biodegradable Supramolecular Polymers with Well-tunable Adhesive Properties
Xiaojing Li, Yingfeng Wen, Yong Wang, Haiyan Peng, Xingping Zhou, and Xiaolin Xie
Accepted Manuscript , doi: 10.1007/s10118-021-2641-9
Supramolecular adhesives that enable debonding on-demand are of significant research interest for the development of adaptive and smart materials, yet, biodegrable supramolecular adhesives have been rarely exploited. Herein, telechelic, three-armed and four-armed CO2-based polyols with close molecular weights and various CO2 content (or carbonate unite content) have been synthesized via a zinc-cobalt double metal cyanide complex catalyzed ring-opening copolymerization of CO2 and propylene oxide, and further exploited as sustainable and biodegradable building blocks for supramolecular polymers (SMPs) with 2-ureido-4[1H]-pyrimidinone (UPy) motifs. Notably, the orthogonal modulation of the CO2 content and the topology of CO2-based polyols provides a unique opportunity to fine-tune the surface energy as well as the cohesive strength of the resulting CO2-based SMPs. Notably, a three-armed SMP with a CO2 content of 44% (3UPy-CO2-44%) can well balance the trade-off between surface energy and cohesive strength, therefore bestowing a high adhesive strength of 7.5 MPa and 9.7 MPa by testing single lap joints with stainless steel and wood substrates, respectively. Moreover, the light-responsive adhesion property of 3UPy-CO2-44% has been demonstrated exemplarily by blending with a UV sensitizer.
Hydrogels with dynamically controllable mechanics and biochemistry for 3D cell culture platforms
Haiyang Wu, Lei Yang, Jiangshan Tu, Jie Wang, Jinge Li, Hongying Lv, and Xiaoniu Yang
Accepted Manuscript , doi: 10.1007/s10118-021-2639-3
Many cell-matrix interaction studies have proved that dynamic changes in the extracellular matrix (ECM) are crucial to maintain cellular properties and behaviors. Thus, developing materials that can recapitulate the dynamic attributes of the ECM is highly desired for three-dimensional (3D) cell culture platforms. To this end, we sought to develop a hydrogel system that would enable dynamic and reversible turning of its mechanical and biochemical properties, thus facilitating the control of cell culture to imitate the natural ECM. Herein, a hydrogel with dynamic mechanics and a biochemistry based on an addition-fragmentation chain transfer (AFCT) reaction was constructed. Thiol-modified hyaluronic acid (HA) and allyl sulfide-modified ε-poly-L-lysine (EPL) were synthesized to form hydrogels, which were non-swellable and biocompatible. The reversible modulus of the hydrogel was first achieved through the AFCT reaction; the modulus can also be regulated stepwise by changing the dose of UVA irradiation. Dynamic patterning of fluorescent markers in the hydrogel was also realized. Therefore, this dynamically controllable hydrogel has great potential as a 3D cell culture platform for tissue engineering applications.
A Non-isocyanate route to poly(ester urethane) with high molecular weight: Synthesis and effect of chemical structures of polyester-diol
Ziyun Shen, Qiyong Mei, Yi Liu, Liuchun Zhenga, Chuncheng Li, Jiajian Liu, Yaonan Xiao, Shaohua Wu and Bo Zhang
Accepted Manuscript , doi: 10.1007/s10118-021-2645-5
A series of non-isocyanate linear high molecular weight poly(ester urethane) (PETU) were prepared through an environmentally-friendly route based on dimethyl carbonate, 1,6-hexanediol and 1,6-hexanediamine. In this route, the polyurethane diol was first prepared by the reaction between Bis-1,6-hexamethylencarbamate (BHC) and 1,6-hexanediol. Series of polyester soft segment of polyurethane have been synthesized from the polycondensation of adipic acid and different diols, including butanediol, hexanediol, octanediol and decanediol. The subsequent polycondensation of polyurethane diol and polyester diol led to linear PETUs. The polymers were characterized by GPC, FT-IR, 1H NMR, 13C NMR, DSC, WAXD, TGA and tensile testing. The results indicated that PETUs possess weight-average molecular weight higher than 100, 000 and the tensile strength as high as 10 MPa. The thermal properties, crystallization behavior, micro phase separation behavior and morphology were studied by DSC and AFM, and the results indicate that degree of phase separation is affected by two factors, the crystallization and hydrogen bonding interaction between soft segment and hard segment.
Linear/branched Block Polyethylene Produced by α-Diimine Nickel(II) Catalyst and Bis(phenoxy-imine) Zirconium Binary Catalyst System in the Presence of Diethyl Zinc
Ding-ding Zhao, Yan-Hui Hou, Ke-Ning Zong, Mi-Mi Cui, Bin-Yuan Liu, Min Yang
Accepted Manuscript , doi: 10.1007/s10118-021-2629-5
In order to promote development of linear/branched block polyethylenes based on new catalytic systems, we synthesized a novel α-diimine nickel(II) complex with isopropyl substituents on ortho-N-aryl and hydroxymethyl phenyl substituents on para-N-aryl structures. The activity of α-diimine nickel(II) catalyst was 3.02106 g/molNi·h at 70 °C, and resultant polyethylene possessed 135/1000C branches. The linear/branched block polyethylenes were synthesized from ethylene polymerization catalyzed by the α-diimine nickel(II) complex/bis(phenoxy-imine) zirconium in the presence of diethyl zinc. With the addition of ZnEt2 (from 0 to 400), the melting peak of resultant polyethylene changed from a single melting peak to a bimodal melting peaks. The molecular weight of resultant polyethylene ranging from 26.8 kg/mol to 17.1 kg/mol and PDI varying gradually from 24.4 to 15.2 were obtained via adjusting ZnEt2 equiv and molar ratio of two catalysts. In addition, the branching degree of the polyethylene increased from 13/1000C to 56/1000C with the increase of the proportion of α-diimine nickel(II) catalyst. Using this binary catalyst system, the reaction temperature of chain shuttling polymerization can be carried out at 70 oC, which is more conducive to industrial application.
