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Ultrasmall Nanoparticles Diluted Chain Entanglement in Polymer Nanocomposites
Sheng-Chao Chai, Tian-Yang Xu, Xiao Cao, Gang Wang, Quan Chen, Hao-Long Li
In press , doi: 10.1007/s10118-019-2262-8
[Abstract](81) [FullText HTML](32) [PDF 1599KB](24)
Nanoparticle-polymer composites exhibit unusual mechanical properties and chain dynamics when the nanoparticle size is smaller than the entanglement mesh size of the matrix polymer chains, corresponding to the ultrasmall regime defined by de Gennes. However, the mechanism is still ambiguous due to the lack of suitable model systems. Here, we develop an ultrasmall nanoparticle system by using a bimodal grafting strategy to graft both short alkyl chains and long polystyrene chains onto the polyoxometalate molecular nanoparticles with a tunable repulsive potential between the nanoparticles, thus facilitating their uniform dispersion in polystyrene matrices. Linear viscoelasticity of the resultant nanocomposites changes with increasing the filler content, which shows a decrease in both plateau modulus and terminal relaxation time, indicative of a dilution effect of the nanoparticles. Namely, the entanglement network becomes sparser with increasing the filler content.
Amphiphilic Dendrimer-like Copolymers with High Chain Density by Living Anionic Polymerization
Ke Zheng, Jun-Po He
Corrected proof , doi: 10.1007/s10118-019-2247-7
[Abstract](82) [FullText HTML](19) [PDF 2749KB](8)
We report here a method for the preparation of amphiphilic dendrimer-like copolymers with dendritic polystyrene (PS) core and protonated poly(2-vinyl pyridine) (P2VP) or poly(methacrylic acid) (PMAA) shell. The method employed the efficient coupling reaction of anionic living polymer chains and chlorosilane. The synthesis started from a functionalized 3rd generation dendritic polystyrene, G3PS-g-SiCl, used as the precursor. The dendrimer-like copolymer of styrene and 2-vinyl pyridine, G3PS-g-P2VP, was synthesized by direct coupling of living P2VPLi to the precursor. The dendrimer-like copolymer of styrene and tert-butyl methacrylate, G3PS-g-PtBMA, was synthesized by an indirect procedure in which a living polymer containing mainly PtBMA segment was attached to the precursor. Both methods resulted in the formation of dendrimer-like copolymers with the high molecular weights (up to 8.5 × 106 Da), large molecular sizes (diameter up to 73 nm), and dense shells (number of arms up to 1300). These products, G3PS-g-P2VP and G3PS-g-PtBMA, were protonated with trifluoroacetic acid and acidic hydrolyzed, respectively. After transformation, amphiphilic dendrimer-like copolymers, G3PS-g-P2VPH+ and G3PS-g-PMAA, were obtained. Preliminary results on the solution properties of the amphiphilic products were presented.
Controlling Heat Transfer for the Manufacturing of High Molecular Weight Polyisobutylene via Formation of Micelles
Szilard Csihony, Nicole Janssen, Klaus Mühlbach
Corrected proof , doi: 10.1007/s10118-019-2250-z
[Abstract](60) [FullText HTML](28) [PDF 553KB](12)
An alternative cationic polymerization method is developed to produce high molecular weight polyisobutylene (HM-PIB) with molecular weights above 5 × 105 g/mol. The method involves micelle formation via functionalized low molecular weight polyisobutylene (LM-PIB) in non-polar solvent. One end of LM-PIB is modified with an imidazolium-containing ionic group, which together with the anion (e.g. Al2Cl7) works as Lewis acid. While the monomer isobutylene dissolves readily in non-polar solvent, polymerization can occur only within the micelle, which affords stable HM-PIB particles. HM-PIB with a molecular weight (MW) close to 1 × 106 g/mol was produced successfully with the described method.
Degradable Protein-loaded Polymer Capsules Fabricated by Thiol-disulfide Cross-linking Reaction at Liquid-liquid Interface
Xiaoteng Ma, Guangda Han, Hanying Zhao
Corrected proof , doi: 10.1007/s10118-019-2253-9
[Abstract](87) [FullText HTML](42) [PDF 795KB](4)
In these years, the encapsulation of proteins for protection and delivery purpose has attracted great interest. In this research, W/O emulsion droplets were used as soft templates and bovine serum albumin (BSA) encapsulated hollow capsules were prepared by liquid-liquid interfacial thiol-disulfide exchange reaction. Block copolymer chains with pendant pyridyl disulfide groups are located at liquid-liquid interface, and upon addition of a macromolecular crosslinking agent with multiple pendant thiol groups into an emulsion, thiol-disulfide interfacial crosslinking reactions lead to the formation of BSA encapsulated hollow capsules. The cleavage of disulfides on the membranes results in the degradation of hollow structures and the release of encapsulated protein molecules. Transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and confocal laser scanning microscopy were employed to characterize the hollow capsules. In comparison with native BSA, BSA molecules encapsulated in the hollow structures show higher catalytic efficiency due to higher local concentration of reactants in the structures. The membranes of the hollow capsules can efficiently protect the encapsulated BSA from hydrolysis by trypsin.
Research on the Glass Transition Temperature and Mechanical Properties of Poly(vinyl chloride)/Dioctyl Phthalate (PVC/DOP) Blends by Molecular Dynamics Simulations
Jing Li, Shao-Hua Jin, Guan-Chao Lan, Zi-Shuai Xu, Lu-Ting Wang, Na Wang, Li-Jie Li
Corrected proof , doi: 10.1007/s10118-019-2249-5
[Abstract](94) [FullText HTML](28) [PDF 624KB](16)
To effectively improve the performance and expand the applications of polymers, molecular dynamics (MD) simulations with the COMPASS force field have been applied to predict the miscibility, glass transition temperature (Tg), and mechanical properties of poly(vinyl chloride)/dioctyl phthalate (PVC/DOP) blends. The solubility parameter values obtained are in good agreement with the reference data and the little difference (|Δδ| < 2.0 MPa0.5) between two components indicates that PVC/DOP is a miscible system. Tg is predicted by the slope of the free volume and density versus temperature simulation data based on density and free volume theory which is agree well with the experimental data. In addition, the analyses of mechanical properties results indicate that the values of Young’s modulus (E), bulk modulus (K), and shear modulus (G) decrease with the addition of DOP, demonstrating that the rigidity of material is weakened and the ductility is improved. The mechanical properties can also be effectively improved by increasing the temperature, which may provide a more flexible mixture, with lower E, K, G but an increased ductility.
Effect of Molybdenum Disulfide Exfoliation Conditions on the Mechanical Properties of Epoxy Nanocomposites
Bin Chen, Bao-Jia Ni, Meng-Xiang Fu, Hang Zhong, Wei-Feng Jiang, Si-Yuan Liu, He-Xin Zhang, Keun-Byoung Yoon
Corrected proof , doi: 10.1007/s10118-019-2239-7
[Abstract](80) [FullText HTML](43) [PDF 725KB](9)
In this work, the MoS2 fillers were prepared through chemical exfoliation method and used as fillers to fabricate epoxy (EP)/MoS2 nanocomposites. The effects of molybdenum disulfide (MoS2) intercalation conditions on the properties of EP/MoS2 nanocomposites were investigated. As the intercalation time was prolonged, the surface of MoS2 exhibited a totally crumpled structure and more functional groups formed. Because of the higher functional group concentration, the interfacial adhesion force between EP and MoS2 was enhanced. With the addition of 1.0 wt% exfoliated MoS2 fillers, the tensile strength and tensile modulus of EP were even improved ~500% and ~6800%, respectively. Therefore, this work provides a facile way to produce high-performance EP nanocomposites.
Poly(1-vinylimidazole) Prospects in Gene Delivery
Elena N. Danilovtseva, Stanislav N. Zelinskiy, Viktor A. Pal'shin, Gayathri Kandasamy, Uma Maheswari Krishnan, Vadim V. Annenkov
Corrected proof , doi: 10.1007/s10118-019-2240-1
[Abstract](56) [FullText HTML](23) [PDF 1638KB](8)
Polymeric amines are being studied intensively as components of systems for gene delivery in genetic engineering and gene therapy of genetic disorders, including cancer. Despite remarkable achievements in the field, polymeric amines, such as polyethyleneimine, show some disadvantages. Strong interaction between the amine-containing polymer and nucleic acid hampers the release of nucleic acid in the cell cytoplasm. Amine groups can interact with the cell membrane which results in cell death. These limitations of polymeric amines stimulated an investigation of new structures for gene delivery. Imidazole-containing polymers have attracted attention as lesser basic substances, while they are able to interact with polymeric acids. Further development of imidazole-based gene delivery agents requires knowledge about some fundamental aspects of interaction between nucleic acids, and polymeric imidazoles. In this work, we studied the complexation of poly(1-vinylimidazole) and oligomeric DNA. We found that the number of active sites capable of binding with negatively charged phosphate groups is comparable with the number of protonated imidazole units in the case of high molecular weight polymer. The increase in polymer charge by 1-bromopropane quaternizating 1%−5% imidazole units or by decreasing the pH to 6.5−7 considerably increased the ability of poly(1-vinylimidazole) to interact with oligonucleotides. The pH sensitivity of this interaction is interesting for cancer gene therapy because the tumours have a lowered intercellular pH (stable oligonucleotide complex) and a higher extracellular pH which can lead to complex dissociation. Minimal critical length for complexation of quaternized poly(1-vinylimidazole) and DNA is below eight units which corresponds to polymers with amine groups. Fluorescence-tagged poly(1-vinylimidazole) samples were obtained and their potential for monitoring the polymer and polymer-oligonucleotide complex internalization into living cells was demonstrated.
