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Boc-phenylalanine Grafted Poly(3,4-propylenedioxythiophene) Film for Electrochemically Chiral Recognition of 3,4-dihydroxyphenylalanine Enantiomers
Jun-Long Niu, Ke-Ke Chai, Mei-Xing Zeng, Tian-Tian Wang, Chun-Yan Zhang, Shuai Chen, Jing-Kun Xu, Xue-Min Duan
In press , doi: 10.1007/s10118-019-2211-6
[Abstract](0) [PDF 2432KB](0)
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To prepare chiral monomer with single chiral center and higher stereospecificity, a pair of amino-functionalized chiral 3,4-propylenedioxythiophene (ProDOT) derivatives, chiral (3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-3-yl)methyl 2-[(tert-butoxycarbonyl)amino]-3-phenylpropanoate (ProDOT-Boc-Phe), were synthesized. Chiral poly[(3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-3-yl)methyl 2-[(tert-butoxycarbonyl)amino]-3-phenylpropanoate] (PProDOT-Boc-Phe) modified electrodes were synthesized via potentiostatic polymerization of chiral ProDOT-Boc-Phe. Chiral PProDOT-Boc-Phe films displayed good reversible redox activities. The enantioselective recognition between chiral PProDOT-Boc-Phe modified glassy carbon electrodes and DOPA enantiomers were achieved by different electrochemical technologies, including cyclic voltammetry (CV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV). (D)-PProDOT-Boc-Phe and (L)-PProDOT-Boc-Phe showed higher peak current responses toward L-DOPA and D-DOPA, respectively.
Accelerated Cutaneous Wound Healing Using an Injectable Teicoplanin-loaded PLGA-PEG-PLGA Thermogel Dressing
Wei-Ke Xu, Jing-Yu Tang, Zhang Yuan, Cai-Yun Cai, Xiao-Bin Chen, Shu-Quan Cui, Peng Liu, Lin Yu, Kai-Yong Cai, Jian-Dong Ding
In press , doi: 10.1007/s10118-019-2212-5
[Abstract](0) [PDF 2259KB](0)
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Bacterial infection is a very troublesome issue in wound treatment, which stimulates exudate formation and severely delays the healing process. Herein, a thermogelling dressing system composed of two triblock copolymers of poly(D,L-lactic acid-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(D,L-lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) with different block lengths was developed to deliver teicoplanin (TPN), a glycopeptide antibiotic, for cutaneous wound repair. The TPN-loaded thermogel was a free-flowing sol at room temperature and formed a semi-solid gel at physiological temperature. In vitro studies demonstrated that the TPN-loaded thermogel system exhibited desired tissue adhesiveness and realized the sustained release of TPN in a fast-followed-slow manner for over three weeks. Furthermore, a full-thickness excision wound model in Sprague-Dawley (SD) rats was constructed to assess the efficacy of TPN-loaded thermogel formulation. Gross and histopathologic observations implied that treatment with the thermogel formulation reduced inflammation response, promoted disposition of collagen, enhanced angiogenesis and accelerated wound closure and maturity of SD rats. The combination of the bioactivity of TPN and the acidic nature of the thermogel matrix was responsible for such an enhanced wound healing process. Consequently, the TPN-loaded PLGA-PEG-PLGA thermogel is a good candidate of wound dressing for full-thickness excision wound healing.
Positron Spectroscopy of Free Volume in Poly(vinylidene fluoride) after Helium Ions Irradiation
Jin-Zhe Lyu, Roman Laptev, Natalya Dubrova
In press , doi: 10.1007/s10118-019-2195-2
[Abstract](47) [FullText HTML](28) [PDF 607KB](6)
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Free volume is an extremely important intrinsic defect in polymers. Structurally, free volume is the randomly distributed holes in the polymer molecular chain segments. In proton exchange membrane fuel cells, free volume is also the space needed for the directional conduction of protons. Irradiation by α particles to grafting sulfonated poly(vinylidene fluoride) (PVDF) is one of the methods to produce proton exchange membrane with good proton channel rate. Positron annihilation lifetime spectroscopy was used to study the free volume size at different absorbed dose levels from 0.13 MGy to 0.65 MGy. Measurement method of positron annihilation lifetime spectroscopy for PVDF based on 44Ti positron source was developed. For low dose irradiation at 0.26 MGy, a decrease in free volume and practically unchanged crystallinity were observed. Further increase of absorbed dose range from 0.26 MGy to 0.39 MGy led to an increasing crystallinity with the same free volume level. For the absorbed dose from 0.39 MGy to 0.65 MGy, crystallinity was decreased but free volume remained almost constant.
Preparation and Characterization of UV-absorbing PVDF Membranes via Pre-irradiation Induced Graft Polymerization
Li Dong, Xiang-Dong Liu, Zheng-Rong Xiong, De-Kun Sheng, Yan Zhou, Yu-Ming Yang
In press , doi: 10.1007/s10118-019-2194-3
[Abstract](46) [FullText HTML](29) [PDF 871KB](5)
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Herein, excellent UV-absorbing poly(vinylidene fluoride) (PVDF) membranes were fabricated through the pre-irradiation induced graft polymerization method. The PVDF chains irradiated with 60Co γ-ray were modified with the polymerizable UV absorber 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole (RUVA-93). The influences of irradiation dose and monomer concentration on the prepared PVDF-g-PRUVA-93 membranes were investigated, and the optimal condition was eventually obtained. The chemical structures of the films were studied by 1H-NMR, FTIR, and XRD. UV light transmittance and DSC tests were used to characterize the UV-absorbing performance and thermal property of the PVDF films before and after modification. The results proved that the PRUVA-93 side chains were successfully incorporated into the PVDF main chains and the obtained PVDF-g-PRUVA-93 films possessed remarkable UV-absorbing property. The modified membrane made under the optimized experiment condition could completely block the UV light in the range of 200−387 nm. Additionally, the transmittance of the PVDF-g-PRUVA-93 film could be reduced to 0.04% in 280−320 nm, where the light irradiation could damage polymer materials most seriously.
Geminal Cross Coupling (GCC) Reaction for AIE Materials
Qi Yu, Ya-Long Wang, Ze-Qiang Chen, Peng-Ju Zhao, Cheng Fan, Chong Li, Ming-Qiang Zhu
In press , doi: 10.1007/s10118-019-2207-2
[Abstract](0) [FullText HTML](0) [PDF 1305KB](0)
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Tetraphenylethylene (TPE) derivatives are typical AIE molecules, having been widely investigated and applicated. The Rathore’s procedures and McMurry reaction are the two frequently used ways to synthesize the TPE derivatives. The complex processes and low tolerance of active function groups make the TPE with limited structures and properties in some degree. Very recently, a novel strategy, i.e., geminal cross coupling (GCC) reaction, is developed for designing and synthesizing various topological small molecules and polymers with rich optical properties beyond simple TPE compounds, becoming a powerful synthesis method to AIE materials. This review overviews the current progresses of AIE molecules and polymers prepared by GCC as well as their applications. We believe GCC reaction will have a bright future in the development of the next generation of tetraarylethylene (TAE)-kind AIE materials.
Thermoresponsive Fluorescent Semicrystalline Polymers Decorated with Aggregation Induced Emission Luminogens
Jia-Long Wu, Chi Zhang, Wei Qin, Da-Ping Quan, Ming-Liang Ge, Guo-Dong Liang
In press , doi: 10.1007/s10118-019-2201-8
[Abstract](27) [FullText HTML](17) [PDF 818KB](7)
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Thermoresponsive fluorescent polymers (TFPs) with unique temperature-dependent luminescent properties are of great importance for the development of new functional devices in recent years. Herein, we facilely synthesized an efficient blue-emissive polymer, abbreviated as PCB-TPE, using tetraphenylethene (TPE) as the main building block. PCB-TPE is thermally stable with a novel property of aggregation induced emission (AIE). The thermoresponsive property and mechanism of PCB-TPE were investigated. Its emission shows temperature-dependent features and reveals fine details in the thermal transitions from −10 °C to 60 °C. The polymer offers a platform for the development of efficient luminescent materials for further biological and optoelectronic applications.
Binuclear and Hexanuclear Ti(IV) Complexes Supported by [OOOO]4–-type Ligand for Preparing Disentangled UHMWPE
Vladislav A. Tuskaev, Svetlana Ch. Gagieva, Dmitry A. Kurmaev, Viktor G. Vasil'ev, Nikolay A. Kolosov, Sergey V. Zubkevich, Elena S. Mikhaylik, Evgenii K. Golubev, Galina G. Nikiforova, Pavel A. Zhizhko, Olga A. Serenko, Boris M. Bulychev
In press , doi: 10.1007/s10118-019-2197-0
[Abstract](67) [FullText HTML](8) [PDF 538KB](18)
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Binuclear and hexanuclear titanium complexes stabilized by tetradentate [OOOO]4–-type ligand were active in ethylene polymerization in the presence of Et2AlCl/Bu2Mg binary co-catalyst, giving high molecular weight polyethylene. The binuclear complex showed significantly higher catalytic activity and thermal stability in comparison to mononuclear analogue. Ultra high molecular weight polyethylene (UHMWPE) samples were processed by a solid-state uniaxial deformation into high-strength (up to 2.5 GPa) and high-modulus (over 100 GPa) oriented film tapes, which indirectly indicates a low degree of entanglements between the macromolecular chains.
1,3-Butadiene Polymerizations Catalyzed by Cobalt and Iron Dichloride Complexes Bearing Pyrazolylimine Ligands
Liang Fang, Wen-Peng Zhao, Chao Han, Chun-Yu Zhang, Heng Liu, Yan-Ming Hu, Xue-Quan Zhang
In press , doi: 10.1007/s10118-019-2198-z
[Abstract](88) [FullText HTML](34) [PDF 827KB](25)
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A series of pyrazolylimine ligated Co(II) and Fe(II) complexes with general formula of (PhC=N(C6H3(R1)2-2,6)(C3HN2(R2)2-3,5)MtCl2 (R1 = Me, R2 = H, Mt = Co (1a), Fe (2a); R1 = Me, R2 = Me, Mt = Co (1b), Fe (2b); R1 = iPr, R2 = H, Mt = Co (1c), Fe (2c); R1 = iPr, R2 = Me, Mt = Co (1d), Fe (2d); R1 = iPr, R2 = Ph, Mt = Co (1e), Fe (2e)) were synthesized and thoroughly characterized. Determined by single crystal X-ray diffraction, complexes 1b and 2b revealed dimeric structures, in which distorted trigonal bipyramid geometries were adopted for each metal centers. In the presence of ethylaluminum sesquichloride (EASC), all the cobalt complexes displayed high activities in 1,3-butadiene polymerization, affording polybutadienes with predominant cis-1,4 contents (up to 97.0%). Influences of ligand structure and polymerization parameters on catalytic performance were investigated systematically. For pyrazolylimine iron(II) dichloride complexes, the catalytic activities and microstructures of the resultant polybutadienes were highly dependent on ligand structures and polymerization conditions. For complex 2a, changing cocatalyst from trialkyl aluminums to methyl aluminoxane (MAO) led to an shift of selectivity from high cis-1,4- to trans-1,4-/1,2- manner. Being activated by MAO, complexes 2a and 2b gave trans-1,4-/1,2- binary polybutadienes, while complexes 2c, 2d, and 2e afforded cis-1,4- enriched polymers.