Safety-enhanced Polymer Electrolytes with High Ambient-temperature Lithium-ion Conductivity Based on ABA Triblock Copolymers
Dong Liu, Fan Wu, Zhihao Shen, Xinghe Fan
Accepted Manuscript , doi: 10.1007/s10118-021-2648-2
Liquid electrolytes used in lithium-ion batteries suffer from leakage, flammability, and lithium dendrites, making polymer electrolyte a potential alternative. Herein, a series of ABA triblock copolymers (ABA-x) containing a mesogen-jacketed liquid crystalline polymer (MJLCP) with a polynorbornene backbone as segment A and a second polynorbornene-based polymer having poly(ethylene oxide) (PEO) side chains as segment B were synthesized through tandem ring-opening metathesis polymerizations. The block copolymers can self-assemble into ordered morphologies at 200 oC. After doping of lithium salts and ionic liquid (IL), ABA-x self-assembles into cylindrical structures. The MJLCP segments with a high glass transition temperature and a stable liquid crystalline phase serve as physical crosslinking points, which significantly improves the mechanical performance of the polymer electrolytes. The ionic conductivity of ABA-x/lithium salt/IL is as high as 103 S cm1 at ambient temperature owing to the high IL uptake and the continuous phase of conducting PEO domains. The relationship between ionic conductivity and temperature fits the Vogel-Tamman-Fulcher (VTF) equation. In addition, the electrolyte films are flame retardant owing to the addition of IL. The polymer electrolytes with high safety and high ambient-temperature ionic conductivity developed in this work are potentially useful in solid lithium-ion batteries.
Influence of Interfacial Enantiomeric Grafting on Melt Rheology and Crystallization of Polylactide/Cellulose Nanocrystals Composites
Huagao Fang, Kangjie Yang, Qizheng Xie, Xu Chen, Shengli Wu, Yunsheng Ding
Accepted Manuscript , doi: 10.1007/s10118-021-2635-7
Incorporating the surface-grafted cellulose nanocrystals (CNCs) with enantiomeric polylactide (PLLA or PDLA) is an effective and sustainable way to modify PLLA, but their difference in promoting matrix crystallization is still unrevealed. In this paper, the CNCs with identical content and length of PLLA and PDLA (CNC-g-L and CNC-g-D) were prepared and blended with PLLA. The rheological properties of PLLA/CNC-g-D are greatly improved, indicating that the stereocomplexation can significantly improve the interfacial strength as compared with the conventional van der Waals force in PLLA/CNC-g-L. Surprisingly, the matrix crystallizes at a higher rate in PLLA/CNC-g-L than PLLA/CNC-g-D. PLLA/CNC-g-L15 reaches its half crystallinity in 8.26 min while a longer period of 13.41 min is required for PLLA/CNC-g-D15. POM observation reveals that the superior crystallization behavior in PLLA/CNC-g-L is originated from its higher nucleation efficiency and faster growth rate. The formation of low content of sc-PLA at the interface can restrict the diffusion of PLLA but contribute less to generate crystalline nuclei, which synergistically leads to the retarded crystallization kinetics in PLLA/CNC-g-D. Revealing the mechanism of different interfacial enantiomeric grafting on the melt rheology and crystallization of PLLA is of great significance for the development of high-performance polylactide materials.
Biodegradable foaming material of poly (butylene adipate-co-terephthalate) (PBAT)/poly (propylene carbonate) (PPC)
Hanlin Tian, Zepeng Wang, Shiling Jia, Hongwei Pan, Lijing Hanb, Junjia Bian, Ying Li, Huili Yang, Huiliang Zhang
Accepted Manuscript , doi: 10.1007/s10118-021-2644-6
A biodegradable blend foaming material of poly (butylene adipate-co-terephthalate) (PBAT)/poly (propylene carbonate) (PPC) was successfully prepared by chemical foaming agent and screw extrusion method. First, PBAT was modified by bis(tert-butyl dioxy isopropyl) benzene (BIBP) for chain extension, and then the extended PBAT (E-PBAT) was foamed with PPC using a twin (single) screw extruder. By analyzing the properties of the blends, we found that Young's modulus increased from 58.8 MPa of E-PBAT to 244.7 MPa of E-PBAT/PPC50/50. The viscosity of the polymer has a critical influence on the formation of cells. Compared with neat PBAT (N-PBAT), the viscosity of E-PBAT increased by 3396 Pa/s and E-PBAT/PPC 50/50 increased by 8836 Pa/s. Meanwhile, the dynamic mechanical analysis (DMA) results showed that the storage modulus (E') at room temperature increased from 538 MPa to 1650 MPa. The various phase morphologies (“sea-island”, “quasi-co-continuous” and “co-continuous”) and crystallinity of the blends affected the spread velocity of gas and further affected the foaming morphology in E-PBAT/PPC foam. Therefore, through the analysis of phase morphology and foaming mechanism, we concluded that the E-PBAT/PPC70/30 component has both excellent strength and the best foaming performance.