Self-healing Behavior of Ethylene Propylene Diene Rubbers Based on Ionic Association
Zhi-Fei Zhang, Kun Yang, Shu-Gao Zhao, Lai-Na Guo
Corrected proof , doi: 10.1007/s10118-019-2241-0
[Abstract](37) [FullText HTML](30) [PDF 772KB](3)
To meet the increasing demand for safe, environmentally friendly and high-performance smart materials, self-healing rubbers are highly desired. Here, the self-healing performance of ethylene propylene diene monomer rubber (EPDM) is reported, which was designed by graft-polymerization of zinc dimethacrylate (ZDMA) onto rubber chains to form a reversible ionic cross-linked network. Single ionic cross-linked network and dual network, combining covalent and ionic cross-links, could be tuned by controlling vulcanization process to achieve tailorable mechanical and self-healing properties. It was found that ionic cross-linked EPDM showed a recovery of more than 95% of the original mechanical strength through a healing process of 1 h at 100 °C. The covalent cross-links could improve mechanical properties but block self-healing. Adding 50 wt% liquid rubber to " dry” EPDM could effectively enhance self-healing capability of the dual cross-linked network and the healed tensile strength could reach 0.9 MPa. A compromise between mechanical performance and healing capability could be potentially tailored by controlling vulcanization process and liquid rubber content.
Neodymium-catalyzed Polymerization of C5 Fraction: Efficient Synthesis of 1,3-Pentadiene-isoprene Copolymer Rubbers
Jin-Yan Hou, Fang Guo, Qian Hu, Yang Li, Zhao-Min Hou
Corrected proof , doi: 10.1007/s10118-019-2244-x
[Abstract](53) [FullText HTML](28) [PDF 766KB](4)
The polymerization of C5 fraction without separation and concentration by using a commercial available Nd(P204)3/AliBu3/AlEt2Cl has afforded for the first time a new kind of 1,3-pentadiene-isoprene random copolymers as rubber materials. Isoprene (IP) and E-1,3-pentadiene (EPD) acted as polymerization monomers, cyclopentadiene acted as poison, and other substances like alkanes, monoolefins, Z-1,3-pentadiene acted as solvents in this multicomponent C5 fraction polymerization system. The data of kinetic experiments, NMR, and DSC indicated that the polymerization of C5 fraction by Nd(P204)3/AliBu3/AlEt2Cl afforded the IP-EPD random copolymers. By controlling polymerization conditions such as [Al]/[Nd]/[Cl] molar ratio and polymerization temperature, the random EPD-IP copolymers containing high cis-1,4-poly(IP) (with selectivity 96%) and moderate cis-1,4-poly(EPD) (with selectivity 60%) units with a low glass transition temperature (about −60 °C), controllable molecular weight (Mn = 3.8 × 104‒14.3 × 104), and moderate molecular weight distribution (Mw/Mn = 2.17‒2.78) were obtained in a high yield.
Dispersion of Titanium(IV) Oxide Nanoparticles in Mixed Matrix Membrane Using Octaisobutyl Polyhedral Oligomeric Silsesquioxane for Enhanced CO2/CH4 Separation Performance
Grace Ying En Tan, Pei Ching Oh, Kok Keong Lau, Siew Chun Low
Corrected proof , doi: 10.1007/s10118-019-2246-8
[Abstract](68) [FullText HTML](14) [PDF 1418KB](9)
Titanium(IV) oxide (TiO2) nanoparticles have been incorporated into mixed matrix membranes (MMMs) to improve gas separation performance. However, TiO2 nanoparticles tend to agglomerate due to high surface energy and van der Waals forces. This leads to precipitation which causes the formation of non-homogeneous MMM morphology. In this study, the effect of octaisobutyl polyhedral oligomeric silsesquioxane (POSS) addition on TiO2/polysulfone MMM was investigated. The aims are to enhance gas separation performance whilst preventing agglomeration of TiO2 nanoparticles. The results demonstrated that inclusion of POSS as dispersant increases MMMs’ CO2/CH4 selectivity and permeance, possibly due to less void formation and more evenly distributed pore structure. For example, synergistic addition of 5 wt% TiO2 and 5 wt% POSS increased the CO2/CH4 selectivity up to 390% compared to MMM without POSS. This is supported by elemental mapping of titanium which revealed that POSS successfully dispersed TiO2 nanoparticles and prevented aggregation. TiO2-POSS/PSf MMMs also retained their favorable thermal stability.
Synthesis of Conjugated Polymers Containing Diketopyrrolopyrrole (DPP) Building Block and the Photophysical Study
Ying-Zhong Wu, Yi-Chen Zhang, Jia-Jun Chen, Li-Juan Fan
Corrected proof , doi: 10.1007/s10118-019-2248-6
[Abstract](82) [FullText HTML](26) [PDF 725KB](13)
Sonogashira coupling of two different diketopyrrolopyrrole (DPP)-containing dihaloarenes with the same aromatic bisalkyne resulted in two new conjugated polymers with the same backbone but different pendant groups on the DPP moiety. The polymers were found to have designed chemical structures via structural characterizations in comparison with three monomers. The molecular weight measurement further demonstrated the formation of polymers with polydispersity index around 2, consistent with the polycondensation nature of the polymerization based on Sonogashira coupling. Both polymers could dissolve in many organic solvents, and the one with long alkyl side group on DPP moiety had better solubility. Photophysical investigation showed that both polymers had typical absorption/emission of conjugated polymers, and varying the solvent did not have large influence. Compared with other polar solvents, toluene reduced the quantum yield of fluorescence of the polymers, especially for the one with long alkyl pedant group, accompanying with slight red-shift in absorption/emission. The difference in the absorption/emission wavelengths between the polymers was similar to that between the corresponding monomers. Adding water into the THF solution of polymers reduced the emission intensity but no red-shift was observed. Discussion about the structure-property relationships was carried out in detail.
Preparation of Ultralow Molecular Weight Poly(vinyl chloride) with Sub-micrometer Particles via Precipitation Polymerization
Peng Cui, Chang-Tong Song, Xian-Hong Zhang, Dong Chen, Yu-Hong Ma, Wan-Tai Yang
Corrected proof , doi: 10.1007/s10118-019-2252-x
[Abstract](81) [FullText HTML](34) [PDF 851KB](8)
Poly(vinyl chloride), with ultralow molecular weight, produced by free radical polymerization either at high temperature or in the presence of chain transfer agents, is widely used as special resins and polymer process additives. This paper reports a new process, called self-stabilized precipitation polymerization, in which the polymerization of vinyl chloride monomer (VCM) is conducted in hydrocarbon diluents without addition of any suspending agent or emulsifier. The merits of this novel strategy include: (1) PVC resins with ultra-low number-average molecular weight (Mn) from 4000 to 15000, which is much lower than Mn of those prepared by conventional suspension and emulsion polymerizations, (2) sub-micrometer PVC particles with near spherical morphology, and (3) the very simple post-polymerization separation process. Under mild stirring, polymerization proceeds stably and smoothly. The influences of main process factors, such as solvents, initiator and monomer concentrations, polymerization time, and temperature on both particle morphology and Mn of the polymer products are investigated systematically. The molar ratio of ―CH2―CHCl―/―CH=CH―CH2CHCl, a good indicator of structural defects, is about 1000/0.1 which means the low molecular weights do not result from chain transfer to the monomers. Then the mechanism of this polymerization is proposed. In summary, this novel polymerization technology provides a straightforward method for preparing PVC particulate products with low Mn.
Ultrafast Form II to I Transition of Isotactic Polybutene-1
Xing Qiu, Umair Azhar, Jing-Qing Li, Ding-Hai Huang, Shi-Chun Jiang
In press , doi: 10.1007/s10118-019-2273-5
[Abstract](19) [FullText HTML](5) [PDF 467KB](8)
Isotactic polybutene-1 (iPB-1) is a semi-crystalline polymer with polymorph and puzzled structural transitions. The stable form I of iPB-1 with excellent physical and mechanical properties can hardly be obtained directly from the melt, instead metastable form II which would spontaneously and slowly transform into form I. Bypassing the unstable form II formation is of great significance during polymer processing and leads to seeking different research pathways for direct form I formation. Methods for accelerating form II to I transition are another main focus in terms of practical approach for directly obtaining form I. Taking advantage of solvent, an ultrafast transition of iPB-1 from form II to I within minutes has been achieved at room temperature. Such an ultrafast transition is detected after treating with dichloromethane (DCM) at 30 °C, though the framework of isothermally crystalized iPB-1 spherulite morphology could not be fully modified. The ultrafast II-I transition mechanism of iPB-1 is attributed to the solvent-induced packed-mesophase and temperature selected chain conformation adjustment.This ultrafast transition would shed light on the understanding of the mechanisms of polymorphic transitions in iPB-1.
The Effect of Reaction Conditions on the Synthesis of Thermoplastic Elastomers Containing Polyalloocimene, Polyisobutylene and Tapered Blocks
Jozsef Kantor, Judit E Puskas, Gabor Kaszas
In press , doi: 10.1007/s10118-019-2254-8
[Abstract](10) [FullText HTML](11) [PDF 749KB](3)
This work investigates the effect of reaction conditions on the copolymerization of isobutylene (IB) with alloocimene (Allo) in methyl chloride (MeCl) using AlCl3 and ethylaluminum dichloride (EtAlCl2) as coinitiators and adventitious moisture as the initiator. Both AlCl3 and EtAlCl2 produced high molecular weight (Mn > 1.0 × 105 g/mol) thermoplastic elastomers (TPEs) with good mechanical properties in short reaction time (< 10 min). These unique TPEs have unsaturations in the end blocks, leading to easy functionalization and/or crosslinking.