Preparation and Properties of High-Performance Polyimide Copolymer Fibers Derived from 5-Amino-2-(2-hydroxy-5-aminobenzene)-benzoxazole
Xue-Min Dai, Hong Gao, Ran Zhang, Zhi-Jun Du, Tong-Fei Shi, Xiang-Ling Ji, Xue-Peng Qiu, Yong-Feng Men
In press , doi: 10.1007/s10118-019-2205-4
[Abstract](0) [FullText HTML](0) [PDF 1303KB](0)
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A series of polyamic acid copolymer (co-PAAs) with para-hydroxyl groups is synthesized using two diamine monomers, namely, p-phenylenediamine (p-PDA) and 5-amino-2-(2-hydroxy-5-aminobenzene)-benzoxazole (m-pHBOA), of different molar ratios through copolymerization with 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) in N,N-dimethyacetamine (DMAc). The co-PAA solutions are used to fabricate fibers by dry-jet wet spinning, and thermal imidization is conducted to obtain polyimide copolymer (co-PI) fibers. The effects of the m-pHBOA moiety on molecular packing and physical properties of the prepared fibers were investigated. Fourier transform infrared results confirm that intra/intermolecular hydrogen bonds originate from the hydroxyl group and the nitrogen atom of the benzoxazole group and/or the hydroxyl group and the oxygen atom of the carbonyl group of cyclic imide. As-prepared PI fibers have homogenous and smooth surface and uniform diameter. The glass transition temperatures (Tgs) of PI fibers are within 311−337 °C. The polyimide fibers show 5% weight loss temperature (T5%) at above 510 °C in air. Two-dimensional wide-angle X-ray diffraction patterns indicate that the homo-PI and co-PI fibers present regularly arranged polymer chains along the fiber axial direction. The ordered molecular packing along the transversal direction is destroyed by introducing the m-pHBOA moiety. Moreover, the crystallinity and orientation factor increase with increasing draw ratio. Small-angle X-ray scattering results show that increasing the draw ratio is beneficial to reduce defects in the fibers. The resultant PI fibers exhibit excellent mechanical properties with fracture strength and initial modulus of 17.34 cN/dtex and 628.11 cN/dtex, respectively, when the molar ratio of p-PDA/m-pHBOA is 5/5 and the draw ratio is 3.0.
Substituent Effects of Pyridyl-methylene Cyclopentadienyl Rare-earth Metal Complexes on Styrene Polymerization
Zhen Zhang, Zhong-Yi Cai, Yu-Peng Pan, Yan-Li Dou, Shi-Hui Li, Dong-Mei Cui
In press , doi: 10.1007/s10118-019-2209-0
[Abstract](0) [PDF 643KB](0)
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Salt metathesis reactions between pyridyl-methylene-cyclopentadienyl lithium salt and LnCl3 followed by addition of two equivalents of LiCH2SiMe3 afforded a series of constrained-geometry-configuration rare-earth metal bis(alkyl) complexes (Cp′CH2-Py)Ln(CH2SiMe3)2(THF)n (Py = C5H4N, Cp′ = C5H4 (Cp), Ln = Sc, n = 0 (1); Cp′ = C9H6 (Ind), Ln = Sc, n = 0 (2); Cp′ = 3-Me3Si-C9H5 (3-Me3Si-Ind), Ln = Sc, n = 0 (3a), Ln = Lu (3b), Y (3c), n = 1; Cp′ = 2,7-(tBu)2C13H8 (2,7-(tBu)2-Flu), Ln = Sc (4a), n = 0, Ln = Lu (4b), Y (4c), n = 1) in moderate to good yields and characterized by NMR spectroscopy and single-crystal X-ray diffraction (for complex 3a). In the presence of [Ph3C][B(C6F5)4] and AliBu3, these complexes displayed different performances towards styrene polymerization. Rare-earth metal bis(alkyl) precursors bearing Cp, Ind and 3-Me3Si-Ind segments exhibited very low catalytic activity to afford syndiotactic polystyrene. All electron-donating tBu substituted complexes 4a, 4b and 4c showed very high activity and perfect syndiotactivity (rrrr > 99%), producing high molecular weight polystyrene (up to 54.1 × 10 4) with relatively narrow molecular distribution (PDI = 1.28~2.49).
Recent Progress in Fluorescent Vesicles with Aggregation-induced Emission
Hui Chen, Min-Hui Li
In press , doi: 10.1007/s10118-019-2204-5
[Abstract](17) [FullText HTML](2) [PDF 2712KB](2)
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Fluorescent vesicles have recently attracted increasing attention because of their potential applications in bioimaging, diagnostics and theranostics, for example, in vivo study of the delivery and the distribution of active substances. However, fluorescent vesicles containing conventional organic dyes often suffer from the problem of aggregation-caused quenching (ACQ) of fluorescence. Fluorescent vesicles working with aggregation-induced emission (AIE) offer an extraordinary tool to tackle the ACQ issue, showing advantages such as high emission efficiency, superior photophysical stability, low background interference and high sensitivity. AIE fluorescent vesicles represent a new type of fluorescent and functional nanomaterials. In this review, we summarize the recent advances in the development of AIE fluorescent vesicles. The review is organized according to the chemical structures and architectures of the amphiphilic molecules that constituting the AIE vesicles, i.e., small-molecule amphiphiles, amphiphilic polymers and amphiphilic supramolecules and supramacromolecules. The studies on the applications of these AIE vesicles as stimuli-responsive vesicles, fluorescence-guided drug release carriers, cell imaging tools and fluorescent materials based on fluorescence resonance energy transfer (FRET) are also discussed.
Synthesis of Alkyne-Functionalized Polymers via Living Anionic Polymerization and Investigation of Features during the Post-“Thiol-yne” Click Reaction
Lin-Can Yang, Li Han, Hong-Wei Ma, Pi-Bo Liu, He-Yu Shen, Chao Li, Song-Bo Zhang, Yang Li
In press , doi: 10.1007/s10118-019-2203-6
[Abstract](245) [FullText HTML](7) [PDF 7093KB](13)
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" Thiol-yne” click reaction already has wide applications in synthesis and modification of new polymer structures or novel materials due to its specific features. However, in most studies, only chain-end strategy was employed when using the di-addition feature of thiol-yne reaction while the in-chain di-addition strategy could endow us a broader space to develop the synthesis of advanced polymers. Therefore, in this paper, the features of in-chain mono- and di-addition were investigated when modifying the alkyne-functionalized polymers to prepare grafted polymers via thiol-yne click reaction. The results show that it is almost impossible to obtain the in-chain di-adducts even under excess feeding of chain-end thiol-functionalized grafts, while only the in-chain mono-adducts could be efficiently obtained. Further research investigated that controlled grafting could be encountered when carrying out the thiol-yne click reaction between chain-end alkyne-functionalized polystyrenes and chain-end thiol-functionalized polystyrenes under proper feeding. Therefore, the effect of steric-hindrance might be the primary reason for the alternative grafting via thiol-yne click reaction between in-chain and chain-end alkyne-functionalized polymers.
Influence of Chain Architectures on Crystallization Behaviors of PLLA Block in PEG/PLLA Block Copolymers
Sheng Xiang, Dong-Dong Zhou, Li-Dong Feng, Xin-Chao Bian, Gao Li, Xue-Si Chen, Tian-Chang Wang
In press , doi: 10.1007/s10118-019-2202-7
[Abstract](49) [FullText HTML](7) [PDF 922KB](9)
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The effect of the architecture of poly(ethylene glycol)/poly(L-lactide) (PEG/PLLA) block copolymers on the non-isothermal crystallization behaviors of PLLA blocks was investigated by differential scanning calorimetry (DSC) and Wide Angle X-Ray Diffraction (WAXD). 1-arm MPEG-b-PLLA and 4-arm PEG-b-PLLA (4PEG-b-PLLA) were synthesized by the ring-opening polymerization of L-lactide in the presence of Poly(ethylene glycol) methyl ether(MPEG) and 4-arm poly(ethylene glycol) (4PEG). 4-arm PLLA-b-MPEG (4PLLA-b-PEG) was synthesized by coupling of 4-arm PLLA and MPEG. The WAXD results indicated that the crystalline structure of PLLA blocks did not alter due to the different chain architectures. The average values of Avrami index ($\bar n$) were all above 4, which indicated the nucleation mechanism of PLLA blocks was heterogeneous nucleation, regardless of the architectures. The overall crystallization rates were decreased markedly as following: MPEG-b-PLLA > 4PEG- b-PLLA > 4PLLA- b-PEG, ascribed to the different confinement by PEG blocks and to the steric hindrance of chain architectures. Therefore, the crystallization of PLLA blocks become more difficult and the crystallization activation energy of the PLLA blocks increased due to the confinement of chain architectures.
Synthesis and Characterization of Easily Colored Meta-aramid Copolymer Containing Ether Bonds
Na Li, Xing-Ke Zhang, Jun-Rong Yu, Yan Wang, Jing Zhu, Zu-Ming Hu
In press , doi: 10.1007/s10118-019-2200-9
[Abstract](34) [PDF 978KB](9)
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This work described the preparation of easily colored meta-aramid (PMIA) copolymers from m-phenylenediamine (MPD), isophthaloyldichloride (IPC), and 3,4′-oxydianiline (3,4′-ODA) via solution polycondensation in N,N-dimethylacetamide (DMAc). The novel co-PMIAs were obtained in relatively high inherent viscosities ranging from 1.32 dL/g to 2.53 dL/g, which could be easily cast into flexible films with high transparence or spun into fibers. All the newly synthesized copolymers possessed excellent thermal stabilities even better than that of commercial PMIA, with 5% weight loss temperatures higher than that at 430 °C in nitrogen measured by TGA; and the glass transition temperature of 267–277 °C by was weasured DSC. The cast films exhibited good mechanical properties with a tensile strength up to 107 MPa and a tensile modulus up to 2.2 GPa. The resultant PMIAs also showed good solubility and better dye ability for cationic dyes.