Controllable photoelectric properties of carbon dots and their application in organic solar cells
Wen-Sheng Zhao, Xin-Xin Li, Han Zha, Yong-Zhen Yang, Ling-Peng Yan, Qun Luo, Xu-Guang Liu, Hua Wang, Chang-Qi Ma, Bing-She Xu
Accepted Manuscript , doi: 10.1007/s10118-021-2637-5
Organic solar cells are a current research hotspot in the energy field because of their advantages of lightness, translucency, roll to roll printing and building integration. With the rapid development of small molecule acceptor materials with high-performance, the efficiency of organic solar cells has been greatly improved. Further improving the efficiency and stability of device and reducing the cost of active layer materials will contribute to the industrial development of organic solar cells. As a novel type of carbon nanomaterials, carbon dots gradually show great application potential in the field of organic solar cells due to their advantages of low preparation cost, non-toxic and excellent photoelectric performance. Firstly, the synthesis and classification of carbon dots are briefly introduced. Secondly, the photoelectric properties of CDs and their adjusting, including adjustable surface energy level structure, good film-forming performance and up/down conversion characteristics are summarized. Thirdly, based on these intrinsic properties, the feasibility and advantages of carbon dots used in organic solar cells are discussed. Fourthly, the application progress of carbon dots in the active layer, hole transport layer, electron transport layer, interface modification layer and down-conversion materials of organic solar cells is also reviewed. Finally, the application progress of carbon dots in organic solar cells are prospected. Several further research directions, including in-depth exploration of the controllable preparation of carbon dots and their application in the fields of interface layer and up/down conversion for improving efficiency and stability of device are pointed out.
Synthesis and Antibacterial Activity of Selenium-functionalized Poly(ε-caprolactone)
Yingying Li, Dong Xinga, Xiangqiang Pan, and Jian Zhu
Accepted Manuscript , doi: 10.1007/s10118-021-2638-4
A selenium-functionalized ε-caprolactone was synthesized by introducing a phenyl selenide group at the 7-position. A polymer can be obtained through the ring opening polymerization by using this compound as the monomer in a base/thiourea binary organocatalytic system. A living polymerization process was achieved under mild conditions. The resulting polymers had a controlled molecular weight with a narrow molecular weight distribution and high end-group fidelity. Random copolymers could be obtained by copolymerizing this compound with ε-caprolactone. The thermal degradation temperature of the obtained copolymers decreased with the increasing molar ratio of selenide functionalized monomer in copolymers, while the glass transition temperature increased. In addition, the phenyl selenide side group could be further modified to a polyselenonium salt, which resulted in a polymer with good antibacterial properties. The survival rate of E. coli and S. aureus was only 9% with a polymer concentration of 62.5 μg mL-1.
Optimizing Photovoltaic Performance by Kinetic Quenching of Layered Heterojunctions
Li-Feng Xu, Zhan-Wen Xu, Jia-Ping Lin, and Li-Quan Wang
Accepted Manuscript , doi: 10.1007/s10118-021-2642-8
The mixing morphology control plays a crucial role in photovoltaic power generation, yet this specific effect on device performances remains elusive. Here, we employed computational approaches to delineate the photovoltaic properties of layered heterojunction polymer solar cells with tunable mixing morphologies. One-step quench and two-step quench strategies were proposed to adjust the mixing morphology by thermodynamic and kinetic effects. The computation for the one-step quench revealed that modulating interfacial widths and interfacial roughness could significantly promote the photovoltaic performance of layered heterojunction polymer solar cells. The two-step quench can provide a buffer at a lower temperature before the kinetic quenching, leading to the formation of small-length-scale islands connected to the interface and a further increase in photovoltaic performance. Our discoveries are supported by recent experimental evidence and are anticipated to guide the design of photovoltaic materials with optimal performance.
Reactive TiO2 Nanoparticles Compatibilized PLLA/PBSU Blends: Fully Biodegradable Polymer Composites with Improved Physical, Antibacterial and Degradable Properties
Xiaoying Gu, Lingmin Hu, Zhiang Fu, Hengti Wang, Yongjin Li
Accepted Manuscript , doi: 10.1007/s10118-021-2632-x
The fully biodegradable polymer blends remain challenges for the application due to their undesirable comprehensive performance. Herein, remarkable combination of superior mechanical performance, bacterial resistance, and controllable degradability is realized in the biodegradable poly lactide/poly butylene succinate (PLLA/PBSU) blends by stabilizing the epoxide group modified titanium dioxide nanoparticles (m-TiO2) at the PLLA-PBSU interface through reactive blending. The m-TiO2 can not only act as interfacial compatibilizer but also take the role of photodegradation catalyst: on the one hand, binary grafted nanoparticles were in-situ formed and stabilized at the interface to enhance the compatibility between polymer phases. As a consequence, the mechanical properties of the blend, such as the elongation at break, notched impact strength and tensile yield strength, were simultaneously improved. On the other hand, antibacterial and photocatalytic degradation performance of the composite films was synergistically improved. It was found that the m-TiO2 incorporated PLLA/PBSU films exhibit more effective antibacterial activity than the neat PLLA/PBSU films. Moreover, the analysis of photodegradable properties revealed that that m-TiO2 nanoparticles could act as a photocatalyst to accelerate the photodegradation rate of polymers. This study paves a new strategy to fabricate advanced PLLA/PBSU blend materials with excellent mechanical performance, antibacterial and photocatalytic degradation performance, which enables the potential utilization of fully degradable polymers.