Fabrication of 6FDA-HFBAPP Polyimide Asymmetric Hollow Fiber Membranes and Their CO2/CH4 Separation Properties
Cong-Jun Gan, Xiao-Chen Xu, Xue-Wei Jiang, Feng Gan, Jie Dong, Xin Zhao, Qing-Hua Zhang
In press , doi: 10.1007/s10118-019-2255-7
[Abstract](52) [FullText HTML](32) [PDF 1212KB](6)
In this work, poly(amide acid) solution, the precursor of polyimide, was synthesized by the reaction of 4,4′-(hexafluoroisopropylidene)diphthalicanhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropanane in the solvent of N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF). Then, hollow fiber membranes for high flux gas separation were prepared by dry-jet wet spinning using the precursor solution of poly(amide acid) as the spinning dope and a subsequent imidization process. Silicone rubber was further coated outside the obtained hollow fiber membranes to repair the defects on the denser layer. The effects of internal, external coagulation bath ratios with air gap, and coating solution concentrations on the morphologies, structures, and separation performance of the membranes were studied. Results showed that the sponge-like support layer was formed when the content of NMP was increased from 50% to 90% in the internal coagulation bath. The outer surface of the membrane became denser when the water content in the external coagulation bath increased from 40% to 100%, and the separation coefficient of CO2/CH4 increased by 2 times. This value could reach up to 1.4 when the air gap was 6 cm. With tuning the mass fraction of silicone rubber as 5%, hollow fiber composite membranes with uniform coating layer and an improved separation coefficient of 5.4 could be obtained.
Synthesis of Cerium-containing Polymethylphenyl Silicone and Its Antioxidant Effect on Fluorosilicone Rubber
Yong Guan, Jian Hu, Yong-Kang Huang, Yang You, Huan-Yao Zhang, An-Na Zheng, Xiang Xu, Da-Fu Wei
In press , doi: 10.1007/s10118-019-2266-4
[Abstract](19) [FullText HTML](6) [PDF 724KB](2)
As an essential elastomer used in edge technologies, fluorosilicone rubber (FSR) suffered serious oxidative ageing problem when serving at high temperature. Cerium oxide was generally used as antioxidant additive but still unsatisfied. In order to obtain better antioxidant effect on improving the thermal stability of FSR, a kind of cerium-containing polymethylphenyl silicone (PSI-Ce) was synthesized and the structure was verified by Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR). Due to the homogeneous dispersion on molecular scale, PSI-Ce performed much better antioxidant effect than the commercial CeO2 did, no matter from isothermal degradation at 320 °C or thermal-oxidative ageing test at 230 °C. In particular, after ageing for 72 h, FSR/PSI-Ce (2 phr) maintained 82% of tensile strength and 63% of elongation at break, corresponding to 48% and 42% for FSR/CeO2 (2 phr). Moreover, 2 phr PSI-Ce was equivalent to 0.046 phr CeO2 according to cerium element conservation.
Analysis of Dimer Impurity in Polyamidoamine Dendrimer Solutions by Small-angle Neutron Scattering
Tian-Fu Li, Yi-Yun Cheng, Yu Wang, Hui Wang, Dong-Feng Chen, Yun-Tao Liu, Li Zhang, Wen-Ze Han, Rong-Deng Liu, Zi-Jun Wang, Chun-Ming Yang, Charl J. Jafta, Daniel Clemens, Uwe Keiderling
In press , doi: 10.1007/s10118-019-2260-x
[Abstract](44) [FullText HTML](13) [PDF 573KB](4)
Dimer impurity in the solution of a generation five (G5) polyamidoamine (PAMAM) dendrimer has been investigated by small-angle neutron scattering (SANS). The existence of dimer impurity in dendrimer solution was evidenced by indirect Fourier transform (IFT) analysis of the SANS data, in which the maximum dimension of particles in solution was found to be about twice the diameter of G5 dendrimer. We then developed an analytical model which accounts for the scattering contribution from both dendrimer monomer and dimer. The experimental data were well fitted by using the established model. The results showed that the amount of dimer impurities is significant for the measured three batches of G5 PAMAM dendrimers.
Optimization of Ethylene Glycol Doped PEDOT:PSS Transparent Electrodes for Flexible Organic Solar Cells by Drop-coating Method
Hui-Qin Cui, Rui-Xiang Peng, Wei Song, Jian-Feng Zhang, Jia-Ming Huang, Li-Qiang Zhu, Zi-Yi Ge
In press , doi: 10.1007/s10118-019-2257-5
[Abstract](51) [FullText HTML](19) [PDF 678KB](9)
Fabrication of flexible transparent electrodes (FTEs) is one of the core technologies in the field of flexible electronics. Among multiple choices of FTEs, poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonic acid) (PEDOT:PSS) has shown its promising application in roll-to-roll manufacturing. A simple yet effective method for substantially boosting the conductivity of these conducting polymer films without causing large-domain aggregations is by adding ethylene glycol (EG) as dopant. Herein, we investigated in detail the effects of the secondary solvent of ethylene glycol (EG) on the optical and electrical characteristics of PEDOT:PSS films. The modified PEDOT:PSS FTEs were deposited using drop-coating techniques as it had greater compatibility for large-area samples than the conventional spin-coating method did. The 6% EG-doped PEDOT:PSS FTE via drop-coating method achieved a high figure of merit (FoM) value of 47.24 and the devices fabricated using the optimal PEDOT:PSS FTE yielded a high power conversion efficiency (PCE) of 8.89%, mostly attributed to the modified PEDOT:PSS films that had excellent optical and electrical characteristics with low surface roughness. These results suggested that EG-doping could effectively boost the conductivity of PEDOT:PSS films and that the modified PEDOT:PSS FTE is suitable for roll-to-roll manufacturing in the future.
Synthesis and Physico-chemical Properties of (Co)polymers of 2-[(2E)-1-methyl-2-buten-1-yl]aniline and Aniline
A. Andrianova, A. Shigapova, Y. Biglova, R. Salikhov, I. Abdrakhmanov, A. Mustafin
In press , doi: 10.1007/s10118-019-2261-9
[Abstract](22) [FullText HTML](12) [PDF 910KB](13)
A new soluble polymer on 2-[(2E)-1-methyl-2-buten-1-yl]aniline and its copolymers with aniline basis has been synthesized in various molar ratios. For all samples, the electrical conductivity, morphology, solubility, electrochemical properties, spectral and molecular mass characteristics have been studied, and a comparative analysis with polyaniline was carried out. The substituent introduction into the aniline aromatic ring significantly improves the solubility in typical organic solvents of a high molecular weight product. The morphology of the test compounds depends on the co-monomers ratio. As the content of the substituted aniline in the initial mixture increases, the morphology of the polymer changes from the inherent polyani`line fibrous microstructure to the globular one with irregular substituted polyaniline shapes and sizes. Electrochemical study of the samples revealed that the higher oxidation potential is, the wider the band gap, ranging from 2.00 to 2.15. The electrical conductivity decreases in proportion to the increase in the substituted aniline concentration of the initial co-monomer mixture and amounts to 12.5 ÷ 35.7 × 106 nSm.
Crystallization and Phase Behavior in Block Copolymer Solution: An in Situ Small Angle X-ray Scattering Study
Hong-Yan Zhu, Feng Tian, Xiu-Hong Li, Hui-Bin Qiu, Jie Wang
In press , doi: 10.1007/s10118-018-2258-4
[Abstract](55) [FullText HTML](23) [PDF 1019KB](23)
Amphiphilic diblock copolymers self-assemble into a variety of micellar structures with diverse shapes in selective solvents. Here, we study the concentration and temperature dependence of the packing structure of spherical micelles of a polyisoprene-b-poly(2-vinylpyridine) (PI-b-P2VP) diblock copolymer in toluene using synchrotron radiation small angle X-ray scattering (SR-SAXS) and atomic force microscopy (AFM) techniques. Randomly packed spherical micelles are detected in dilute solution, while in concentrated solutions, face-centered cubic (FCC), body-centered cubic (BCC) mixed crystal structures, and pure BCC crystal structures are observed with an increase in concentration. In situ SAXS experiments on the FCC/BCC mixed crystal structures reveal a novel FCC/BCC → BCC → Disorder → BCC phase behavior during the temperature annealing process. The results demonstrated that the BCC phase is apparently more stable than the FCC phase in the current sphere-packing system and FCC/BCC is a metastable state. The incompatibility of PI and P2VP blocks decreases at a higher temperature and renders the variation of domain spacing.
Increase the Content of β Phase of Poly(9,9-dioctylfluorene) by Synergistically Controlling Solution Aggregation and Extending Film-forming Time
Ya-Di Liu, Qiang Zhang, Xin-Hong Yu, Jian-Gang Liu, Yan-Chun Han
In press , doi: 10.1007/s10118-019-2259-3
[Abstract](63) [FullText HTML](32) [PDF 772KB](14)
In poly(9,9-dioctylfluorene) (PFO), β phase (coplanar conformation with the intra-chain torsion angle of 165°) has greater conjugation length and higher degree of order compared to those of α phase, which favors charge carrier transport. However, the highest content of β phase obtained so far is 45%. We propose to increase the content of β phase by promoting the solution aggregation of PFO molecules and extending film-forming time. For this purpose, 1,8-diiodooctane (DIO) is added to PFO o-xylene solution, which enhances the interaction of PFO chains and improves the planarity of PFO backbone, resulting in the formation of ordered aggregation. The aggregates act as nucleation centers to promote the formation of β phase. The content of β phase increases with increasing DIO concentration and reaches a platform of 39% as DIO is more than 4 vol%. Furthermore, the film is kept in a sealed environment with o-xylene atmosphere for 3 h, thus the PFO molecules have enough time to diffuse to the crystallization front and achieve disorder-order transition. As a result, the crystallinity of PFO is improved significantly and the content of β phase increases to 52%, reaching the highest value reported so far.