Formation of Poly(ε-caprolactone) Networks via Supramolecular Hydrogen Bonding Interactions
Sen Xu, Peng-Fei Chang, Bing-Jie Zhao, Muhammad Adeel, Si-Xun Zheng
In press , doi: 10.1007/s10118-019-2199-y
[Abstract](42) [FullText HTML](14) [PDF 1361KB](6)
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In this contribution, we reported a novel approach to crosslink poly(ε-caprolactone) via supramolecular hydrogen bonding interactions. First, a series of octa-armed poly(ε-caprolactone) stars with polyhedral oligomeric silsesquioxane (POSS) cores were synthesized via the ring-opening polymerizations. Thereafter, the arm ends of organic-inorganic star-shaped PCLs were reacted with 2-(6-isocyanatohexylaminocarbonylamino)-6-methyl-4[1H]-pyrimidinone to obtain 2-ureido-4[1H]-pyrimidone (UPy)-terminated PCL stars. Notably, the UPy-terminated PCL were physically crosslinked, which was evidenced by means of dynamic mechanical thermal analysis (DMTA) and rheological analysis. Owing to the formation of the physically-crosslinked networks, the organic-inorganic PCL stars significantly displayed shape memory properties with about 100% of shape recovery, which was in marked contrast to the PCL stars without UPy termini.
Tumor Photothermal Therapy Employing Photothermal Inorganic Nanoparticles/Polymers Nanocomposites
Shu-Wei Liu, Lu Wang, Min Lin, Yi Liu, Le-Ning Zhang, Hao Zhang
In press , doi: 10.1007/s10118-019-2193-4
[Abstract](84) [PDF 1120KB](14)
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The past decade has witnessed the booming developments of the new methodologies for noninvasive tumor treatment, which are considered to overcome the current limitation of low treating efficacy, high risk of tumor recurrence and severe side effects. Among a variety of novel therapeutic methods, photothermal therapy, employing nanometer-sized agents as the heat generators under near-infrared (NIR) light irradiation to ablate tumors, gives new insights for noninvasive tumor treatments with minimal side effects. Although many nanomaterials possess photothermal effects, inorganic nanoparticles and polymers are most competitive alternatives considering the high photothermal performance and good biocompatibility. In this review, we summarized the tumor photothermal therapy using the nanocomposites composed of inorganic nanoparticles and polymers. Extinction coefficient and photothermal transduction efficiency are two main factors to evaluate the photothermal performance of nanocomposites in vitro. Considering the improvement in the stability, biocompatibility, blood circulation half-life and tumor uptake rate after polymer coating, these nanocomposites should be designed with inorganic core and polymer shell, thus improving the tumor treating efficacy in vivo. Such structure fulfills the requirements of high photothermal performance and good bio-security, making it possible to achieve complete ablation for shallow and small tumors under the safe limitation of NIR laser power density.
Neodymium Organic Sulfonate Complexes: Tunable Electronegativity/Steric Hindrance and Application in Controlled cis-1,4-polymerization of Butadiene
Jian-Yun He, Long Cui, Yan-Long Qi, Quan-Quan Dai, Chen-Xi Bai
In press , doi: 10.1007/s10118-019-2196-1
[Abstract](54) [FullText HTML](33) [PDF 713KB](6)
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Rare earth catalysts possessing characteristics of cation-anion ion pair have advantages of adjusting electronegativity and steric hindrance of metal active sites, which can better control the catalytic performance and stereoselectivity than those of traditional metallocene and Ziegler-Natta catalysts in diene polymerization. This article reports that a series of neodymium organic sulfonate complexes, Nd(CF3SO3)3·xH2yL (x, y: the coordination number; L refers to an organic electron donating ligand, such as acac (acetylacetone), IAOH (IAOH: iso-octyl alcohol), TBP (TBP: tributyl phosphate), etc.), have been synthesized, and formed cationic active species in the presence of alkylaluminum such as Al(i-Bu)3, AlEt3 and Al(i-Bu)2H, displaying high activities and distinguished cis-1,4 selectivities (up to 99.9%) for the polymerization of butadiene. The microstructures, yield, molecular weight and molecular weight distribution of the resulting polymer were controllable by adjusting electronegativity/steric hindrance of the complexes. In addition, the kinetics, active species and the possible process of polymerization have also been discussed.
The In-plane Orientation and Thermal Mechanical Properties of the Chemically Imidized Polyimide Films
Zhen-He Wang, Xing Chen, Hai-Xia Yang, Jiang Zhao, Shi-Yong Yang
In press , doi: 10.1007/s10118-019-2173-8
[Abstract](74) [FullText HTML](51) [PDF 1138KB](13)
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The thermal and mechanical properties of the chemically imidized polyimide (CIPI) films and thermally imidized polyimide (TIPI) films were investigated systematically. Experimental results indicated that the CIPI films show dramatically enhanced tensile strength and modulus with obviously reduced coefficient of thermal expansion (CTE) in comparison with TIPI films. These enhancements results from the high in-plane orientation and close packing of the CIPI backbones. Compared with thermal imidization which starts at about 140 °C, the chemical imidization activated by acetic anhydride and isoquinoline initiates the cyclization even at room temperature. The resulting imide rings restrict the mobility of polymer chains and lead to the in-plane orientation with solvent evaporation. Additionally, fewer small molecules remain in the films after treated at 120 °C by chemical imidization than by thermal imidization. The polymer chain plasticization caused by the evaporation of small molecules at high temperature is obviously restricted. Moreover, the partially imidized polymer inhibits the decomposition of mainchains that occurs at subsequent high temperature process, being beneficial to the formation of high molecular weight PI films. Hence, chemical imidization pathway shows apparent advantage to produce PI films with great combined properties, including high modulus, strength and toughness, as well as high thermal dimension stability etc.
Synthesis and Compressive Response of Microcellular Foams Fabricated from Thermally Expandable Microspheres
Rui-Zhi Zhang, Ju Chen, Mao-Wei Huang, Jian Zhang, Guo-Qiang Luo, Bao-Zhen Wang, Mei-Juan Li, Qiang Shen, Lian-Meng Zhang
In press , doi: 10.1007/s10118-019-2187-2
[Abstract](82) [FullText HTML](49) [PDF 1656KB](3)
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Cellular foams are widely applied as protective and energy absorption materials in both civil and military fields. A facile and simple one-step heating method to fabricate polymeric foams is measured by adopting thermally expandable microspheres (TEMs). The ideal foaming parameters for various density foams were determined. Moreover, a mechanical testing machine and split Hopkinson bar (SHPB) were utilized to explore the quasi-static and dynamic compressive properties. Results showed that the cell sizes of the as-prepared TEMs foams were in the micrometer range of 11 μm to 20 μm with a uniform cell size distribution. All the foams exhibited good compressive behavior under both quasi-static and high strain rate conditions, and were related to both foam densities and strain rates. The compressive strength of the TEMs foams at 8400 s−1 was up to 4 times higher than that at 10−4 s−1. The effects exerted by the strain rate and sample density were evaluated by a power law equation. With increasing density, the strain rate effect was more prominent. At quasi-static strain rates below 3000 s−1 regime, initial cell wall buckling and subsequent cellular structure flattening were the main failure mechanisms. However, in the high strain rate (HSR) regime (above 5000 s−1), the foams were split into pieces by the following transverse inertia force.
A Comparative Study on Emulsion Polymerization Processes of Styrene Initiated by Water-soluble and Oil-soluble Initiators
Xiao-Jing Liu, Yu-He Tian, Yang-Cheng Lu
In press , doi: 10.1007/s10118-019-2186-3
[Abstract](81) [FullText HTML](55) [PDF 529KB](11)
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The solubility of initiator determines its distribution and the roles played in emulsion polymerization as well as the final products, but this is still lack of systematic investigation. The present work focuses on this issue by comparing the kinetic behaviors and product properties of styrene emulsion polymerization initiated by 2,2-azoisobutyronitrile (AIBN) and potassium persulphate (KPS). Compared to KPS-initiated emulsion polymerization, the AIBN-initiated polymerization was found to be insensitive to the type of emulsifier, and have high polymerization rate as well as narrow molecular weight distribution and particle size distribution. This result indicates the effective free radicals are generated in micelles or colloids, which could decrease the proportion of homogeneous nucleation and make the process and product more controllable. As a consequence, there is a linear relationship between molecular weight of product and AIBN concentration in lg-lg coordinate. It provided a reference for the preparation of latexes with specified molecular weight and supported the possibility of the coexistence of multiple free radicals in one micelle or colloid when using oil-soluble initiator.
Rheological Properties of Polyamide: Experimental Studies and Constitutive Modeling
Cyprian Suchocki, Rafał Molak
In press , doi: 10.1007/s10118-019-2180-9
[Abstract](92) [FullText HTML](54) [PDF 15448KB](10)
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This work is focused on simulating the rheological effects in polyamide. An experimental study is carried out in order to assess such features of polyamide as: the hysteretic behavior, the strain rate dependence, and the stress relaxation. The material response in tension is investigated. Digital images correlation method (DIC) is employed in order to measure the material compressibility. A newly developed constitutive model, which was previously used to simulate the mechanical response of polyethylene subjected to moderate strains and compressive loadings, is applied to capture the large strain, inelastic behavior of polyamide in tension. The gathered experimental data are utilized to determine the values of constitutive constants of viscoelasticity and plasticity, which describe the rheological properties of polyamide. The determined material parameters are included in the text. Different strategies for evaluating the material parameters are discussed. The proposed constitutive equation is implemented into the finite element (FE) system, ABAQUS, by taking advantage of the user subroutine UMAT, which allows to define custom material laws. Some exemplary FE simulations that were used to investigate the performance of the developed subroutine are described.
Ultrathin 2D Conjugated Polymer Nanosheets for Solar Fuel Generation
Xin-Lei Zhang, Lei Wang, Liang Chen, Xiao-Yu Ma, Hang-Xun Xu
In press , doi: 10.1007/s10118-019-2171-x
[Abstract](65) [FullText HTML](31) [PDF 6827KB](2)
Abstract:
Two-dimensional (2D) polymers are fascinating as they exhibit unique physical, chemical, mechanical, and electronic properties that are completely different from those of traditional linear or branched polymers. They are very promising for applications in catalysis, separation, optoelectronics, energy storage, and nanomedicine. Recently, ultrathin 2D conjugated polymers have emerged as advanced materials for converting solar energy into chemical energy. The inherent 2D planar structure with in-plane periodicity offers many features that are highly desirable for photon-involved catalytic energy conversion processes, including high absorption coefficients, large surface areas, abundant surface active sites, and efficient charge separation. Moreover, the possibility of finely tuning the optoelectronic and structural properties through precise molecular engineering has opened up new opportunities for design and synthesis of novel 2D polymer nanosheets with unprecedented applications. Herein, we highlight recent advances in developing ultrathin 2D conjugated polymer nanosheets for solar-to-chemical energy conversion. Specifically, we discuss emerging applications of ultrathin 2D conjugated polymer nanosheets for solar-driven water splitting and CO2 reduction. Meanwhile, future challenges and prospects for design and synthesis of ultrathin 2D conjugated polymer nanosheets for solar fuel generation are also included.