Reversible CO2-, Photo- and Thermal Triple Responsive Supramolecular Chirality of Azo-Containing Block Copolymer Assemblies Prepared by Polymerization-Induced Chiral Self-Assembly
Ya-Jing Sun, Xiao-Xiao Cheng, Teng-Fei Miao, Hao-Tian Ma, Wei Zhang and Xiu-Lin Zhu
Accepted Manuscript , doi: 10.1007/s10118-021-2647-3
Polymerization-induced chiral self-assembly (PICSA) is an efficient strategy that not only allows the construction of the supramolecular chiral assemblies in a controlled manner but also can regulate the morphology in situ. Herein, a series of azobenzene-containing block copolymer (Azo-BCP) assemblies with tunable morphologies and polymeric supramolecular chirality were obtained through the PICSA strategy. The supramolecular chirality of Azo-BCP assemblies could be regulated by carbon dioxide (CO2) stimulus, and completely recovered by bubbling with Ar. A reversible morphology transformation and chiroptical switching process could also be achieved by the alternating 365 nm UV light irradiation and heating-cooling treatment. Moreover, the polymeric supramolecular chirality is thermal-responsive and a reversible chiral-achiral switching was successfully realized, which can be reversibly repeated at least five times. This work provides a feasible strategy for constructing triple stimuli-responsive supramolecular chiral nano-objects in situ.

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2021, 39(9): 1 -8.  
Challenges and Recent Developments of Photoflow-Reversible Deactivation Radical Polymerization (RDRP)
Zhuo-Ran Zhong, Yi-Nan Chen, Yang Zhou, Mao Chen
2021, 39(9): 1069 -1083.   doi: 10.1007/s10118-021-2529-8
Photo-controlled reversible-deactivation radical polymerization (photo-RDRP) has been investigated as a “green” and spatiotemporally controlling pathway for polymer synthesis. While the combination of photo-RDRP and flow chemistry has offered opportunities to increase light intensity and enable uniform light irradiation, problems associated with flow approaches still remain for photoflow-RDRP, which has hindered merging flow polymerization with other cutting-edge techniques. Herein, we summarize challenges and recent achievements in photoflow-RDRP including the development of (a) droplet/slug-flow to regulate residence time distribution, (b) mixing techniques to tailor polymer, (c) polymerization induced self-assembly, and (d) computer-aided synthesis. We hope this work will provide informative knowledge to people in related fields and stimulate novel ideas to promote polymer synthesis in both academia and industry.
Controlled Radical Polymerization: from Oxygen Inhibition and Tolerance to Oxygen Initiation
Ning Li, Xiang-Cheng Pan
2021, 39(9): 1084 -1092.   doi: 10.1007/s10118-021-2597-9
Molecular oxygen is a radical scavenger in both conventional and controlled radical polymerization (CRP), resulting in many time-consuming methods for physically removing oxygen before the polymerization. Different approaches have been developed to have oxygen tolerance by chemically consuming or converting molecular oxygen into non-initiating species to address this issue. Recently, we propose another approach called oxygen initiation that directly transforms molecular oxygen into the initiating carbon radical in CRP. This feature article summarizes our recent developments in this direction. Oxygen-initiated reversible addition-fragmentation transfer (RAFT) polymerization has been successfully conducted using oxygen and trialkylborane as co-initiators under the ambient conditions and atmosphere without any prior degassed procedures. This gas-triggered initiation provides the opportunity for spatiotemporal control of the polymerization by molecular oxygen or air. Rationally synthesized alkylborane compounds could derive the predesigned structure of the initiating alkyl radical to minimize the side reactions and free polymer chains, achieving the synthesis of ultra-high molecular weight polymers. The challenges and perspectives are also discussed in the end.
Rational Design of Biomolecules/Polymer Hybrids by Reversible Deactivation Radical Polymerization (RDRP) for Biomedical Applications
Jie Zhou, Xiao-Yuan Zhang, Zhi-Qiang Su
2021, 39(9): 1093 -1109.   doi: 10.1007/s10118-021-2543-x
Hybrids, produced by hybridization of proteins, peptides, DNA, and other new biomolecules with polymers, often have unique functional properties. These properties, such as biocompatibility, stability and specificity, lead to various smart biomaterials. This review mainly introduces biomolecule-polymer hybrid materials by reversible deactivation radical polymerization (RDRP), emphasizing reverse addition-fragmentation chain transfer (RAFT) polymerization, and nitroxide mediated polymerization (NMP). It includes the methods of RDRP to improve the biocompatibility of biomedical materials and organisms by surface modification. The key to the current synthesis of biomolecule-polymer hybrids is to control polymerization. Besides, this review describes several different kinds of biomolecule-polymer hybrid materials and their applications in the biomedical field. These progresses provide ideas for the investigation of biodegradable and highly bioactive biomedical soft tissue materials. The research hotspots of nanotechnology in biomedical fields are controlled drug release materials and gene therapy carrier materials. Research showed that RDRP method could improve the therapeutic effect and reduce the dosage and side effects of the drug. Specifically, by means of RDRP, the original materials can be modified to develop intelligent polymer materials as membrane materials with selective permeability and surface modification.