Controllable Emission via Tuning the Size of Fluorescent Nano-probes Formed by Polymeric Amphiphiles
Xiao-Cheng Wang, Shi-Xin Zhou, Lan Ding, Yu-Han Zhao, Shen-Xi Min, Bin Dong, Bo Song
In press , doi: 10.1007/s10118-019-2256-6
[Abstract](46) [FullText HTML](28) [PDF 783KB](12)
Incorporating fluorophores into polymeric nanoparticles has been testified as a feasible way to improve the emitting property and bio-compatibility of nano-emitters, which can be applied as fluorescent probes in labeling cells for imaging. Plenty of efforts have been made on the above direction. However, the size effect of nano-emitters has not been addressed yet mainly given the difficulties in controlling morphology and size of the assemblies. In our preceding study, we employed post-polymerization modification method for preparing amphiphilic copolymers, and obtained core-shell (the hydrophobic fluorophores are wrapped inside the nanoparticle to form the core) assemblies in aqueous solution. By this method, we are able to regulate the ratio of the hydrophilic/hydrophobic moieties, and thus alternate the size of the assemblies in a rather simple way. In this study, we synthesized a series of random copolymers by changing the ratio of poly(ethylene glycol) to tetraphenylethylene groups. Notably, the number of repeating units of the polymer was controlled constant for all the copolymers. The self-assembly of these copolymers resulted in different sizes of nanoparticles, and the size decreased with the decreasing fraction of poly(ethylene glycol). Interestingly, the emission of the nanoparticles showed size dependence, and smaller diameter corresponded to stronger emission. Being cultured with HeLa cells, either the large (diameter of ~300 nm) or the small (diameter of ~180 nm) nano-emitters allowed for very high cell viabilities up to 25 μg·mL−1. Both of them can be applied in cell imaging and provide high contrast fluorescent images.
Using an Inhibitor to Prevent Plasticizer Migration from Polyurethane Matrix to EPDM Based Substrate
Hadi Rezaei-Vahidian, Tohid Farajpour, Mahdi Abdollahi
In press , doi: 10.1007/s10118-019-2251-y
[Abstract](46) [FullText HTML](21) [PDF 671KB](0)
The loss of adhesion between the propellant and insulator is one of the most important problems in solid propellant motors due to migration of plasticizer to interface of propellant and insulator. In this work, the polyurethane (PU) binder containing DOP plasticizer was used as a polymeric matrix and β-cyclodextrin (β-CD) was applied as inhibitor agent to prevent plasticizer migration from the PU matrix into the ethylene propylene diene monomer (EPDM) substrate. To increase the compatibility of β-CD and PU matrix, a derivative of β-CD has been synthesized using toluene di-isocyanate (β-CD-TDI). The synthesized derivative was characterized by MALDI-MS and FTIR-ATR analyses. FTIR-ATR results confirmed the formation of bonding between β-CD and the polymeric network while the MALDI-MS results showed that the synthesized derivative contained two β-CD and 7 TDI molecules bonded to β-CD. Investigation of the mechanical properties of PU modified by β-CD-TDI showed a decrease in tensile strength and an increase in elongation at break with increasing β-CD-TDI content. DMTA results showed a decrement in crosslinking density by increasing the β-CD-TDI content. Also, to investigate plasticizer migration, extraction of the DOP plasticizer from samples was performed using dichloromethane solvent and its concentration was measured by gas chromatography. The results of migration evaluation after four months showed that using β-CD as an inhibitor agent in the PU binder could prevent the migration of plasticizer to EPDM substrate.
Graphene Fibers: Advancing Applications in Sensor, Energy Storage and Conversion
Guan-Hang Yu, Qing Han, Liang-Ti Qu
Corrected proof , doi: 10.1007/s10118-019-2245-9
[Abstract](75) [FullText HTML](25) [PDF 1456KB](20)
Graphene fibers are a kind of novel carbon fibers assembled by orderly aligned graphene sheets with high flexibility, good conductivity, high thermal conductivity, and low density, which make them possible to be widely used in high-performance and multi-functional compound materials as well as flexible electronic devices. In this review, we summarize the research progress in the synthesis of graphene fibers, and their applications in sensor, energy storage, and energy conversion. Furthermore, the current issues and some prospects for the future trend of graphene fibers are discussed.
Synthesis of a Rod-rod Diblock Copolymer, Poly(3-hexylthiophene)-block-poly(furfuryl isocyanate), through the Anionic Polymerization with an Oxyanionic Macroinitiator
Chang-Geun Chae, Joonkeun Min, In-Gyu Bak, Jae-Suk Lee
Corrected proof , doi: 10.1007/s10118-019-2243-y
[Abstract](71) [FullText HTML](44) [PDF 961KB](7)
A rod-rod diblock copolymer (diBCP), poly(3-hexylthiophene)-block-poly(furfuryl isocyanate) (P3HT-b-PFIC), was synthesized through the anionic polymerization with an oxyanionic macroinitiator of P3HT. The properties of the diBCP (molecular weight, dispersity, composition, thermal stability, UV-visible absorption, and thin film morphology) were determined by various analytical methods. P3HT-b-PFIC was blended with C60 in a toluene solution to prepare a thin film of binary electron donor/acceptor system. Such blending enabled partial conjugation of the two components by the Diels-Alder reaction between furan and C60 at 60 °C for 3 h; the mixture was then spin-cast as a thin film, and annealed at 250 °C for 24 h. Tapping-mode atomic force microscopy (AFM) revealed that P3HT and C60 domains had nanoscale interfaces without a large phase segregation. This result indicated that the microphase separation of C60-functionalized P3HT-b-PFIC preserved even at high temperature provided free C60 molecules with channels to diffuse on the sides of P3HT domain, thus preventing the macroscopic crystallization of free C60 through the interfacial stabilization.
Facile Synthesis of Functional Poly(ε-caprolactone) via Janus Polymerization
Huan Qiu, Zhe-Ning Yang, Jun Ling
Corrected proof , doi: 10.1007/s10118-019-2242-z
[Abstract](71) [FullText HTML](36) [PDF 1227KB](15)
Functionalized aliphatic polyesters attract increasing attentions as biocompatible and biodegradable polymers with broad applications in biological science. In this contribution, we propose a facile and controllable synthetic technique for functional poly(ε-caprolactone) (PCL) via Janus polymerization, which comprises cationic ring-opening copolymerization (ROP) of ε-caprolactone (CL) with 3,3-bis(chloromethyl) oxacyclobutane (CO) and (coordinated) anionic ROP of CL at a single propagating chain by rare earth metal triflates (RE(OTf)3) and propylene oxide, thus generating block copolymers in one step. The compositions of the copolymers of poly(CL-b-(CL-r-CO)) can be modulated by various RE(OTf)3. Scandium triflate catalyzes Janus polymerization to yield the copolymers containing the highest CO contents among all the RE(OTf)3 catalysts used with complete conversion of CL. The chlorine in CO repeating units is ready to be transferred into azide group which affords the modification sites to react with 9-ethynyl-9-fluorenol and mPEG-alkyne, respectively, via copper(I)-catalyzed azide-alkyne cycloaddition reaction with quantitative conversions of azides, as confirmed by FTIR analyses. According to NMR and SEC analyses, copolymers (PCC-g-PEG) bearing a homo-PCL block and a PEG-grafted block of poly(CO-co-CL) demonstrate well-defined chemical structures. The investigations on thermal properties reveal the strong phase separation between PCL and PEG blocks. The amphiphilic PCC-g-PEG is able to self-assemble into micelles in aqueous solution while cylindrical and lamellar morphologies are observed in bulk. We provide an efficient protocol to synthesize functional PCL combining one-step Janus polymerization and precise post-polymerization click reaction.
Superhydrophobic PVDF/TiO2-SiO2 Membrane with Hierarchical Roughness in Membrane Distillation for Water Recovery from Phenolic Rich Solution Containing Surfactant
N. Hamzah, C. P. Leo, B. S. Ooi
Corrected proof , doi: 10.1007/s10118-019-2235-y
[Abstract](80) [FullText HTML](34) [PDF 1256KB](4)
Superhydrophobic poly(vinylidene fluoride) (PVDF) membrane incorporated with nanoparticles was applied in membrane distillation to recover water from phenolic rich solution containing surfactant. The membranes coated on woven support were fabricated using phase inversion with dual bath coagulation and post-modified using silane. The membranes incorporated with TiO2, SiO2, or a mixture of TiO2-SiO2 nanoparticles achieved the water contact angle higher than 160°. The addition of TiO2-SiO2 mixture into PVDF matrix further enhanced the hierarchical roughness of membrane. Hence, PVDF/TiO2-SiO2 membrane achieved the highest permeation flux and rejected 99.9% of gallic acid in the feed (100 g/L). PVDF/TiO2-SiO2 membrane also maintained a relative flux (J/J0) higher than 0.9 after 8 h of operation. Even with the presence of surfactant in phenolic rich solution, PVDF/TiO2-SiO2 membrane was able to exhibit relative flux above 0.8. The significant changes on the hydrophobicity and chemical properties of PVDF/TiO2-SiO2 membrane due to fouling were not observed after 50 h of static adsorption test.
Evolution of Conformation and Dynamics of Solvents in Hydration Shell along the Urea-induced Unfolding of Ubiquitin
Ke-Cheng Yang, Feng-Chao Cui, Ce Shi, Wen-Duo Chen, Yun-Qi Li
Corrected proof , doi: 10.1007/s10118-019-2238-8
[Abstract](69) [FullText HTML](41) [PDF 968KB](14)
A clear diagram for the unfolding of protein induced by denaturant is a classical but still unsolved challenge. To explore the unfolded conformations of ubiquitin under different urea concentrations, we performed hybrid Monte Carlo-molecular dynamics simulations (MC-MD) guided by small angle X-ray scattering (SAXS) structural information. Conformational ensembles sampled by the hybrid MC-MD algorithm exhibited typical 3D structures at different urea concentrations. These typical structures suggested that ubiquitin was subjected to a sequential unfolding, where the native contacts between adjacent β-sheets at first were disrupted together with the exposure of hydrophobic core, followed by the conversion of remaining β-strands and helices into random coils. Ubiquitin in 8 mol·L−1 urea is almost a random coil. With the disruption of native structure, urea molecules are enriched at protein hydrated layer to stabilize newly exposed residues. Compared with water, urea molecules prefer to form hydrogen bonds with the backbone of ubiquitin, thus occupying nodes of the hydrogen bonding network that construct the secondary structure of proteins. Meanwhile, we also found that the slow dynamics of urea molecules was almost unchanged while the dynamics of water was accelerated in the hydration shell when more residues were unfolded and exposed. The former was also responsible for the stabilization of unfolded structures.