Multifunctional Cholesterol-modified Dendrimers for Targeted Drug Delivery to Cancer Cells Expressing Folate Receptors
Fan-Fan Fu, Ben-Qing Zhou, Zhi-Jun Ouyang, Yi-Lun Wu, Jing-Yi Zhu, Ming-Wu Shen, Jin-Dong Xia, Xiang-Yang Shi
In press , doi: 10.1007/s10118-019-2172-9
[Abstract](76) [FullText HTML](33) [PDF 630KB](8)
Abstract:
We present here the development of cholesterol (Chol)-modified dendrimer system for targeted chemotherapy of folate (FA) receptor-expressing cancer cells. In our study, poly(amidoamine) (PAMAM) dendrimers of generation 5 (G5) were functionalized step-by-step with Chol, fluorescein isothiocyanate (FI), and FA via a poly(ethylene glycol) (PEG) spacer (PEG-FA), and then acetamide to shield their remaining surface amines. The synthesized G5.NHAc-Chol-FI-PEG-FA (for short, G5-CFPF) dendrimers were utilized to encapsulate 10-hydroxycamptothecin (HCP), a hydrophobic anticancer drug. We find that each G5-CFPF dendrimer can encapsulate 13.8 HCP molecules. The complexes show a slower release profiles of HCP in a pH-dependent manner than the control complexes formed using the same dendrimers without Chol under the same conditions. Thanks to the targeting role played by FA, the complexes display a specific inhibition efficacy to FA receptor-expressing cervical cancer cells. The designed Chol-modified dendrimers may be adopted as a promising carrier for application in targeted cancer therapy.
Improving the Thermal Conductivity and Mechanical Properties of Two-component Room Temperature Vulcanized Silicone Rubber by Filling with Hydrophobically Modified SiO2-Graphene Nanohybrids
Bo Yang, Shuang-Hong Zhang, Yi-Feng Zou, Wen-Shi Ma, Guo-Jia Huang, Mao-Dong Li
In press , doi: 10.1007/s10118-019-2185-4
[Abstract](55) [FullText HTML](51) [PDF 808KB](0)
Abstract:
The SiO2 nanoparticles were coated on the surface of graphene oxide (GO) by sol-gel method to get the SiO2-G compound. The SiO2-G was restored and oleophylically modified to prepare hydrophobic modified SiO2-G (HM-SiO2-G) which was subsequently added to silicone rubber matrix to prepare two-component room temperature vulcanized (RTV-2) thermal conductive silicone rubber. The morphology, chemical structure and dispersity of the modified graphene were characterized with SEM, FTIR, Raman, and XPS methods. In addition, the heat-resistance behavior, mechanical properties, thermal conductivity, and electrical conductivity of the RTV-2 silicone rubber were also studied systematically. The results showed that the SiO2 nanoparticles were coated on graphene oxide successfully, and HM-SiO2-G was uniformly dispersed in RTV-2 silicone rubber. The addition of HM-SiO2-G could effectively improve the thermal stability, mechanical properties and thermal conductivity of RTV-2 silicone rubber and had no great influence on the electrical insulation performance.
Preparation and Characterization of Flexible, Transparent and Thermally Stable Aromatic Co-polyamides
José Antonio Tec-Sánchez, Andrés Iván Oliva Arias, Manuel Aguilar-Vega, Juan Valerio Cauich-Rodríguez, José Luis Santiago-García
In press , doi: 10.1007/s10118-019-2190-7
[Abstract](52) [FullText HTML](35) [PDF 852KB](9)
Abstract:
Two aromatic co-polyamides were synthesized combining two diacid monomers containing bulky pendant groups, 5-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)isophthalic acid (DEAIA) and 5-tert-butylisophthalic acid (TERT), with 4,4′-(hexafluoroisopropylidene)dianiline (HFA) or 2,3,5,6-tetramethyl-1,4-phenylenediamine (Durene) by direct polycondensation. The structures of the obtained aromatic co-polyamides were confirmed by FTIR, Raman and 1H-NMR. The co-copolyamide films, DHTH and DDTD, exhibited rms-roughness values between 0.94 and 1.60 nm, respectively. Moreover, they presented good thermal stability up to 300 °C. Young’s moduli of the co-polyamide films were between 4.1 and 4.3 GPa. X-ray diffraction results showed that the co-polyamide films were amorphous due to the incorporation of both bulky pendant groups, tert-butyl and dibenzobarrelene. The combination of bulky pendant groups provided intrinsically transparent co-polyamide films with a transmittance higher than 88% in the range of 400−780 nm. Due to these outstanding film and optical properties, they are suggested to be flexible substrates in applications for solar cell and other portable electronic devices.
Study on Phase Transformation Behavior of Strain-induced PLLA Mesophase by Polarized Infrared Spectroscopy
Jian Hu, Li-Li Han, Tong-Ping Zhang, Yong-Xin Duan, Jian-Ming Zhang
In press , doi: 10.1007/s10118-019-2184-5
[Abstract](56) [FullText HTML](35) [PDF 686KB](7)
Abstract:
The structural transformation of mesophase to crystalline phase of strain-induced poly(L-lactic acid) has been investigated by differential scanning calorimetry (DSC) and in situ temperature dependent polarized Fourier transform infrared (FTIR) spectroscopy. It is found that, as the drawing temperature increases, melting of strain-induced mesophase in the heating process can remarkably interfere the crystallization behavior subsequently. Coupling with in situ polarized FTIR, from 60 °C to 76 °C, the mesophase melts partially rather than completely melting, and changes immediately to three-dimensional ordered structure. Of particular note, through monitoring the subtle spectral change in the critical phase transformation temperature from 60 °C to 64 °C, it is clearly demonstrated that relaxation of oriented amorphous chains initially takes place prior to the melting of mesophase.
Comparative Studies on Properties of Polymers with Bulky Side Groups Synthesized by Cyclopolymerization of α,ω-Dienes and α,ω-Diynes
Shao-Fei Song, Xiao-Yu Liu, Hao Zhang, Zhi-Sheng Fu, Jun-Ting Xu, Zhi-Qiang Fan
In press , doi: 10.1007/s10118-019-2183-6
[Abstract](44) [FullText HTML](34) [PDF 701KB](5)
Abstract:
Four polymers containing five-membered rings in the main chain, with or without conjugation structure along the backbone and with or without conjugated pendent groups, were designed and synthesized by metathesis cyclopolymerization of functionalized α,ω-diynes, and cyclopolymerization of functionalized α,ω-dienes catalyzed by the α-diimine palladium-based catalyst, respectively. High to moderate monomer conversions were achieved. Chain structure, molecular weight, and molecular weight distribution (MWD) of the cyclopolymerization products were characterized by 1H-, 13C-NMR, FTIR, and GPC. The polymers showed regular main chain structures, moderately high molecular weight, and narrow MWD. Thermal properties and chain stacking behaviors of the polymers were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) as well as atomic force microscopy (AFM). The polymer with conjugation system in both the backbone and the pendent groups exhibited UV-Vis absorption at a much longer wavelength than those with the conjugation only in the backbone or only in the side groups. The polymers with conjugated backbone need more space for chain stacking, and the conjugated backbone causes enhanced size of polymer particles assembled from solution. The results showed that primary microstructures of the polymer exerted significant influences on the physical properties.
Enhanced Crystallization Kinetics of PLLA by Ethoxycarbonyl Ionic Liquid Modified Graphene
Pei Xu, Zhao-Pei Cui, Gang Ruan, Yun-Sheng Ding
In press , doi: 10.1007/s10118-019-2192-5
[Abstract](44) [FullText HTML](32) [PDF 2328KB](7)
Abstract:
To investigate the performance of graphene (Gra) modified with ethoxycarbonyl ionic liquid (IL), chain mobility, and crystallization kinetics of poly(L-lactic acid) (PLLA), a series of PLLA nanocomposites have been prepared using solution-cast method. IL can improve the dispersion of Gra in PLLA matrix and the samples containing IL have higher growth rate of PLLA spherulite than neat PLLA does. PLLA/IL/Gra and PLLA/2Gra exhibit the same relaxation strength and time of αN relaxation that corresponds to the longest normal mode motion at 110−140 °C. PLLA/IL/Gra shows a faster crystallization rate than PLLA/2Gra does, which might be attributed to the Gra-imidazolium cation interaction in IL modified Gra, the significant dispersion effect of IL at Gra surface, and the increase of nuclei density of PLLA/IL/Gra.
Synthesis of Inorganic Silica Grafted Three-arm PLLA and Their Behaviors for PLA Matrix
Da-Wei Shi, Xiang-Ling Lai, Yuan-Ping Jiang, Cong Yan, Zheng-Ying Liu, Wei Yang, Ming-Bo Yang
In press , doi: 10.1007/s10118-019-2191-6
[Abstract](44) [FullText HTML](25) [PDF 994KB](12)
Abstract:
The low melt strength and poor crystallization behavior severely limit the processing and application of poly(lactic acid) (PLA) as biodegradable film materials. In this work, three-arm poly(L-lactic acid) (3A-PLLA) grafted silica nanoparticles with two kinds of topology structures were introduced into PLA matrix to improve the biodegradation performance. Different methods were used to characterize the structure of the grafted 3A-PLLA chains, the grafting density, and the thermal decomposition behavior of the nanoparticles. By varying the mass ratios of raw materials and altering the order of dropping solution in the reaction, high grafting density-tangled 3A-PLLA grafted SiO2 were synthesized as " 3A-PLLA grafting to SiO2” (GTS), while low grafting density-stretched 3A-PLLA grafted SiO2 were obtained as " SiO2 grafting to 3A-PLLA” (GTA). Topology of nanoparticles as well as the filler-matrix interaction is critically important to structure bio-nanocomposites with desirable properties. Thus, the GTS and GTA nanoparticles were introduced into PLA matrix to assess the effect. The SEM images showed the uniform dispersion of the modified nanoparticles, while the shear rheology results revealed that GTA nanoparticles made a more significant contribution on the melt-strengthening and relaxation time-extension of PLA. Moreover, it is suggested that GTA nanoparticles were more effective to act as a nucleating agent for PLA, which was certified by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) researches. All of the improvements mentioned above of GTA nanocomposites can be ascribed to stronger entanglements between 3A-PLLA stretched by nano-SiO2 and PLA matrix.