The Application of Controlled/Living Radical Polymerization in Modification of PVDF-based Fluoropolymer
Hong-Hong Gong, Ying Zhang, Yi-Pin Cheng, Ming-Xin Lei, Zhi-Cheng Zhang
2021, 39(9): 1110 -1126.   doi: 10.1007/s10118-021-2616-x
Fluorinated polymers are important materials that are widely used in many areas as taking the advantage of inertness to chemical corrosion, prominent weather resistance, low flammability, and good thermal stability. Poly(vinylidene fluoride) (PVDF) based fluoropolymers is the most common type of commercial fluoropolymer especially used as dielectric materials. However, there are always some shortcomings in practical applications, so it is necessary to modify PVDF-based fluoropolymers for better application. Controlled/living radical polymerization (CRP) and related techniques have become a powerful approach to tailoring the chemical and physical properties of materials and have given rise to great advances in modification of PVDF-based fluoropolymers.
Enzyme-assisted Photoinitiated Polymerization-induced Self-assembly in Continuous Flow Reactors with Oxygen Tolerance
Wei-Bin Cai, Dong-Dong Liu, Ying Chen, Li Zhang, Jian-Bo Tan
2021, 39(9): 1127 -1137.   doi: 10.1007/s10118-021-2533-z
Polymerization-induced self-assembly (PISA) is an emerging method for the preparation of block copolymer nano-objects at high concentrations. However, most PISA formulations have oxygen inhibition problems and inert atmospheres (e.g. argon, nitrogen) are usually required. Moreover, the large-scale preparation of block copolymer nano-objects at room temperature is challenging. Herein, we report an enzyme-assisted photoinitiated polymerization-induced self-assembly (photo-PISA) in continuous flow reactors with oxygen tolerance. The addition of glucose oxidase (GOx) and glucose into the reaction mixture can consume oxygen efficiently and constantly, allow the flow photo-PISA to be performed under open-air conditions. Polymerization kinetics indicated that only a small amount of GOx (0.5 μmol/L) was needed to achieve the oxygen tolerance. Block copolymer nano-objects with different morphologies can be prepared by varying reaction conditions including the degree of polymerization (DP) of core-forming block, monomer concentration, reaction temperature, and solvent composition. We expect this study will provide a facile platform for the large-scale production of block copolymer nano-objects with different morphologies at room temperature.
Photoenzymatic RAFT Emulsion Polymerization with Oxygen Tolerance
Ruo-Yu Li, Ze-Sheng An
2021, 39(9): 1138 -1145.   doi: 10.1007/s10118-021-2556-5
Photoenzymatic reversible addition-fragmenatation chain transfer (RAFT) emulsion polymerization, surfactant-free or ab initio, of various monomers is reported with oxygen tolerance. In surfactant-free emulsion polymerizatoin, poly(N,N-dimethylacrylamide)s were used as stabilizer blocks for emulsion polymerization of methyl acrylate, n-butyl acrylate and styrene, producing well-defined amphiphilic block copolymers, including those with an ultrahigh molecular weight, at quantitative conversions. The controlled character of surfactant-free emulsion polymerization was confirmed by kinetic studies, chain extension studies and GPC analyses. Temporal control was demonstrated by light ON/OFF experiments. In ab initio emulsion polymerization of methyl acrylate and methyl methacrylate, low-dispersity hydrophobic polymers were synthesized with predictable molecular weights. This study extends the monomer scope suitable for photoenzymatic RAFT polymerization from hydrophilic to hydrophobic monomers and demonstrates that oxygen-tolerance can be equally achieved for emulsion polymerization with excellent RAFT control.