Diffusion Mode Transition between Gaussian and Non-Gaussian of Nanoparticles in Polymer Solutions
Yi Ye, Han Qin, Ming Tian, Jian-Guo Mi
Corrected proof , doi: 10.1007/s10118-019-2237-9
[Abstract](70) [FullText HTML](38) [PDF 1204KB](2)
The dynamic density functional theory is applied to study the diffusion of nanoparticles in polymer solutions, in which different diffusion modes have been identified by exploiting the density and free energy evolutions. Under the condition of low polymer concentration, diffusion is controlled by particle free motion with a normal Gaussian type. As the concentration increases, the non-Gaussian behavior can be observed when the particle size is comparable to the correlation length of polymer chain. Particles need to penetrate through a cage and overcome an entropic barrier, where the hopping and the model-coupling diffusion coexist. Further increase of polymer concentration can result in complete restriction of the particle by surrounding polymer segments. In this case, the non-Gaussian process fades away, and particle diffusion is controlled by Rouse dynamics of polymer chains with the generalized Gaussian characteristics.
Controlled Polymerization of Methyl Methacrylate and Styrene via Cu(0)-Mediated RDRP by Selecting the Optimal Reaction Conditions
Yong-Peng Miao, Jing Lyu, Hai-Yang Yong, Sigen A, Yong-Sheng Gao, Wen-Xin Wang
Corrected proof , doi: 10.1007/s10118-019-2236-x
[Abstract](60) [FullText HTML](26) [PDF 397KB](4)
Cu(0)-mediated reversible deactivation radical polymerization (Cu(0)-mediated RDRP) has been demonstrated as an excellent technique to control the polymerization of multiple vinyl monomers (e.g., acrylates, methacrylates, and styrene). However, the complexity of the reaction mechanism and multi-component system nature make it challenging to choose the appropriate conditions and consider the factors of achieving controllable polymerization when switching from one monomer to others with different reactivities. Herein, by polymerizing two examplary monomers: methyl methacrylate (MMA) and styrene via Cu(0)-mediated RDRP under different conditions, we have found that the reaction parameters (e.g., initiator, ligand, solvent, and deactivator) play a crucial role in regulating two equilibriums: (i) mutual conversion of different copper species which determines the relative concentration of Cu(I) and Cu(II), and (ii) polymerization equilibrium which is the combination of activation/deactivation, propagation and termination processes. We have demonstrated that by taking both the mutual conversion of different copper species and the polymerization equilibrium into account, the optimal reaction conditions could be selected, and the well-controlled Cu(0)-mediated RDRPs of methyl methacrylate and styrene were achieved with narrow molecular weight distributions and predicted molecular weight.
Electrospun Poly(p-dioxanone)/Poly(ester-urethane)ureas Composite Nanofibers for Potential Heart Valve Tissue Reconstruction
Juan Du, Ji-Hu Wang, Hai-Yan Yu, Yan-Yan Zhang, Li-Hui Pu, Jin-Cheng Wang, Shu-Yang Lu, Si-Hao Chen, Tong-He Zhu
Corrected proof , doi: 10.1007/s10118-019-2231-2
[Abstract](94) [FullText HTML](60) [PDF 1653KB](13)
Electrospun nanofibrous mats represent a new generation of medical textiles with promising applications in heart valve tissue reconstruction. It is important for biomaterials to mimic the biological and mechanical microenvironment of native extracellular matrix (ECM). However, the major challenges are still remaining for current biomedical materials, including appropriate mechanical properties, biocompatibility, and hemocompatibility. In the present work, the novel composite nanofibrous mats of poly(p-dioxanone) (PDO) and poly(ester-urethane)ureas (PEUU) are fabricated by electrospinning system. The optimal combination ratio of PDO to PEUU may balance the mechanical properties and cellular compatibility to match the newly formed tissue. In PDO/PEUU composite nanofibrous mats, PEUU can provide the biomimetic elastomeric behavior, and PDO could endow the excellent biocompatibility. In comparison to nanofibrous mat of neat PDO, the composite showed significantly improved mechanical properties, with 5-fold higher initial elongation at break. Furthermore, human umbilical vein endothelial cells (HUVECs) were cultured on the composite to evaluate its ability to rapidly endothelialize as heart valve tissue engineering. The results revealed that PDO/PEUU composite nanofibrous mats could promote cell adhesion and proliferation, especially for the ratio of 60/40. Overall, PDO/PEUU composite nanofibrous mats (60/40) show the excellent mechanical properties, appropriate biocompatibility and hemocompatibility which meet the necessary norm for tissue engineering and may be suitable for potential heart valve tissue reconstruction.
Direct Comparison of Crystal Nucleation Activity of PCL on Patterned Substrates
Jian Hu, Rui Xin, Chun-Yue Hou, Shou-Ke Yan, Ji-Chun Liu
Corrected proof , doi: 10.1007/s10118-019-2226-z
[Abstract](77) [FullText HTML](34) [PDF 1017KB](8)
A sample containing different regions with poly(ε-caprolactone) (PCL), oriented polyethylene (PE), and oriented isotactic polypropylene (iPP) films in contact with glass slide has been prepared to be observed in the same view field in an optical microscope and the crystallization of PCL in different regions during cooling from 80 °C down to room temperature at a rate of 1 °C·min−1 was studied. The results showed that the crystallization of PCL started first at the PE surface and then at the iPP surface, while its bulk crystallization occured much later. This indicates that though both PE and iPP are active in nucleating PCL, the nucleation ability of PE is stronger than that of iPP. This was due to a better lattice matching between PCL and PE than that between PCL and iPP. Moreover, since lattice matching existed between every (hk0) lattice planes of both PCL and PE but only between the (100)PCL and (010)iPP lattice planes, the uniaxial orientation feature of the used PE and iPP films resulted in the existence of much more active nucleation sites of PCL on PE than on iPP. This led to the fact that the nucleation density of PCL at PE surface was so high that the crystallization of PCL at PE surface took place in a way like the film developing process with PCL microcrystallites happened everywhere with crystallization proceeding simultaneously. On the other hand, even though iPP also enhanced the nucleation density of PCL evidently, the crystallization of PCL at iPP surface included still a nucleation and crystal growth processes similar to that of its bulk crystallization.
The Influence of Trans-1,4-poly(butadiene-co-isoprene) Copolymer Rubbers (TBIR) with Different Molecular Weights on the NR/TBIR Blends
Hao Wang, Ri-Guo Wang, Yun-Sheng Ma, Bo Luan, Ai-Hua He
Corrected proof , doi: 10.1007/s10118-019-2229-9
[Abstract](60) [FullText HTML](29) [PDF 866KB](6)
The molecular weight of a polymer is of prime importance and greatly influences the processing and mechanical properties of the polymer. Trans-1,4-poly(butadiene-co-isoprene) multi-block copolymer rubbers (TBIR) exhibit outstanding fatigue resistance, low heat build-up and good abrasion resistance, and are expected to be desirable candidate for high performance tire. Study on the influence of TBIR with different molecular weights on the structure and properties of TBIR and natural rubber (NR)/TBIR blends is essential to understand its contribution to the greatly improved dynamic properties of the rubber vulcanizates. TBIR with different molecular weights characterized by 1H-NMR, 13C-NMR, GPC, and DSC were highly trans-1,4-copolymers with similar chain sequence distribution and crystalline trans-1,4-polyisoprene (TPI) blocks. The green strength and modulus of TBIR increased with the increasing molecular weight. The NR/TBIR compounds filled with 40 phr carbon black were chemically cured by sulfur for the preparation of NR/TBIR vulcanizates. The compatibility between NR and TBIR, filler distribution, crosslinking bond and density, and properties of NR/TBIR vulcanizates were studied. The NR/TBIR vulcanizates showed increasing tensile strength, hardness, modulus, rebound, abrasion resistance, and flexural fatigue properties with increasing molecular weight of TBIR. Furthermore, they presented significant improvement in flexural fatigue resistance when compared with that of NR vulcanizate. The contribution mechanism of TBIR on the NR/TBIR blends was discussed. The TBIR with a wide range of molecular weight are ideal rubbers for high performance tires.
A Phenol-containing α-Diimine Ligand for Nickel- and Palladium-Catalyzed Ethylene Polymerization
Chen Tan, Wen-Min Pang, Chang-Le Chen
Corrected proof , doi: 10.1007/s10118-019-2232-1
[Abstract](140) [FullText HTML](40) [PDF 936KB](31)
A phenol-containing dibenzhydryl-based α-diimine ligand bearing hydroxy group on para-position of aniline moiety was designed, synthesized, and investigated in Ni- and Pd-catalyzed ethylene polymerization. The Ni complex bearing hydroxy groups resulted in not only high polyethylene molecular weight (Mn up to 1.5 × 106), but also significantly increased melting temperature (Tm up to 123 °C) and greatly decreased branching density (33/1000C) versus the Ni catalyst bearing OMe group on para-position of aniline moiety. This is consistent with the hypothesis that the deprotonation of the phenol moiety generated a phenoxide bearing strong electron-donating O substituent by methylaluminoxane (MAO) cocatalyst. The Pd complexes bearing hydroxy groups exhibited similar catalytic properties to those of the Pd catalyst bearing OMe groups did.