Soluble Two-dimensional Supramolecular Organic Frameworks (SOFs): An Emerging Class of 2D Supramolecular Polymers with Internal Long-range Orders
Shu-Yan Jiang, Xin Zhao
In press , doi: 10.1007/s10118-019-2189-0
[Abstract](44) [FullText HTML](20) [PDF 20332KB](2)
Abstract:
Two-dimensional (2D) materials have been demonstrated to exhibit unique properties originating from its 2D nature. In recent years, the construction of 2D materials has become a topic of great interest. This article summarizes the recent advance of 2D supramolecular organic frameworks (SOFs) which are homogeneously constructed in solution phase through self-assembly of rationally designed building blocks. These 2D SOFs are soluble and still maintain stable network structures in solutions, which exhibit uniqueness not only in structures but also in properties. In this concise review, the SOFs-related background is briefly introduced firstly, followed by outlining the research progress of soluble 2D SOFs from the perspective of monomer design, assembly, and structural characterization. The article ends with a personal outlook on the future development of this new class of supramolecular polymers.
Thermodynamics of Aromatic Cyclic Ester Polymerization in Bulk
Chong He, Xiang Zhu, Xiao-Hong Li, Xiao-Ming Yang, Ying-Feng Tu
In press , doi: 10.1007/s10118-018-2161-4
[Abstract](44) [FullText HTML](31) [PDF 515KB](11)
Abstract:
We present here the thermodynamic investigation of in situ cascade polycondensation-coupling ring-opening polymerization (PROP) for three cyclic aromatic ester monomers, i.e., cyclic oligo(2-methyl-1,3-propylene terephthalate)s (COMPTs), cyclic oligo(neopentylene terephthalate)s (CONTs) and cyclic oligo(2-methyl-2-propyl-1,3-propylene terephthalate)s (COMPPTs). The equibrium monomer to polymer weight ratio in bulk at different polymerization temperatures for each monomer was estimated by the size exclusion chromatography (SEC), and the thermodynamic parameters were estimated by Dainton equation. Quite different from the thermodynamics of aliphatic lactones polymerization, which is an exothermic process with entropy reduction, our results showed the polymerization thermodynamics for three cyclic aromatic ester monomers was a weak exothermic process with slight entropy increment, i.e., a both enthalpy and entropy driving process. Among them, CONTs showed the largest value of enthalpy change, due to its symmetric dimethyl substitution on β-position of propandiol segments.
Amorphous and Crystallizable Thermoplastic Polyureas Synthesized through a One-pot Non-isocyanate Route
Jia-Long Ban, Su-Qing Li, Chen-Feng Yi, Jing-Bo Zhao, Zhi-Yuan Zhang, Jun-Ying Zhang
In press , doi: 10.1007/s10118-018-2165-0
[Abstract](37) [FullText HTML](25) [PDF 1142KB](1)
Abstract:
A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-aminopropyl ether) and hexanediamine, m-xylylenediamine, or diethylene glycol bis(3-aminopropyl) ether at 100 °C for 6 h under normal pressure. Melt transurethane polycondensation was successively conducted at 170 °C under a reduced pressure of 399 Pa for different time periods. A series of non-isocyanate thermoplastic polyureas (NI-TPUreas) were prepared. The NI-TPUreas were characterized by gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy, and tensile test. NI-TPUreas exhibited Mn of up to 1.67 × 104 g/mol, initial decomposition temperature over 290 °C, and tensile strength of up to 32 MPa. Several crystallizable NI-TPUreas exhibited Tm exceeding 98 °C. NI-TPUreas with good thermal and mechanical properties were prepared through a green and simple one-pot non-isocyanate route.
Humidity-responsive Bilayer Actuators Comprised of Porous and Nonporous Poly(acrylic acid)/Poly(allylamine hydrochloride) Films
Miao Zheng, Tang-Jie Long, Xiao-Ling Chen, Jun-Qi Sun
In press , doi: 10.1007/s10118-018-2162-3
[Abstract](39) [FullText HTML](30) [PDF 645KB](2)
Abstract:
Bilayer humidity-responsive actuators are generally composed of actuating and supporting layers of different materials with largely different wettability. Such kinds of bilayer actuators suffer from low adhesive force between the two layers during usage. This study demonstrates the preparation of humidity-responsive bilayer actuators that have the same materials in the actuating and supporting layers to avoid the adhesive issue. The bilayer actuators consist of a porous poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) layer and a nonporous PAA/PAH layer that are fabricated by exponentially layer-by-layer assembly method. At a high/low relative humidity (RH), the nonporous PAA/PAH layer can efficiently expand/shrink by absorbing/desorbing water while the volume expansion/shrinkage of the porous PAA/PAH layer in an environment with changed humidity is significantly suppressed by the micrometer-sized pores. The largely different expansion/shrinkage of the nonporous and porous PAA/PAH layers when subjected to humidity changes enables rapid and reversible rolling/unrolling motions of the bilayer actuator. The bilayer actuator shows a faster rolling speed and a larger bending curvature when subjected to a larger humidity increase.
Modeling of the Mechanical Properties of Blend Based Polymer Nanocomposites Considering the Effects of Janus Nanoparticles on Polymer/Polymer Interface
Esmail Sharifzadeh
In press , doi: 10.1007/s10118-019-2178-3
[Abstract](29) [FullText HTML](21) [PDF 10828KB](3)
Abstract:
Blend based polymer nanocomposites, comprising Janus nanoparticles at their polymer/polymer interface, were analytically/experimentally evaluated. The modeling procedure was performed in two stages: first, modeling of polymer/polymer interface region comprising Janus nanoparticles and second, modeling of the entire systems as a function of the variation of the blend morphology. In the first stage, the modeling procedure was performed based on the development of the model proposed by Ji et al. and in the second stage, the fundamental of Kolarik’s model was used in order to propose a developed and more practical model. It was shown that Janus nanoparticles may form dual polymer/particle interphase at polymer/polymer interface which can drastically affect the final mechanical properties of the system. Comparing the results of tensile tests imposed on different prepared samples with the predictions of the model proved its accuracy and reliability (error < 9%).
Preparation and Characteristics of Poly(butylene adipate-co-terephthalate)/Polylactide Blend Films via Synergistic Efficiency of Plasticization and Compatibilization
Worasak Phetwarotai, Neeranuch Phusunti, Duangdao Aht-Ong
In press , doi: 10.1007/s10118-019-2174-7
[Abstract](41) [PDF 1067KB](1)
Abstract:
Polylactide (PLA) films blended with poly(butylene adipate-co-terephthalate) (PBAT) were hot melted using a twin screw extruder with the addition of triethyl citrate (TEC) as a plasticizer and toluene diisocyanate (TDI) as a compatibilizer. The synergistic effects of the two additives on the mechanical, thermal, and morphological properties of the PLA/PBAT blend films were investigated. The influence of TEC content on the plasticized PLA films and the effect of TDI’s presence on the PLA/PBAT blend films were also studied by comparing them with neat PLA. The results showed a pronounced increase in elongation at break of the plasticized PLA films with increasing TEC levels, but a slight reduction in thermal stability. Also, the addition of TEC and TDI to the blend system not only synergistically enhanced the tensile properties and tensile-impact strength of the PLA/PBAT blends, but also affected their crystallinity and cold crystallization rate, a result of the improvement of interfacial interaction between PLA and PBAT, including the enhancement of their chain mobility. The synergy of the plasticization and compatibilization processes led to the improvement of tensile properties, tensile-impact strength, and compatibility of the blends, accelerating cold crystallization without affecting crystallization.
Synergistic Flame-retardant Effect of Epoxy Resin Combined with Phenethyl-bridged DOPO Derivative and Graphene Nanosheets
Wei Yan, Ming-Qiu Zhang, Jie Yu, Sheng-Qiang Nie, Dai-Qin Zhang, Shu-Hao Qin
In press , doi: 10.1007/s10118-019-2175-6
[Abstract](76) [FullText HTML](37) [PDF 1071KB](11)
Abstract:
Phenethyl-bridged DOPO derivative (DiDOPO) was combined with graphene nanosheets (GNSs) in epoxy resin (EP) to improve its flame retardancy. The results indicated that the introduction of only 1.5 wt% DiDOPO/1.5 wt% GNS in EP increased the limited oxygen index (LOI) from 21.8% to 32.2%, hence meeting UL 94 V-0 rating. The thermogravimetric analyses revealed that char yield rose in presence of GNSs to form thermally stable carbonaceous char. The decomposition and pyrolysis products in gas phase were characterized by thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR), and the release of large amounts of phosphorus was detected in the gas phase. The evaluation of flame-retardant effect by cone calorimetry demonstrated that GNSs improved the protective-barrier effect of fire residue of EP/DiDOPO/GNS. The latter was further confirmed by digital photography and scanning electron microscopy (SEM). Also, Raman spectroscopy showed that GNSs enhanced graphitization degree of the resin during combustion. Overall, the combination of DiDOPO with GNSs provides an effective way for developing high-performance resins with improved flame retardancy.
Dynamic Monte Carlo Simulation on Polymerization of Encapsulant
Jin Chen, Jiong-Hua Xiang
In press , doi: 10.1007/s10118-019-2176-5
[Abstract](63) [FullText HTML](32) [PDF 1444KB](3)
Abstract:
Based on the preparative experiments of the light-emitting diode (LED) encapsulant, three types of monomer models with different functional groups are carried out to study the polymerization process by dynamic Monte Carlo (DMC) simulation and bond fluctuation model (BFM). We calculate the degree of polymerization, the radius of gyration and the frequency of void spheres to discuss the polymerization process, the molecular size and the spatial distribution at different volume fractions and proportions. Our results are in agreement with Grest’s decay rate and Flory’s scale law. Simulations show that the polymerization process depends on the appropriate volume fraction and proportion exceedingly, and the volume contraction in the polymerization process can also be observed in this study. These investigations could provide some insights into the understanding of the polymerization process of the encapsulant and help us to adjust the parameters in later experiments.