Dynamic Ring-chain Equilibrium of Nucleophilic Thiol-yne “Click” Polyaddition for Recyclable Poly(dithioacetal)s
Jin-Xia Lei, Qi-Yuan Wang, Fu-Sheng Du, Zi-Chen Li
2021, 39(9): 1146 -1154.   doi: 10.1007/s10118-021-2587-y
We report a dynamic polymerization system based on the reversible nucleophilic Michael polyaddition of activated alkynes and dithiols. Four poly(dithioacetal)s ( P1P4 ) were prepared via the base-catalyzed thiol-yne “click” polyaddition of two dithiols (1,4-butanedithiol ( 4S ) and 1,5-pentanedithiol ( 5S )) and two alkynones (3-butyn-2-one ( Y1 ) and 1-phenyl-2-propyn-1-one ( Y2 )) at high concentrations. We systematically investigated the base-catalyzed polymerization of 4S and Y1 (for polymer P1 ) under different conditions, and found that this polymerization was a highly concentration-dependent dynamic system: polymer P1 was formed at high concentration, while seven-membered dithioacetal, 1-(1,3-dithiepan-2-yl) propan-2-one ( C1 ), was obtained at low concentration. The polymerization of 4S and Y2 (for polymer P4 ) displayed similar polymerization behavior, generating 2-(1,3-dithiepan-2-yl)-1-phenylethanone ( C4 ) at low concentration. On the contrary, polymer P2 (from Y1 and 5S ) was exclusively obtained with no formation of eight-membered dithioacetal. The polymerizations of Y1 with 1,2-ethanedithiol ( 2S ) and 1,3-dimercaptopropane ( 3S ) only afforded corresponding five- and six-membered dithioacetals, 1-(1,3-dithiolan-2-yl) propan-2-one ( C2 ) and 1-(1,3-dithian-2-yl) propan-2-one ( C3 ). This dynamic behavior of P1 and P4 was attributed to the concentration-dependent retro-Michael addition reaction between a thiol and a β-sulfido-α,β-unsaturated carbonyl compound catalyzed by bases. Furthermore, polymers P1 and P4 could be depolymerized into C1 and C4 in yields of 58% and 95%, respectively. The ring-opening polymerization of C1 at high concentration could successfully regenerate polymer P1 . Thus, a new type of closed-loop recyclable poly(dithioacetal)s was developed.
Molar Mass Dispersity Control by Iodine-mediated Reversible-deactivation Radical Polymerization
Jin-Ying Wang, Yuan-Yuan Ni, Jian-Nan Cheng, Li-Fen Zhang, Zhen-Ping Cheng
2021, 39(9): 1155 -1160.   doi: 10.1007/s10118-021-2602-3
Dispersity (Đ) of polymers has a great effect on the properties of polymeric materials, and therefore how to control Đ is very important but still a huge challenge in polymer synthesis, especially for reversible-deactivation radical polymerization (RDRP) strategy. Herein, we successfully developed a novel strategy to adjust Đ of polymers by visible light-controlled reversible complexation mediated living radical polymerization (RCMP) and combination of single-electron transfer-degenerative chain transfer living radical polymerization (SET-DTLRP) at room temperature. In RCMP system, 2-iodo-2-methylpropionitrile (CP-I) and ethyl 2-iodo-2-phenylacetate (EIPA) were used as alkyl iodide initiators, by using methyl methacrylate (MMA) as the model monomer and n-butylacrylate (BA) as the end-capping reagent to regulate Đ of polymers. Subsequently, we successfully prepared the block copolymer PMMA-b-PBA with adjustable Đ by reactivating the polymer end-chains via SET-DTLRP in the presence of copper wire, fully demonstrating that it is a promising strategy that can keep the "living" feature of polymers while regulating their molar mass dispersities easily.
Reversible Chain Transfer Catalyzed Polymerization with Alkyl Iodides Generated from Alkyl Bromides by in Situ Halogen Exchange
Dan-Ni Gao, Yu-Lai Zhao, Jing-Yu Cai, Lin-Xi Hou, Long-Qiang Xiao
2021, 39(9): 1161 -1168.   doi: 10.1007/s10118-021-2611-2
Reversible chain transfer catalyzed polymerization (RTCP) is a practical and efficient process for the precise synthesis of polymers with special architecture by using simple phenols (2,4,6-trimethylphenol, TMP) or hydrocarbons (xanthene, XT) as efficient organocatalysts. Herein, alkyl iodide (R-I), which was generated from in situ bromine-iodine transformation of alkyl bromide (R-Br) with sodium iodide (NaI), was served as initiator to mediate RTCP with TMP or XT. MMA and other functional methacrylates, including GMA, DEAM, DMAEMA and BzMA, were successfully initiated by combining organocatalysts and azo initiators to yield polymers with low-polydispersity (Mw/Mn=1.1−1.5) and ideal monomer conversions (50%−90%) at moderate temperature. Moreover, 3-armstar polymers were also obtained by this method. The high chain-end fidelity of the obtained poly(methyl methacrylate) with iodine as chain-end group (PMMA-I) was confirmed by chain-extension reaction. The environmentally friendly initiators and organocatalysts exhibit powerful polymerization properties toward RTCP, providing a significant method to synthesize functional polymers.
Hyperbranched Azopolymer with Quadruple Responsibility
Chen Tian, Ke-Cong Zhou, Yu-Fei Lu, Jin-Jie Li, Yuan Yao, Xin-Feng Tao, Qi-Xin Zhuang, Yu-Feng Xie, Shao-Liang Lin
2021, 39(9): 1169 -1176.   doi: 10.1007/s10118-021-2576-1
Simply constructing multiple responsive polymers with obvious shape and dimension variations on their assemblies upon different stimuli is still rarely reported. In this study, we report a hyperbranched polymer named HPAzoBAHB-star-PEG9 with quadruple-response to light, temperature, pH and oxidation stimuli. The polymer contains azobenzene chromophore, sulfide, amide and amine groups in its hydrophobic hyperbranched core, and the core is capped with hydrophilic polyethylene glycol (PEG9) arms. HPAzoBAHB-star-PEG9 could assemble into unusual leaf-like lamellar micelles at 25 °C under the guidance of orderly arranged H-aggregate of azobenzene moieties. These leaf-like lamellar micelles can transform into vesicles upon UV irradiation and lower temperature, or convert to smaller spherical micelles in acidic or oxidative environments, respectively, with the destroy of ordered azobenzene arrangements. This quadruple-responsive hyperbranched polymer is suitable to construct multiple stimuli-responsive micro/nanostructures, or accurate delivery and release following subtle stimuli sequences.