Regioselective Polymerizations of α-Olefins with an α-Diamine Nickel Catalyst
Heng Liao, Jie Gao, Liu Zhong, Hai-Yang Gao, Qing Wu
Corrected proof , doi: 10.1007/s10118-019-2227-y
[Abstract](112) [FullText HTML](47) [PDF 717KB](14)
Polymerizations of linear α-olefins (CnH2n, CH2=CH―R, R = Cn−2) catalyzed by early transition metals typically afford amorphous polymers with alkyl chains (Cn−2), while chain-straightening polymerizations of α-olefins with nickel-based catalysts produce semicrystalline polyolefins. Polymerizations of various α-olefins were carried out using an α-diamine nickel catalyst with a significantly distorted chelating ring. The influences of temperature, monomer concentration, and chain length of α-olefins on polyolefin microstructure were examined in detail. The α-diamine nickel catalyst realized highly regioselective 2,1-insertion of α-olefins regardless of reaction temperature and monomer concentration. Increased chain length of α-olefins led to the formation of more linear polyolefin. Semicrystalline polyolefins with high melting temperatures (Tm) were made from α-olefins through highly regioselective 2,1-insertion and precise chain-straightening.
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
Corrected proof , doi: 10.1007/s10118-019-2203-6
[Abstract](334) [FullText HTML](54) [PDF 6630KB](20)
" Thiol-yne” click reaction has already been widely applied 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, thus the in-chain di-addition strategy could endow us with 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 showed 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 obtained efficiently. Further researches investigated that the 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 feedings. 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.
A User-friendly Living Cationic Polymerization: Degenerative Chain-transfer Polymerization of Vinyl Ethers by Simply Using Mixtures of Weak and Superstrong Protonic Acids
Mineto Uchiyama, Masataka Sakaguchi, Kotaro Satoh, Masami Kamigaito
Corrected proof , doi: 10.1007/s10118-019-2233-0
[Abstract](61) [FullText HTML](31) [PDF 729KB](2)
Mixtures of a weak protonic acid and a trace amount of superstrong protonic acid were used for the simple control of the cationic polymerization of vinyl ethers via a degenerative chain-transfer mechanism, in which the former acid works as a precursor of the chain transfer agent (CTA) or the dormant species and the latter works as a source of the cationic propagating species. The addition of mixtures of phosphoric acid dibutyl ester ((n-BuO)2PO2H) or 1-octanethiol (n-C8H17SH) and a trace amount of trifluoromethanesulfonic acid (TfOH) to a solution of isobutyl vinyl ether (IBVE) at −78 °C resulted in polymers with controlled molecular weights, which were basically determined by the feed ratio of IBVE to the weak protonic acid, and narrow molecular weight distributions (Mw/Mn ≈ 1.1). These results were almost the same as those obtained using their prepared adducts of IBVE as CTAs in the presence of a trace amount of TfOH under similar conditions. Methanesulfonic acid (CH3SO3H), whose adduct of IBVE has not been isolated due to instability, was similarly used in conjunction with trace TfOH to result in controlled molecular weights but slightly broader MWDs (Mw/Mn = 1.2–1.8). These results indicate that the sulfoxonium ion is also an effective intermediate in the cationic DT polymerization in addition to the phosphonium and sulfonium intermediates derived from (n-BuO)2PO2H and n-C8H17SH, respectively. The simple living cationic polymerization was thus achieved by using a combination of a weak protonic acid and a trace amount of TfOH, which are both easily available, low cost, free from metal, and easy to handle, without need for preparation of the initiator.
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
Corrected proof , doi: 10.1007/s10118-019-2212-5
[Abstract](102) [FullText HTML](59) [PDF 2177KB](12)
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.
Polymerization Mechanism of Methyl Methacrylate Initiated by Ethyl Acetate/t-BuP4
De-Yong Xia, Qi-Min Jiang, Wen-Yan Huang, Hong-Jun Yang, Xiao-Qiang Xue, Li Jiang, Bi-Biao Jiang
Corrected proof , doi: 10.1007/s10118-019-2228-x
[Abstract](78) [FullText HTML](63) [PDF 668KB](7)
The anionic polymerization of methyl methacrylate (MMA) was carried out using phosphazene base t-BuP4 and ethyl acetate (EA) as the catalyst and the initiator, respectively. Gas chromatography (GC), size exclusion chromatography (SEC) measurements, and nuclear magnetic resonance (NMR) analyses were used to reveal the polymerization mechanism and to confirm the polymer structure. The results confirmed the proposed polymerization mechanism and the polymer structure, while the initiator efficiency was low. Meanwhile, the initiation by methoxy anion coming from hydrolysis of the ester bond in MMA was also observed. As a result, there is a marked deviation between the theoretical molecular weight and the measured molecular weight, and it is essential to carry out the polymerization at excessive dosage of t-BuP4 for preparing polymers with narrow molecular weight distribution.
Kinetic Monte Carlo Simulations of Polymer Cold Crystallization
Cheng-Huan Xu, Ji-Ping Wang, Wen-Bing Hu
Corrected proof , doi: 10.1007/s10118-019-2222-3
[Abstract](68) [FullText HTML](43) [PDF 671KB](5)
We performed kinetic Monte Carlo simulations of a lattice polymer model holding intramolecular and intermolecular activation barriers for polymer diffusion, on the basis of the previous dynamic Monte Carlo simulations of polymer crystallization. We explored the effective parameter sets for two barriers to freeze the amorphous polymers at low temperatures. The subsequent heating process of the frozen amorphous polymers exhibits clear cold crystallization behaviors. We made preliminary investigation on the crystallinity and the morphology of polymer crystallites yielded during the cold crystallization, which appear in consistence with our common experimental observations. Our present work paves the way for molecular simulations of hot and cold polymer crystallization in the whole temperature range between the glass transition temperature and the melting temperature.
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
Corrected proof , doi: 10.1007/s10118-019-2209-0
[Abstract](91) [FullText HTML](49) [PDF 651KB](4)
Salt metathesis reactions between pyridyl-methylene-cyclopentadienyl lithium salt and LnCl3 followed by the 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, which were 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).
Langmuir-Blodgett Films of C60-end-capped Poly(ethylene oxide)
Ke Ou, Xian Xu, Yu Shao, Wei-Jie Wang, Wen-Bin Zhang, Shu-Guang Yang
Corrected proof , doi: 10.1007/s10118-019-2234-z
[Abstract](62) [FullText HTML](30) [PDF 503KB](3)
Buckyballs (C60) are linked to one end and two ends of linear poly(ethylene oxide) (PEO) chains through highly efficient click chemistry to obtain giant amphiphilic molecules C60-PEO and C60-PEO-C60, respectively. C60-PEO and C60-PEO-C60 molecules are spread on water surface and then transferred to solid substrates with Langmuir-Blodgett (LB) film deposition approach. C60-PEO and C60-PEO-C60 exhibit fractal growth behavior on the solid substrate under certain conditions owing to the crystallization ability of PEO segment. PEO chain length and the end capped mode both affect the fractal growth pattern.
Isothermal Crystallization of iPP in Environment-friendly Diluents: Effect of Binary Diluents and Crystallization Temperature on Crystallization Kinetics
Yu-Jie Wang, Su-Ying Yan, Zhi-Ping Zhao, Zhen-Yu Xi
Corrected proof , doi: 10.1007/s10118-019-2219-y
[Abstract](70) [FullText HTML](59) [PDF 1025KB](6)
The growing demand for non-toxic solvents for membrane preparation has motivated the studies for green and sustainable alternatives of solvents. The effect of droplet isothermal growth within the liquid-liquid phase separation region on isothermal spherulitic growth rate of isotactic polypropylene (iPP) was investigated. The results showed that the droplets grew up at a rate of 0.0172 μm·s−1. The larger droplets slowed down the isothermal spherulitic growth rate of iPP. Higher mass ratio of carnauba wax (Cwax)/soybean oil (SO) resulted in faster droplet growth due to weak interaction with polymers. The isothermal crystallization behaviors of iPP in environment-friendly binary diluents consisting of Cwax and SO mixture were further investigated experimentally using polarized optical microscopy. It was demonstrated that the isothermal spherulitic growth rate of iPP in diluents decreased nonlinearly with the increasing crystallization temperature. Compared with virgin iPP, isothermal spherulitic growth rate of iPP in SO diluent was significantly slowed down. The spherulitic growth was further retarded after the addition of Cwax in mixed diluents, resulting in a lower crystallization rate than that in SO. Moreover, the crystal form of iPP membranes was found to be α type through the characterization of small angle X-ray scattering and wide angle X-ray diffraction.
Ethylene-bridged Indenyl-fluorenyl Metallocene Complexes for Efficient Preparation of Allyl-terminated Propylene Oligomers and Polymers via Selective β-Methyl Transfer
Lei Zhang, Bin Zhang, Haiyan Ma
Corrected proof , doi: 10.1007/s10118-019-2224-1
[Abstract](150) [FullText HTML](58) [PDF 1036KB](12)
Four C1-symmetric ansa-metallocene complexes, C2H4(Ind)(2,7-tBu2-Flu)ZrCl2 (4), C2H4(3-Bn-Ind)(2,7-tBu2-Flu)ZrCl2 (5), C2H4(3-Bn-Ind)(3,6-tBu2-Flu)ZrCl2 (6), and C2H4(3-Bn-Ind)(2,7-tBu2-Flu)HfCl2 (7), were synthesized and characterized. The structures of complexes 4, 5, and 7 were further determined via X-ray diffraction studies. Upon activation with modified methylaluminoxane (MMAO) or AliBu3/[Ph3C][B(C6F5)4] (TIBA/TrB), most of these complexes showed high efficiency in catalyzing propylene oligomerization/polymerization to afford products dominantly with allyl terminals via selective β-methyl transfer (β-Me transfer). The introduction of 3-benzyl group on the indenyl ring of the complexes was found to be crucial in enabling highly selective β-Me transfer during the polymerization process, leading to selectivities up to 89% obtained by zirconocene complexes 5 and 6, and up to 91% obtained by hafnocene complex 7. Detailed chain-end analysis by 1H-NMR, 13C-NMR, and MALDI-TOF mass spectroscopy revealed that the allyl chain-ends of the polymeric products resulted from a selective β-Me transfer process after two successively primary insertions of the monomer. Further studies concerning the dependence of chain release selectivity as well as the molecular weight of products on monomer concentration suggested that both β-Me transfer (major) and β-hydrogen transfer (β-H transfer) (minor) mediated by 5/MMAO and 6/MMAO systems may mainly operate in a bimolecular pathway.