A Comparison Study of Physicochemical Properties and Stabilities of H-Shaped Molecule and the Corresponding Polymer
Quan-You Feng, Bin Li, Zong-Yan Zuo, Song-Lin Xie, Meng-Na Yu, Bin Liu, Ying Wei, Ling-Hai Xie, Rui-Dong Xia, Wei Huang
In press , doi: 10.1007/s10118-018-2152-5
[Abstract](170) [FullText HTML](81) [PDF 713KB](3)
Abstract:
Rare attention has been paid to the comparison between a monomer and its corresponding polymer in terms of the optoelectronic characteristics. In this article, a model H-shaped molecule and its corresponding polymer, both of which exhibited similar properties including blue emission and solution processing, were designed and synthesized. Optoelectronic properties and various kinds of stability features, including the thermostabilities, spectral stabilities and amplified spontaneous emission characteristic of the monomer and polymer were investigated. In general, the corresponding polymer PH exhibited similar optoelectronic properties but deteriorated stabilities compared with its H-shaped monomer H-1 probably owing to the similar chemical structure but the wider molecular weight distribution and metal catalyst residue. Importantly, monomer H-1 displayed a comparable ASE threshold value with its polymer PH, suggesting that H-shaped fluorene-based small molecules may be more promising optical gain media in solid state amplifers and lasers.
Synthesis and AO Resistant Properties of Novel Polyimide Fibers Containing Phenylphosphine Oxide Groups in Main Chain
Yong Zhao, Hong Gao, Guo-Min Li, Fang-Fang Liu, Xue-Min Dai, Zhi-Xin Dong, Xue-Peng Qiu
In press , doi: 10.1007/s10118-019-2179-2
[Abstract](70) [FullText HTML](36) [PDF 914KB](8)
Abstract:
A series of co-polyimide (PI) fibers containing phenylphosphine oxide (PPO) group were synthesized by incorporating the bis(4-aminophenoxy) phenyl phosphine oxide (DAPOPPO) monomer into the PI molecular chain followed by dry-jet wet spinning. The effects of DAPOPPO molar content on the atomic oxygen (AO) resistance of the fibers were investigated systematically. When the AO fluence increased from 0 atoms·cm−2 to 3.2 × 1020 atoms·cm−2, the mass loss of the fibers showed the dependence on DAPOPPO molar content in co-PI fibers. The PI fiber containing 40% DAPOPPO showed lower mass loss compared to those containing 0% and 20% DAPOPPO. At higher AO fluence, the higher DAPOPPO content gave rise to dense carpet-like surface of fibers. XPS results indicated that the passivated phosphate layer was deposited on the fiber surface when exposed to AO, which effectively prevented fiber from AO erosion. With the DAPOPPO content increasing from 0% to 40%, the retentions of tensile strength and initial modulus for the fibers exhibited obvious growth from 44% to 68%, and 59% to 70%, after AO exposure with the fluence of 3.2 × 1020 atoms·cm−2. The excellent AO resistance benefits the fibers for application in low Earth orbit as flexible construction components.
β-Phase Crystallization of Poly(vinylidene fluoride) in Poly(vinylidene fluoride)/Poly(ethyl methacrylate) Blends
Zi-Jie Huang, Jing Jiang, Gi Xue, Dong-Shan Zhou
In press , doi: 10.1007/s10118-019-2177-4
[Abstract](92) [FullText HTML](31) [PDF 735KB](19)
Abstract:
The nature of the crystalline phase of poly(vinylidene fluoride) (PVDF) in compatible blends with poly(ethyl methacrylate) (PEMA) was investigated by using X-ray diffraction (XRD), infrared microscopy (IR) and differential scanning calorimetry (DSC). The β phase of PVDF was observed after quenching from the melt and further annealing above the glass transition temperature over a composition range. The PVDF/PEMA blend with weight ratio of 3:2 has formed higher content of PVDF β crystals than others. By taking advantage of fast cooling rate of ultrafast differential scanning calorimeter (UFDSC), the quenching process of blends was modeled and tested simultaneously, and the melting behavior of β crystals in all blends was investigated. Three types of crystallization behavior of β phase PVDF in blends were found after quenching-annealing at different temperatures.
Perylene Diimide Based Isomeric Conjugated Polymers as Efficient Electron Acceptors for All-polymer Solar Cells
Xiao-Cheng Liu, Qing-Wu Yin, Zhi-Cheng Hu, Zhen-Feng Wang, Fei Huang, Yong Cao
In press , doi: 10.1007-S10118-019-2188-1
[Abstract](50) [FullText HTML](24) [PDF 1144KB](3)
Abstract:
We present here a series of perylene diimide (PDI) based isomeric conjugated polymers for the application as efficient electron acceptors in all-polymer solar cells (all-PSCs). By copolymerizing PDI monomers with 1,4-diethynylbenzene (para-linkage) and 1,3-diethynylbenzene (meta-linkage), isomeric PDI based conjugated polymers with parallel and non-parallel PDI units inside backbones were obtained. It was found that para-linked conjugated polymer (PA) showed better solubility, stronger π-π stacking, more favorable blend morphology, and better photovoltaic performance than those of meta-linked conjugated polymers (PM) did. Device based on PTB7-Th:PA (PTB7-Th:poly{4,8-bis[5-(2-ethylhexyl)-thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophene-4,6-diyl}) showed significantly enhanced photovoltaic performance than that of PTB7-Th:MA (3.29% vsrsus 0.92%). Moreover, the photovoltaic performance of these polymeric acceptors could be further improved via a terpolymeric strategy. By copolymerizing a small amount of meta-linkages into PA, the optimized terpolymeric acceptors enabled to enhance photovoltaic performance with improved the short-circuit current density (Jsc) and fill factor (FF), resulting in an improved power conversion efficiency (PCE) of 4.03%.
Covering the More Visible Region by Electrochemical Copolymerization of Carbazole and Benzothiadiazole Based Donor-Acceptor Type Monomers
Emine Gul Cansu-Ergun
In press , doi: 10.1007/s10118-019-2181-8
[Abstract](56) [FullText HTML](36) [PDF 896KB](7)
Abstract:
An electrochromic copolymer film of 2-(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-6-yl)-7-(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-8-yl)-9H-carbazole (M1) and 4,7-bis(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (M2) was prepared via electrochemical technique. The copolymerization was performed with one to one monomer feed ratio. Electrochemical and optical properties of the resulting copolymer film (P3) and the homopolymer films of M1 and M2 (P1 and P2) were investigated by using cyclic voltammetry and UV-Vis spectrometry techniques, and the corresponding results were compared. Incorporation of M1 and M2 into copolymer matrix was clearly observed on the resulting cyclic voltammograms and UV-Vis spectra. P3 covered the visible regions coming from both P1 and P2, and exhibited a neutral state darker color than those of homopolymers. P3 film was found to have a multichromic behavior, appearing as brown in its neutral state while changing its color upon oxidation to dark-gray (at about 0.3 V), to blue (at about 0.6 V) and finally to grayish cyan (beyond 0.9 V), with a corresponding optical band gap of 1.65 eV.
Thermo-sensitive Microgels Supported Gold Nanoparticles as Temperature-mediated Catalyst
Xian-Jing Zhou, Hai-Peng Lu, Ling-Li Kong, Dong Zhang, Wei Zhang, Jing-Jing Nie, Jia-Yin Yuan, Bin-Yang Du, Xin-Ping Wang
In press , doi: 10.1007/s10118-019-2182-7
[Abstract](121) [FullText HTML](37) [PDF 1005KB](18)
Abstract:
Microgels with a thermo-sensitive poly(N-isopropylacrylamide) (polyNIPAm) backbone and bis-imidazolium (VIM) ionic cross-links, denoted as poly(NIPAm-co-VIM), were successfully prepared. The as-synthesized ionic microgels were converted to nanoreactors, denoted as Au@PNI MGs, upon generation and immobilization of gold nanoparticles (Au NPs) of 5–8 nm in size into poly(NIPAm-co-VIM). The content of Au NPs in microgels could be regulated by controlling the 1,6-dibromohexane/vinylimidazole molar ratio in the quaternization reaction. The microgel-based nanoreactors were morphologically spherical and uniform in size, and presented reversible thermo-sensitive behavior with volume phase transition temperatures (VPTTs) at 39–40 °C. The Au@PNI MGs were used for the reduction of 4-nitrophenol, of which the catalytic activity could be modulated by temperature.
Recent advances and progress for the fabrication and surface modification of AIE-active organic-inorganic luminescent composites
Liucheng Mao, Xiaoyong Zhang, and Yen Wei
Accepted Manuscript , doi: 10.1007/s10118-019-2208-1
[Abstract](6) [PDF 1678KB](1)
Abstract:
Organic dyes based hybrid organic-inorganic luminescent nanomaterials with high quantum efficiency, good physical or chemical stability and favorable biocompatibility, have attracted growing attention recently because of their important applications in the areas of biomedical imaging, chemical sensors and light-emitting devices (LEDs). Nevertheless, conventional fluorescence molecules suffer from aggregation-caused quenching (ACQ) when they doped into inorganic nanomaterials. Aggregation-induced emission (AIE) is an abnormal and interest fluorescent phenomenon that has attracted increasing interest for various applications especially in biomedical fields. As compared with conventional organic dyes, the AIE-active molecules will emit more intense fluorescence in their aggregate or solid state. It provides an elegant route to overcome the drawbacks of conventional organic molecules. Over the past few decades, the fabrication and surface modification of various organic-inorganic luminescent composites doped with AIE-active molecules have been reported. Therefore, it is highly desirable to summarize these advances. In this review, recent advances and progress in construction various AIEgens-doped organic-inorganic hybrid nanocomposites and their subsequent surface modification were summarized. We hope this review article could further promote the research of AIE-active functional materials.
NIR Emission Nanoparticles Based on FRET Composed of AIE Luminogens and NIR Dyes for Two-Photon Fluorescence Imaging
Leijing Liu, Wen Liu, Guang Ji, Zhiyuan Wu, Bin Xu, Jun Qian, and Wenjing Tian
Accepted Manuscript , doi: 10.1007/s10118-019-2206-3
[Abstract](3) [PDF 1565KB](0)
Abstract:
Near-infrared (NIR) nanoparticles (NPs) based on fluorescence resonance energy transfer (FRET) were prepared by co-encapsulation of a red aggregation-induced emission (AIE) molecule, 2-(4-bromophenyl)-3-(4-(4-(diphenylamino)styryl)phenyl)fumaronitrile (TB), and a commercial NIR fluorescence dye, silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) (NIR775) with an amphiphilic polymer poly(styrene-co-maleic anhydride) (PSMA). The surface of the NPs, PSMA@TB/NIR775, was modified with polyethylene glycol (PEG) to increase the biocompatibility of the NPs in vivo. The PSMA@TB/NIR775 NPs show a strong NIR (780 nm) narrow emission and excellent two-photon absorption property. Moreover, the NPs exhibit good monodispersity, stability and low cytotoxicity. Under the excitation of a 1040 nm femtosecond (fs) laser, the emission peaks at 680 nm of TB and 780 nm of NIR775 excited by FRET were obtained. We utilized PSMA@TB/NIR775 NPs as fluorescent contrast agents for two-photon excited NIR microscopic imaging, and good NIR imaging effect of mouse brain vasculature was obtained with the imaging depth of about 150 µm. The FRET strategy by co-encapsulating AIE molecule and NIR dye will be helpful in preparing more narrow emission NIR probes for deep-tissue biological imaging.