Dithienylmaleimide-based D-A Conjugated Polymer Film: Photo-responsive Behavior and Application in Electrical Memory and Logic Gates
Wei Lv, Chun Wang, Xing-Chi Lin, Xiao-Fei Mei, Wen Wang, E Yang, Qi-Dan Ling, Zheng-Huan Lin
2021, 39(9): 1177 -1184.   doi: 10.1007/s10118-021-2594-z
Solid-stated smart polymers responsive to external stimuli have attracted much attention for potential application in the field of photoelectron devices, logic gates, sensor, data storage and security. However, it is a bigger challenge for polymers than that for small molecules in solid state to acquire stimuli-responsive properties, because polymers with high molecular weight are not as easy to change the packing structure as small molecules under external stimulation. Here, a D-A type alternating copolymer PTMF-o containing 3,4-bisthienylmaleimide (A unit) and fluorene (D unit) is designed and synthesized. Upon irradiation of sunlight, PTMF-o film exhibits a photo-response with the color altering from purple to colorless. It is attributed to the structure of copolymer transformed from ring-opening form (PTMF-o) to ring-closure form (PTMF-c), resulting from the oxidative photocyclization of 3,4-bisthienylmaleimide unit. Consequently, the ability of charge transfer (CT) from fluorene to 3,4-bisthienylmaleimide unit in PTMF-o can be easily weakened by light stimuli. PTMF-o film displays a WORM-type resistive storage performance for the strong CT. Interestingly, after exposure, the electrical memory behavior in situ transfers into FLASH type, due to weak CT in PTMF-c. PTMF-o film can also be employed as smart material to construct NAND and NOR logic gates by using light as input condition. The work provides a simple way to modify the electronic properties of polymers and realize stimuli-response in solid states.
DMAO-activated Rare-earth Metal Catalysts for Styrene and Its Derivative Polymerization
Zhen Zhang, Yang Jiang, Kai Zhang, Zhong-Yi Cai, Shi-Hui Li, Dong-Mei Cui
2021, 39(9): 1185 -1190.   doi: 10.1007/s10118-021-2583-2
The catalytic performance of rare-earth metal dialkyl complexes in combination with DMAO (dry methylaluminoxane) is explored. In the presence of 60 equivalents of DMAO, the half-sandwich complex (C13H8CH2Ph)Sc(CH2SiMe3)2(THF) ( 1 ) is inert for styrene polymerization, but (C5Me4Ph)Sc(CH2C6H4NMe2-o)2 ( 2 ) converts 18% styrene into syndiotactic polystyrene. Under the same conditions, the constrained-geometry configuration sandium complex (C13H8CH2Py)Sc(CH2SiMe3)2 ( 3a ) displays extremely high catalytic activity (>6420 kg·molSc−1·h−1) and perfect syndiospecific (rrrr>99%) for styrene polymerization, while its lutetium ( 3b ) and yttrium ( 3c ) analogues are nearly inactive. Although the binary catalytic system 3a /DMAO exhibits very low activity for 4-methoxystyrene polymerization, it is an efficient catalyst for the syndioselective polymerization of other styrene derivatives such as 2-methoxystyrene, 4-methylthiostyrene, 4-fluorostyrene, 4-dimethylhydrosilylstyrene, alkyne-susbstituted styrenes and 4-methylstyrene. In addition, the binary system 3a /DMAO can copolymerize ethylene and styrene to give alternating copolymers with a single glass transition at 80 °C and 0.4 MPa ethylene pressures. By increasing styrene feed amount from 20 mmol to 60 mmol, the styrene content slight increases from 48.2 mol% to 53.8 mol%, but the polymerization activity is obviously promoted from 240 kg·molSc–1·h–1 to 532 kg·molSc–1·h–1.
Fabrication of Highly Anisotropic and Interconnected Porous Scaffolds to Promote Preosteoblast Proliferation for Bone Tissue Engineering
Ya-Hui Liu, Wei Liu, Zi-Li Zheng, Xin Wei, Nouman Ali Shah, Hao Lin, Bai-Song Zhao, Shi-Shu Huang, Jia-Zhuang Xu, Zhong-Ming Li
2021, 39(9): 1191 -1199.   doi: 10.1007/s10118-021-2573-4
Mimicking the complex structure of natural bone remains a challenge for bone tissue scaffolds. In this study, a novel processing strategy was developed to prepare the bone-like scaffolds that are featured by highly oriented and fully interconnected pores. This type of biomimetic scaffolds was evolved from solid phase stretching of immiscible polycaprolactone (PCL)/poly(ethylene oxide) (PEO) blends with co-continuous structure and the pore morphology was inherited from selective extraction of water soluble PEO phase. The pore anisotropy was readily tuned by varying the stretching strain without loss of interconnectivity. Significant promotion in preosteoblast proliferation, alkaline phosphatase activity and osteogenic gene expression was observed in the oriented porous scaffolds compared to the isotropic porous counterpart. The oriented architecture provided a topographical cue for aligned growth of preosteoblasts, which activated the Wnt/β-catenin signaling pathway. The proposed strategy enriches the toolbox for the scaffold design and fabrication for bone tissue engineering.