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
Corrected proof , doi: 10.1007/s10118-019-2211-6
[Abstract](171) [FullText HTML](51) [PDF 2379KB](4)
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 synthesizedvia 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 was 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.
Positron Spectroscopy of Free Volume in Poly(vinylidene fluoride) after Helium Ions Irradiation
Jin-Zhe Lyu, Roman Laptev, Natalya Dubrova
Corrected proof , doi: 10.1007/s10118-019-2195-2
[Abstract](129) [FullText HTML](76) [PDF 608KB](6)
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
Corrected proof , doi: 10.1007/s10118-019-2194-3
[Abstract](117) [FullText HTML](105) [PDF 871KB](6)
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.
Electrically Conductive and Flame Retardant Graphene/Brominated Polystyrene/Maleic Anhydride Grafted High Density Polyethylene Nanocomposites with Satisfactory Mechanical Properties
Yu Chen, Jian Yao, Ming-Ke Xu, Zhi-Guo Jiang, Hao-Bin Zhang
Corrected proof , doi: 10.1007/s10118-019-2220-5
[Abstract](89) [FullText HTML](57) [PDF 852KB](4)
Electrically conductive and flame-retardant maleic anhydride grafted high-density polyethylene (MA-HDPE) nanocomposites with satisfactory mechanical properties are fabricated by melt compounding MA-HDPE with polyethyleneimine (PEI)-modified reduced graphene oxide (PEI@RGO) as the conductive nanofiller and brominated polystyrene (BPS) as the flame retardant. The modification with PEI significantly improves the interfacial compatibility and dispersion of the RGO sheets in the MA-HDPE matrix, leading to electrically conductive nanocomposites with enhanced mechanical properties. Furthermore, the addition of 25 wt% of BPS makes the nanocomposite flame-retardant with a UL-94 V-0 rating. Thus, the multifunctional RGO/MA-HDPE nanocomposites with good electrical, flame-retardant, and mechanical properties would have potential applications in construction and pipeline fields.
Synthesis of Eugenol Bio-based Reactive Epoxy Diluent and Study on the Curing Kinetics and Properties of the Epoxy Resin System
Bin Chen, Feng Wang, Jing-Yu Li, Jia-Lu Zhang, Yan Zhang, Hai-Chao Zhao
Corrected proof , doi: 10.1007/s10118-019-2210-7
[Abstract](114) [FullText HTML](51) [PDF 1053KB](11)
In this study, monoglycidyl silyl etherated eugenol (GSE) was synthesized as reactive epoxy diluent, and the chemical structure of GSE, intermediates, and products were characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H-NMR). GSE existed as a potential bio-based reactive diluent for petroleum-based epoxy resin. The curing kinetics of EP/HHPA/GSE system was studied by non-isothermal DSC method. The kinetics parameters were calculated by using the Kissinger model, Crane model, Ozawa model, and β-T (temperature-heating rate) extrapolation, respectively. In addition, the effects of GSE on the thermo-mechanical properties and thermal stability of EP/HHPA/GSE systems were studied, indicating that GSE can effectively improve the toughness and thermal decomposition temperature of the epoxy system.
Photoresponsive Supramolecular Hydrogel Co-assembled from Fmoc-Phe-OH and 4,4′-Azopyridine for Controllable Dye Release
Xiao-Qiu Dou, Chang-Li Zhao, Nabila Mehwish, Ping Li, Chuan-Liang Feng, Holger Schönherr
Corrected proof , doi: 10.1007/s10118-019-2223-2
[Abstract](104) [FullText HTML](46) [PDF 1017KB](15)
Photoresponsive hydrogels have been attractive because they can provide precise spatial and temporal control for molecule release, whereas the conventional preparation of photoresponsive hydrogels generally involves complex chemical synthesis steps or specific conditions which limits their practical applications. Herein, a new photoresponsive hydrogel is facilely prepared via co-assembly of two simple molecules, Fmoc-Phe-OH and Azp, without chemical synthesis. The co-assembly mechanism, morphology, and photoresponsiveness of (Fmoc-Phe-OH)-Azp hydrogel are investigated by circular dichroism (CD), ultraviolet-visible (UV-Vis), fluorescence, 1H nuclear magnetic resonance (1H-NMR), attenuated total internal reflection Fourier transform Infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy (SEM). Furthermore, the enhanced release of encapsulated sulforhodamine B (SRB) dye molecules can be achieved via UV light irradiation. The enhanced dye release amount can be controlled by manipulating photoirradiation time. This study provides a facile way to prepare photoresponsive hydrogel which holds great potential for controllable drug release.
A Theoretical Study on Transitional Shear Flow Behavior of the Compressible and Isothermal Thermoplastic Polymer
Dong-Lei Liu, Feng Zhou, Kun Fang
Corrected proof , doi: 10.1007/s10118-019-2214-3
[Abstract](98) [FullText HTML](59) [PDF 498KB](26)
By extending the virtual conformational element of the polymer chain, a dynamic end-to-end (ETE) vector was presented to describe the chain’s instantaneous morphology based on the spring-bead theory. A feasible viscoelastic model was proposed to describe the rheological behavior of the isothermal thermoplastic polymer materials, based on the molecular kinetics, thermodynamics, and continuum mechanics method. The model is simplified as the generalized Newton’s law. Its integral formula with similar form to the K-BKZ model was also derived. Rheological experiments were carried out with the isotactic polypropylene material. The experimental results reveal that the viscoelastic model exhibits a three-stage rheological characteristic. There is a distinct high-elastic rheological region in the middle stage, reflecting the pseudoplastic fluids properties. Compared with the Ostwald-de Waele power law model, the viscoelastic model shows a better agreement with the rheological practices.
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
Corrected proof , doi: 10.1007/s10118-019-2197-0
[Abstract](167) [FullText HTML](48) [PDF 539KB](20)
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
Corrected proof , doi: 10.1007/s10118-019-2198-z
[Abstract](178) [FullText HTML](81) [PDF 827KB](28)
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
Corrected proof , doi: 10.1007/s10118-019-2205-4
[Abstract](126) [FullText HTML](62) [PDF 1315KB](7)
A series of polyamic acid copolymers (co-PAAs) with para-hydroxyl groups was 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′-biphenyltetracarboxylic dianhydride (BPDA) in N,N-dimethyacetamine (DMAc). The co-PAA solutions were used to fabricate fibers by dry-jet wet spinning, and thermal imidization was 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 (FTIR) spectroscopic results confirmed that intra/intermolecular hydrogen bonds originated 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 displayed homogenous and smooth surface and uniform diameter. The glass transition temperatures (Tgs) of PI fibers were within 311−337 °C. The polyimide fibers showed 5% weight loss temperature (T5%) at above 510 °C in air. Two-dimensional wide-angle X-ray diffraction (WXRD) patterns indicated that the homo-PI and co-PI fibers presented regularly arranged polymer chains along the fiber axial direction. The ordered molecular packing along the transversal direction was destroyed by introducing the m-pHBOA moiety. Moreover, the crystallinity and orientation factors increased with increasing draw ratio. Small-angle X-ray scattering (SAXS) results showed that it is beneficial to reduce defects in the fibers by increasing the draw ratio. The resultant PI fibers exhibited excellent mechanical properties with fracture strength and initial modulus of 2.48 and 89.73 GPa, respectively, when the molar ratio of p-PDA/m-pHBOA was 5/5 and the draw ratio was 3.0.
Nanomagnetic Organogel Based on Dodecyl Methacrylate for Absorption and Removal of Organic Solvents
Hossein Ghasemzadeh, Maryam Dargahi, Ghazaleh Eyvazi, Bahman Vasheghani Farahani
Corrected proof , doi: 10.1007/s10118-019-2213-4
[Abstract](78) [FullText HTML](60) [PDF 1171KB](4)
A novel nanomagnetic organogel was synthesized by in situ emulsion polymerization-crosslinking method using dodecyl methacrylate (DDMA) and styrene (St) as monomers, divinylbenzene (DVB) as a crosslinking agent, azobisisobutyronitrile (AIBN) as an initiator, and Fe3O4 as a nanomagnetic particle. Modification of the network was carried out by inclusion of the multi-walled carbon nanotubes (MWCNT) into the organogel matrix. The structure of the nanocomposite was characterized using FTIR spectroscopy, SEM, TEM, TGA/DTG, VSM, and BET analysis. The effects of various parameters such as the amount of crosslinker, initiator, Fe3O4, and reaction time as well as monomer ratio on the oil absorption of the organogel were studied. The synthesized organogel can absorb about 35.5, 22.1, 29.86, 14.58, 17.6, 15.3, and 13.7 g·g−1 of CHCl3, toluene, CH2Cl2, hexane, crude oil, gasoline, and diesel oil, under the optimized polymerization conditions, respectively. The nanocomposite organogels can be easily separated by a magnetic field after absorption of organic solvents.