Accelerated Cutaneous Wound Healing Using an Injectable Teicoplanin-Loaded PLGA-PEG-PLGA Thermogel Dressing
Wei-Ke Xu, Jing-Yu Tang, Zhang Yuan, Cai-Yun Cai, Xiao-Bin Chen, Shu-Quan Cui, Peng Liu, Lin Yu, Kai-Yong Cai, Jian-Dong Ding
Accepted Manuscript , doi: 10.1007/s10118-019-2212-5
[Abstract](10) [FullText HTML](2) [PDF 2259KB](5)
Abstract:
Bacterial infection is a very troublesome issue in wound treatment, which stimulates exudate formation and severely delays the healing process. Herein, a thermogelling dressing system composed of two triblock copolymers of poly(D,L-lactic acid-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(D,L-lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) with different block lengths was developed to deliver teicoplanin (TPN), a glycopeptide antibiotic, for cutaneous wound repair. The TPN-loaded thermogel was a free-flowing sol at room temperature and formed a semi-solid gel at physiological temperature. In vitro studies demonstrated that the TPN-loaded thermogel system exhibited desired tissue adhesiveness and realized the sustained release of TPN in a fast-followed-slow manner for over three weeks. Furthermore, a full-thickness excision wound model in Sprague-Dawley (SD) rats was constructed to assess the efficacy of TPN-loaded thermogel formulation. Gross and histopathologic observations implied that treatment with the thermogel formulation reduced inflammation response, promoted disposition of collagen, enhanced angiogenesis and accelerated wound closure and maturity of SD rats. The combination of the bioactivity of TPN and the acidic nature of the thermogel matrix was responsible for such an enhanced wound healing process. Consequently, the TPN-loaded PLGA-PEG-PLGA thermogel is a good candidate of wound dressing for full-thickness excision wound healing.
Boc-phenylalanine Grafted Poly(3, 4-Propylenedioxythiophene) Film for Electrochemically Chiral Recognition of 3,4-Dihydroxyphenylalanine Enantiomers
Jun-long Niu, Ke-ke Chai, Mei-xing Zeng, Tian-tian Wang, Chun-yan Zhang, Shuai Chen, Jing-kun Xu, and Xue-min Duan
Accepted Manuscript , doi: 10.1007/s10118-019-2211-6
[Abstract](18) [FullText HTML](2) [PDF 2432KB](2)
Abstract:
To prepare chiral monomer with single chiral center and higher stereospecificity, a pair of amino-functionalized chiral 3, 4-propylenedioxythiophene (ProDOT) derivatives, chiral (3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-3-yl)methyl 2-((tert-butoxycarbonyl)amino)-3-phenylpropanoate (ProDOT-Boc-Phe), were synthesized. Chiral poly((3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-3-yl)methyl 2-((tert-butoxycarbonyl)amino)-3-phenylpropanoate) (PProDOT-Boc-Phe) modified electrodes were synthesized via potentiostatic polymerization of chiral ProDOT-Boc-Phe. Chiral PProDOT-Boc-Phe films displayed good reversible redox activities. The enantioselective recognition between chiral PProDOT-Boc-Phe modified glassy carbon electrodes and DOPA enantiomers were achieved by different electrochemical technologies, including cyclic voltammetry (CV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV). (D)-PProDOT-Boc-Phe and (L)-PProDOT-Boc-Phe showed higher peak current responses toward L-DOPA and D-DOPA, respectively.

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Chinese Journal of Polymer Science 2018 (Volume 36) Number12  Contents
2018, 36(12): -  
[Abstract](12) [PDF 42029KB](0)
Abstract:
ARTICLE
Controlled Radical Polymerization of Styrene Mediated by Xanthene-9-thione and Its Derivatives
Hao-Yu Yu, Jiao Wang, Jian-Wei Shao, Dong Chen, Shi-Chao Wang, Li Wang, Wan-Tai Yang
2018, 36(12): 1303-1311   doi: 10.1007/s10118-018-2153-4
[Abstract](99) [FullText HTML](29) [PDF 595KB](6)
Abstract:
In our present work, a novel controlled radical polymerization system is developed based on xanthene-9-thione (XT). It was found that the radical polymerization of styrene (St) became controlled in the presence of a small amount of XT. At the early stage of the polymerization, the polymerization rate was relatively low and the as-formed polystyrene (PS) had low number-average molecular weight (Mn) and narrow polydispersity (Ð). After XT was consumed, the polymerization rate increased dramatically and the Mn of PS increased gradually with polymerization proceeding. When the polymerization of St was carried out with a proper molar ratio of initiator to XT and at an appropriate temperature, shortened slow polymerization stage and good control over Mn could be achieved. To further improve the regulating ability of XT, a series of substituent groups (―CF3, ―CH(CH3)2, ―N(CH3)2) were introduced onto the xanthene ring of XT, and the effects of these derivatives on the polymerization of St were investigated in detail. UV-Vis spectroscopy was carried out to monitor the concentration of XT during the polymerization and the chemical structure of the as-formed PS was fully characterized by 1H-NMR and ESI-MS analysis. A possible mechanism involving the formation and evolution of the cross-termination products was proposed to interpret the observed polymerization behavior.
Co-delivery of Andrographolide and Notch1-targeted siRNA to Macrophages with Polymer-based Nanocarrier for Enhanced Anti-inflammation
Teng Wu, Min Tan, Heng-Ye Gong, Yong Wang, Xin-Tao Shuai
2018, 36(12): 1312-1320   doi: 10.1007/s10118-018-2158-z
[Abstract](213) [FullText HTML](140) [PDF 831KB](10)
Abstract:
Chronic inflammatory responses induced by macrophages play a pivotal role in the progression of atherosclerosis. In the present study, a multifunctional nanocarrier based on poly(ethylene glycol)-block-poly(L-aspartic acid) grafted with diethylenetriamine, lysine and cholic acid (PEG-PAsp(DETA)-Lys-CA2) polymer was synthesized for co-delivery of andrographolide and siRNA targeting Notch1 gene to alleviate the inflammatory response in macrophages. The nanocarrier exerted low cytotoxicity as well as high performance in drug/siRNA co-delivery. In vitro studies demonstrated the co-delivery of andrographolide and Notch1 siRNA not only significantly inhibited lipopolysaccharide (LPS)-activated interleukin-6 (IL-6) and monocytes chemotactic protein 1 (MCP-1) expression as well as blocked nuclear factor-κB (NF-κB) signal activation, but also interfered the Notch1 gene expression and increased anti-inflammatory cytokines such as interleukin-10 (IL-10) and arginase-1 expression obviously in macrophages. These results suggested that the combination therapy based on Notch1 siRNA and andrographolide co-delivered nanocarrier, i.e. suppressing the expression of pro-inflammatory cytokines while simultaneously increasing anti-inflammatory factors expression, be a feasible strategy for atherosclerosis treatment.
CO2-responsive Polymeric Fluorescent Sensor with Ultrafast Response
Yun Wang, Meng Huo, Min Zeng, Lei Liu, Qi-Quan Ye, Xi Chen, Dan Li, Liao Peng, Jin-Ying Yuan
2018, 36(12): 1321-1327   doi: 10.1007/s10118-018-2167-y
[Abstract](76) [FullText HTML](28) [PDF 730KB](4)
Abstract:
Response speed is one of the most important evaluation criteria for CO2 sensors. In this work, we report an ultrafast CO2 fluorescent sensor based on poly[oligo(ethylene glycol) methyl ether methacrylate]-b-poly[N,N-diethylaminoethyl methacrylate-r-4-(2-methylacryloyloxyethylamino)-7-nitro-2,1,3-benzoxadiazole] [POEGMA-b-P(DEAEMA-r-NBDMA)], in which DEAEMA units act as the CO2-responsive segment and 4-nitrobenzo-2-oxa-1,3-diazole (NBD) is the chromophore. The micelles composed of this copolymer could disassemble in 2 s upon CO2 bubbling, accompanying with enhanced fluorescence emission with bathochromic shift. Furthermore, the quantum yield of the NBD chromophore increases with both the CO2 aeration time and the NBD content. Thus we attribute the fluorescent enhancement to the inhibition of the photo-induced electron transfer between unprotonated tertiary amine groups and NBD fluorophores. The sensor is durable although it is based on " soft” materials. These micellar sensors could be facilely recycled by alternative CO2/Ar purging for at least 5 times, indicating good reversibility.
Reversible Protein Adsorption on PMOXA/PAA Based Coatings: Role of PAA
Fatima Mumtaz, Chao-Shi Chen, Hai-Kun Zhu, Muhammad Atif, Yan-Mei Wang
2018, 36(12): 1328-1341   doi: 10.1007/s10118-018-2168-x
[Abstract](44) [FullText HTML](26) [PDF 788KB](1)
Abstract:
In this study we report design of stimuli-responsive coating based on poly(2-methyl-2-oxazoline-random-glycidyl methacrylate) (PMOXA-r-GMA) comb copolymer and poly(acrylic acid)-block-poly(glycidyl methacrylate) (PAA-b-PGMA) block copolymers and scrutinize its ability to control protein adsorption. Firstly, PMOXA/PAA based coatings were prepared by simply spin coating the mixture of PMOXA-r-GMA and PAA-b-PGMA copolymer solutions onto silicon substrates followed by annealing at 110 °C. Then coatings were rigorously characterized by X-ray photoelectron spectroscopy (XPS), the static water contact angle (WCA) test, ellipsometry and atomic force microscopy (AFM). After that, the relationship of switchable behavior of PMOXA/PAA based coatings with PAA content and chain length was investigated through the change of thickness and WCA upon pH and ionic strength (I) trigger, which indicated that the change in thickness and WCA was triggered when PAA contents were increased as well as by increasing chain length of PAA in PMOXA/PAA based coatings. Finally, real-time adsorption/desorption of lysozyme (Lyso) on PMOXA/PAA based coatings was monitored using quartz crystal microbalance with dissipation monitoring (QCM-D). The results showed that the Lyso adsorption amount was increased upon increasing chain length and contents of PAA in PMOXA/PAA based coatings. The adsorbed Lyso was then efficiently desorbed by changing pH and I of medium with the maximum desorption (> 90% desorption percentage) observed for the suitable ratio of PMOXA and PAA while chain length of PAA was kept longer than that of PMOXA. Furthermore, the prepared coatings were found to repeatedly adsorb and desorb Lyso for four successive cycles of adsorption/desorption, which confirmed the stability of prepared coatings.