Preparation of Low-dielectric Permittivity Polyimide Resins with High Surface Activity from Chemically Bonded Hyperbranched Polysiloxane
Xiu-Ting Li, Xiao-Meng Zhu, Jie Dong, Xin Zhao, Qing-Hua Zhang
2021, 39(9): 1200 -1210.   doi: 10.1007/s10118-021-2585-0
Thermosetting resin matrix is the key component of advanced wave-transparent composites, where low dielectric constant, excellent processability, high thermal stability, as well as good bonding ability are required for resins. Herein, we prepared a series of phenylethynyl terminated polyimide (PI) resins by grafting amine-functionalized hyperbranched polysiloxane (HBPSi) to PI chains during the in situ polymerization. The effects of HBPSi on the processability of oligomers, molecular packing, thermal stability, dielectric property and bonding ability to reinforce Kevlar fibers of the cured PI/HBPSi composite resins have been examined in detail. The dielectric constants of the cured composite resins were greatly reduced from 3.29 to 2.19 without compromising its processability and thermal stability. Meanwhile, the 10 wt% HBPSi-containing PI resin demonstrated better bonding ability to reinforce fibers with the interfacial shear strength (IFSS) of 37.64 MPa, compared with that of neat PI-6 matrix (27.34 MPa), and better adhesion to metal with the lap shear strength of 10.48 MPa, 50% higher than that of neat resin PI-6 (6.98 MPa). These resultant PI/HBPSi composite resins exhibit excellent comprehensive properties, indicating their great potential as low-dielectric constant resin matrix in radar radome.
Limited Fraction of Crystallized Side Chains in Bottlebrush Poly(n-alkyl methacrylate)s
Ming-Yue Xiang, Dong Lyu, Ling-Zhi Liu, Yong-Feng Men
2021, 39(9): 1211 -1216.   doi: 10.1007/s10118-021-2579-y
Crystallinity of bottlebrush polymers due to side chain crystallization has been considered to be related to the length of the side chains only under the assumption of complete participation of crystallization by all side chains. Recent experimental results revealed that in poly(n-alkyl methacrylate)s a fraction of side chains could not crystallize due to constraints imposed by the trapped main chain entanglements and required expansion of main chain-main chain distance. This result renders the original simplified consideration of the origin of crystallinity in bottlebrush polymers questionable. In this work, we introduce a new parameter fc, the fraction of crystallizable side chains, to better describe the crystallinity of bottlebrush polymers. A linear relationship between the melting enthalpy and the number of alkyl groups in side chains for bottlebrush polymers reported repeatedly indicates that fc remains essentially unchanged when bottlebrush polymers had the same main chain structure and grafting degree but different side chain lengths. The slope of the above-mentioned linear relationship is thus Δ\begin{document}$H_{{\rm{CH}}_2} $\end{document}×fc, where Δ\begin{document}$H_{{\rm{CH}}_2} $\end{document} stands for the melting enthalpy of one mole alkyl group packed into the crystal. With a known value of fc, it is possible to estimate the value of Δ\begin{document}$H_{{\rm{CH}}_2} $\end{document}. In case of poly(n-alkyl methacrylate)s, we estimated Δ\begin{document}$H_{{\rm{CH}}_2} $\end{document} of hexagonal crystal being at most 5.74 kJ/mol with the knowledge of possibly smallest fc of 0.67 obtained from small angle X-ray scattering data. Therefore, the crystallinity of bottlebrush polymer would be calculated based on the equation \begin{document}${X_{\rm{c}}} = {f_{\rm{c}}} \times \dfrac{{{N_{\rm{c}}}}}{N}$\end{document} with N and Nc being the number of alkyl groups in a side chain and those packed in the crystalline structure, respectively. Both chemical structure and grafting degree of bottlebrush polymers affect fc.
Self-assembly of Amphiphilic Diblock Copolymers Induced by Liquid-Liquid Phase Separation
Jia-Lu Bai, Dan Liu, Rong Wang
2021, 39(9): 1217 -1224.   doi: 10.1007/s10118-021-2563-6
The liquid-liquid phase separation (LLPS) widely exists in biology, synthetic chemistry, crystallization kinetics and other fields, and it is very important to realize the related functions. The research on the competition between LLPS and micellization/vesiculation has made considerable progress. However, the way to effectively control the formation paths from homogeneous state to aggregates has not been completely solved, which is vital to determine its structure and properties and even its future functions. Here we describe the phenomenon of LLPS and its effect on the dynamic process of self-assembly of amphiphilic diblock copolymers (BCPs). Starting from the establishment of phase diagram, we explore the existence conditions of LLPS state, the internal morphology and external size of large droplets, and its significant implications to the dynamic path of vesicle formation. Vesicles formed via LLPS have larger sized outer dimensions and inner cavities, and contain more solvents during certain stages. The detailed research of LLPS and its self-assembly simulation has contributed to completing its theoretical basis and practical applications in the future in various fields.