Toughening Poly(lactic acid) with Imidazolium-based Elastomeric Ionomers
Lu Chen, Kuan Hu, Si-Ting Sun, Hai Jiang, Dong Huang, Kun-Yu Zhang, Li Pan, Yue-Sheng Li
2018, 36(12): 1342-1352   doi: 10.1007/s10118-018-2143-6
[Abstract](178) [FullText HTML](79) [PDF 1328KB](10)
Abstract:
Imidazolium-based elastomeric ionomers (i-BIIR) were facilely synthesized by ionically modified brominated poly(isobutylene-co-isoprene) (BIIR) with different alkyl chain imidazole and thoroughly explored as novel toughening agents for poly(lactic acid) (PLA). The miscibility, thermal behavior, phase morphology and mechanical property of ionomers and blends were investigated through dynamic mechanical analyses (DMA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile and impact testing. DMA and SEM results showed that better compatibility between the PLA and i-BIIR was achieved compared to the PLA/unmodified BIIR elastomer. A remarkable improvement in ductility with an optimum elongation at break up to 235% was achieved for the PLA/i-BIIR blends with 1-dodecylimidazole alkyl chain (i-BIIR-12), more than 10 times higher than that of pure PLA. The impact strengths of PLA were enhanced from 1.9 kJ/m2 to 4.1 kJ/m2 for the PLA/10 wt% i-BIIR-12 blend. Toughening mechanism had been established by systematical analysis of the compatibility, intermolecular interaction and phase structures of the blends. Interfacial cavitations initiated massive shear yielding of the PLA matrix owing to a suitable interfacial adhesion which played a key role in the enormous toughening effect in these blends. We believed that introducing imidazolium group into the BIIR elastomer was vital for the formation of a suitable interfacial adhesion.
The Crystallization, Melting Behaviors and Thermal Stability of Cross-linked Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Octavinyloctasilasesquioxane
Heng-Xue Xiang, Fatemeh Zabihi, Xu-Zhen Zhang, Mei-Fang Zhu
2018, 36(12): 1353-1360   doi: 10.1007/s10118-018-2157-0
[Abstract](50) [FullText HTML](27) [PDF 1018KB](1)
Abstract:
A series of cross-linked poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/octavinyloctasilasesquioxane (PHBV/OVS) composites were obtained by a simple melt reactive processing technique. Dicumyl peroxide (DCP) and OVS were employed as a free radical initiator and a cross-linking agent, respectively. The chemical structure of these produced composites were identified by 1H/13C/29Si-nuclear magnetic resonance spectroscopy (1H/13C/29Si-NMR) and Fourier transform infrared spectroscopy (FTIR). The melting behavior, non-isothermal crystallization, spherulite morphology and thermal stability property of PHBV/OVS composites were also investigated. The nucleation behaviors and crystallization rate of PHBV/OVS were significantly enhanced with the formation of cross-linked networks with different side-chains and cross-linking points. The red shift of crystalline peak temperature with addition of a small amount of OVS content evidenced the higher crystalline ability compared with the neat PHBV. However there was a threshold content, beyond which the crystallization rate weakened again. Additionally, the cross-linked structure of PHBV/OVS composites could be adjusted by changing the amount of OVS.
Antistatic PVC-graphene Composite through Plasticizer-mediated Exfoliation of Graphite
Zi-Bo Wei, Yang Zhao, Chao Wang, Shigenori Kuga, Yong Huang, Min Wu
2018, 36(12): 1361-1367   doi: 10.1007/s10118-018-2160-5
[Abstract](119) [FullText HTML](74) [PDF 1234KB](10)
Abstract:
Multilayer graphene was prepared by mechanical exfoliation of natural graphite with dioctyl phthalate (DOP) as milling medium without solvent. The obtained mixture could be directly mixed with poly(vinyl chloride) (PVC) for melt-forming, with DOP acting as plasticizer and graphene acting as conductive filler for antistatic performance. The composite showed surface resistance of 2.5 × 106 Ω/□ at 1 wt% carbon additive, significantly lower than approx. 7 wt% of raw graphite required for achieving the same level. This value is low enough for practical antistatic criterion of 3 × 108 Ω/□. The effect of filler addition on mechanical performance was minimal, or even beneficial for the milled carbon in contrast to the case of raw graphite.
Light Electrospun Polyvinylpyrrolidone Blanket for Low Frequencies Sound Absorption
Joshua Avossa, Francesco Branda, Francesco Marulo, Giuseppe Petrone, Stefano Guido, Giovanna Tomaiuolo, Aniello Costantini
2018, 36(12): 1368-1374   doi: 10.1007/s10118-018-2154-3
[Abstract](54) [FullText HTML](28) [PDF 704KB](1)
Abstract:
Light polymeric soundproofing materials (density = 63 kg/m3) of interest for the transportation industry were fabricated through electrospinning. Blankets of electrospun polyvinylpyrrolidone (average fiber diameter = (1.6 ± 0.5) or (2.8 ± 0.5) µm) were obtained by stacking disks of electrospun mats. The sound absorption coefficients were measured using the impedance tube instrument based on ASTM E1050 and ISO 10534-2. For a given set of disks (from a minimum of 6) the sound absorption coefficient changed with the frequency (in the range 200–1600 Hz) following a bell shape curve with a maximum (where the coefficient is greater than 0.9) that shifts to lower frequencies at higher piled disks number and greater fiber diameter. This work showed that electrospinning produced sound absorbers with reduced thickness (2–3 cm) and excellent sound-absorption properties in the low and medium frequency range.
Carbon Fibers Decorated by Polyelectrolyte Complexes toward Their Epoxy Resin Composites with High Fire Safety
Xiao-Hui Shi, Li Chen, Bo-Wen Liu, Jia-Wei Long, Ying-Jun Xu, Yu-Zhong Wang
2018, 36(12): 1375-1384   doi: 10.1007/s10118-018-2164-1
[Abstract](144) [FullText HTML](72) [PDF 1370KB](28)
Abstract:
The achievement of both robust fire-safety and mechanical properties is of vital requirement for carbon fiber (CF) composites. To this end, a facile interfacial strategy for fabricating flame-retardant carbon fibers decorated by bio-based polyelectrolyte complexes (PEC) consisting of chitosan (CH) and ammonium polyphosphate (APP) was developed, and its corresponding fire-retarded epoxy resin composites (EP/(PEC@CF)) without any other additional flame retardants were prepared. The decorated CFs were characterized by SEM-EDX, XPS and XRD, indicating that the flame-retardant PEC coating was successfully constructed on the surface of CF. Thanks to the nitrogen- and phosphorous-containing PEC, the resulting composites exhibited excellent flame retardancy as the limiting oxygen index (LOI) increased from 31.0% of EP/CF to 40.5% and UL-94 V-0 rating was achieved with only 8.1 wt% PEC. EP/(PEC8.1@CF) also performed well in cone calorimetry with the decrease of peak-heat release rate (PHRR) and smoke production rate (SPR) by 50.0% and 30.4%, respectively, and the value of fire growth rate (FIGRA) was also reduced to 3.41 kW·m−2·s−1 from 4.84 kW·m−2·s−1, suggesting a considerably enhanced fire safety. Furthermore, SEM images of the burning residues revealed that the PEC coating exhibited the dominant flame-retardant activity in condensed phase via the formation of compact phosphorus-rich char. In addition, the impact strength of the composite was improved, together with no obvious deterioration of flexural properties and glass transition temperature. Taking advantage of the features, the PEC-decorated carbon fibers and the relevant composites fabricated by the cost-effective and facile strategy would bring more chances for widespread applications.
Preparation of Polylactide Composite with Excellent Flame Retardance and Improved Mechanical Properties
Chu-Bo Sun, Hong-Da Mao, Feng Chen, Qiang Fu
2018, 36(12): 1385-1393   doi: 10.1007/s10118-018-2150-7
[Abstract](153) [FullText HTML](70) [PDF 748KB](7)
Abstract:
Despite the good biodegradable and mechanical properties, poly(lactic acid) still suffers from a highly inherent flammability, which restricts its applications in the electric and automobile fields. In order to improve the flame retardancy of PLA, in this work, melamine polyphosphate (MPP) and zinc bisdiethylphosphinate (ZnPi) were firstly incorporated into PLA, and the synergistic effect of them on flame retardance of PLA was investigated using limiting oxygen index (LOI), UL-94 vertical measurement, scanning electron microscopy (SEM) and cone calorimeter tests etc. The results showed that PLA composite with 15 wt% of MPP/ZnPi (3:2) had the best flame-retardant efficiency with LOI value of 30.1 and V0 rating in UL-94 tests, which was far better than using MPP or ZnPi alone. What is more, although a wide range of flame retardants have been developed to reduce the flammability, so far, they normally compromise the mechanical properties of PLA. On the premise of maintaining good flame-retardant performance, we improved the toughness of flame-retardant PLA composite, and the impact strength of flame-retardant PLA composite was more than tripled (8.08 kJ/m2) by adding thermoplastic urethanes (TPU). This work offers an innovative method for the design of the unique integration of extraordinary flame retardancy and toughening reinforcement for PLA materials.
Mesoscopic Simulation Assistant Design of Immiscible Polyimide/BN Blend Films with Enhanced Thermal Conductivity
Guo-Dong Zhang, Lin Fan, Lan Bai, Min-Hui He, Lei Zhai, Song Mo
2018, 36(12): 1394-1402   doi: 10.1007/s10118-018-2155-2
[Abstract](52) [FullText HTML](28) [PDF 1601KB](1)
Abstract:
The mesoscopic simulation technique was applied to describe the phase separation behavior of polyimide blends and used for design of immiscible polyimide/BN blend films with enhanced thermal conductivity. The simulation equilibrium morphologies of different poly(amic acid) (PAA) blend systems were investigated and compared with optical images of corresponding polyimide blend films obtained by experiment. The immiscible polyimide blend films containing nano-/micro-sized BN with vertical double percolation structure were prepared. The result indicated that the thermal conductivity of polyimide blend film with 25 wt% nano-sized BN reached 1.16 W/(m·K), which was 236% increment compared with that of the homogenous film containing the same BN ratio. The significant enhancement in thermal conductivity was attributed to the good phase separation of polyimide matrix, which made the inorganic fillers selectively localized in one continuous phase with high packing density, consequently, forming the effective thermal conductive pathway.