Effects of Main-Chain and Chain-Ends on the Organogelation of Stearoyl Appended Pendant Valine Based Polymers
Mridula Nandi, Swagata Pan, Dipannita Ghosh, and Priyadarsi De
Accepted Manuscript , doi: 10.1007/s10118-019-2265-5
[Abstract](20) [PDF 1251KB](4)
In this article we establish the effect of hydrophobic interactions between the polymeric backbone and chain-end groups on the self-assembly pathway of stearoyl appended side-chain valine (Val)-based poly(methacrylate/acrylate) homopolymers in different organic hydrocarbons. Gelation studies conducted revealed that while polymers with poly(acrylate) as backbone induces gelation in several organic hydrocarbons, polymers with poly(methacrylate) in the main-chain significantly hinders macroscopic gelation. The morphology of the organogels were analysed by field emission scanning electron microscopy (FE-SEM), and mechanical strengths of organogels were determined by rheological measurements. Different reversible addition-fragmentation chain transfer (RAFT) polymerization chain transfer agents (CTA)s [R1-S-C=(S)-S-R2] with different -R1 and -R2 groups have been employed to study the effect of structural variation at the chain-end on macroscopic assembly mechanism. We observed that the additional interactions between terminal groups via hydrogen-bonding or π-π stacking interactions or both helps in the self-assembly pathway producing mechanically stable organogels.
Mechanical Properties of Interlocked-Ring Polymers: A Molecular Dynamics Simulation Study
Zhengtao Wu and Jiajia Zhou
Accepted Manuscript , doi: 10.1007/s10118-019-2279-z
[Abstract](0) [PDF 920KB](0)
Interlocked-ring polymers, also known as polycatenanes, possess an interesting molecular architecture. This polymer composes of a linear chain of many interlocked ring polymers. The topological constrain between neighboring rings distinguishes the interlockedring polymer from its linear counterpart. Here we present extensive molecular dynamics simulations on the interlocked-ring polymers and analyze the static properties of the polymer. By applying external forces to the polymer, we also study the force-extension curves of the polymer, which provides rich information about the mechanical properties of the interlocked-ring polymers.
A Well-defined Hierarchical Hydrogen Bonding Strategy to Polyureas with Simultaneously Improved Strength and Toughness
Ting Li, Tianze Zheng, Zhao-Xia Guo, Jun Xu, and Bao-Hua Guo
Accepted Manuscript , doi: 10.1007/s10118-019-2275-3
[Abstract](2) [PDF 5445KB](1)
A well-defined quadruple hydrogen bonding strategy involving dimerization of 2-ureido-4[1H]-pyrimidone (UPy) units is innovatively designed to prepare polyureas with high overall mechanical properties. Three polyureas containing different amounts of UPy units were synthesized by replacing a portion of isophorone diisocyanate (IPDI) with a UPy-derived diisocyanate. The formation of quadruple hydrogen bonds in hard segments via UPy dimers were confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the polyureas were evaluated by uniaxial tensile testing. Compared to the polyurea without UPy units, remarkable improvements in Young’s modulus, tensile strength and toughness were simultaneously achieved when UPy units were incorporated. The mechanism behind the strong strengthening effect was attributed to the stronger intermolecular forces among hard segments brought by the quadruple hydrogen bonds, which is stronger than the inherent bidentate and monodentate hydrogen bonds among urea groups, and the slower soft segmental dynamics reaveled by both increased Tg and relaxation time of the soft segments. The mechanism behind the strong toughening effect was ascribed to more effective energy dissipation brought by the quadruple hydrogen bonds serving as stronger sacrificial bonds upon deformation. This work may offer new insight into the design of polyurea elastomers with comprehensively improved mechanical properties.
Preparation and properties of ultrathin flexible expanded graphite film via adding natural rubber
Yan-Ling Mo, Yu-Xin Tian, Yu-Hang Liu, Feng Chen, Qiang Fu
Accepted Manuscript , doi: 10.1007/s10118-019-2264-6
[Abstract](25) [PDF 2276KB](11)
Expanded graphite (EG) films exhibit potential use in a wide field including thermal management, conductive applications and electromagnetic interference (EMI) shielding; but their poor tensile strength and brittleness are a crucial deficiency for commercial applications. To address this defect, in our work, natural rubber (NR) is employed to enhance EG films with excellent mechanical strength and flexibility. The origin of the strengthening effect of the EG films by the addition of natural rubber mainly arises via forming a simulate shell structure. Compared to the pure EG films, by only adding 2 wt% NR can give rise to a superior ductility. The loading of 10 wt% NR realizes a significant mechanical enhancement of the EG/NR films, i.e., a 2.4 and 11.4 times increase in tensile strength and elongation at break. Besides, EG/NR films contain 10 wt% NR can still remain excellent thermal and electric conductivities of 173 W m−1‧K−1, 75 S cm−1. Furthermore, a very high EMI of 41.4 dB is achieved as the film thickness reaches 50 μm. These comprehensive performance of lightweight EG/NR films, as well as their virtues of green and simple large-scale preparation endow the films with the possibility of designing next-generation flexible electronics.
Co-delivery of Doxorubicin and Afatinib with pH-responsive Polymeric Nanovesicle for Enhanced Lung Cancer Therapy
Heng-Ye Gong, Yan-Gui Chen, Xing-Su Yu, Hong Xiao, Jin-Peng Xiao, Yong Wang, and Xin-Tao Shuai
Accepted Manuscript , doi: 10.1007/s10118-019-2272-6
[Abstract](15) [PDF 1244KB](6)
Drug-resistance and drastic side effects are the two major issues of traditional chemotherapy which may result in trail failure even death. Nanoparticle mediated multidrug combination treatment has been proven to be a feasible strategy to overcome these challenges. In the present study, amphipathic block polymer of methoxyl poly(ethylene glycol)-poly(aspartyl(dibutylethylenediamine)-cophenylalanine) (mPEG-P(Asp(DBA)-co-Phe)) was synthesized and self-assembled into pH-responsive polymeric vesicle. The vesicle was utilized to co-deliver cancer-associated epidermal growth factor (EGFR) inhibitor of afatinib and DNA-damaging chemotherapeutic doxorubicin hydrochloride (DOX) for enhanced non-small-cell lung cancer (NSCLC) therapy. As evaluated in vitro, the pH-responsive design of nanovesicle resulted in a rapid release of encapsulated drugs into tumor cells and caused enhanced cell apoptosis. In addition, the in vivo therapeutic studies were conducted and the results evidenced that the co-delevery of DOX and afatinib using pH sensitive nanovector was a promising strategy for NSCLC treatment.
Dimethylacetamide-Promoted Direct Arylation Polycondensation of 6,6’-Dibromo-7,7’-diazaisoindigo and (E)-1,2-Bis(3,4-difluorothien-2-yl) ethene toward High Molecular Weight n-Type Conjugated Polymers
Kai Guo, Yu Jiang, Ying Sui, Yunfeng Deng, and Yanhou Geng
Accepted Manuscript , doi: 10.1007/s10118-019-2277-1
[Abstract](0) [PDF 878KB](0)
A highly efficient and eco-friendly protocol for the synthesis of an alternating copolymer poly(7,7’-diazaisoindigo-alt-(E)-1,2-bis(3,4-difluorothien-2-yl)ethene) (PAIID-4FTVT) via direct arylation polycondensation (DArP) is presented. Through detailed study, we found that the inhibitory effect of 7,7’-diazaisoindigo on DArP stemmed from the coordination of N atom with catalyst can be overcome by using dimethylacetamide (DMAc) as the co-solvent. Thus, PAIID-4FTVT with number-average molecular weight (Mn) >100 kDa was synthesized via DArP by optimizing the content of DMAc. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrum revealed that PAIID-4FTVT was defect-free. Top gate and bottom contact (BG/TC) organic thin-film transistors (OTFTs) were fabricated to characterize the semiconducting properties of the polymers. PAIID-4FTVT displayed unipolar n-type characteristics with the electron mobility (μe) strongly dependent on Mn. The highest μe up to 0.25 cm2V-1s-1 was achieved with the high molecular weight sample.
Inhomogeneous Natural Network Promoting Strain-induced Crystallization: A Mesoscale Model of Natural Rubber
Han Liu, Guangsu Huang, Laiyun Wei, Jian Zeng, Xuan Fu, Cheng Huang, Jinrong Wu
Accepted Manuscript , doi: 10.1007/s10118-019-2267-3
[Abstract](14) [PDF 1148KB](0)
Although synthetic rubbers show continuously improved mechanical properties, natural rubber (NR) remains irreplaceable among the rubber family due to its superior mechanical properties. A mainstream viewpoint regarding the superiority of NR is that NR possesses a natural network formed by linking the poly-cis-1, 4-isoprene chain terminals to protein and phospholipid aggregates; after vulcanization, the natural network additionally contributes to rubber mechanics by both increasing the network density and promoting the strain-induced crystallization (SIC) behavior. However, the reason why the natural network promotes SIC is still unclear; in particular, only using the increased network density cannot explain our finding that the NR shows smaller onset strain of SIC than Gel (the gel component of NR with higher network density) and even vulcanized NR. Herein, we point out that the inhomogeneous chain deformation is the alternative reason why the SIC of NR takes place at smaller strain than that of Gel. More specifically, although the natural network is homogenous on the subchain length scale based on the proton double-quantum NMR results, it is essentially inhomogeneous on mesoscale (100nm), as revealed by the small angle X-ray scattering analysis. This inhomogeneous network also leads to the mesoscale deformation inhomogeneity, as detected by the orientation of stearic acid (SA) probe, thus resulting in the smaller onset strain of SIC of NR. Based on the experimental results, a mesoscale model is proposed to qualitatively describe the crucial roles of inhomogeneous structure and deformation of natural network in NR’s mechanical properties, providing a clue from nature to guide the development of high-performance rubbers with controlled structures at mesoscale.
Miscibility and crystallization behavior of novel branched poly(ethylene succinate)/poly(vinyl phenol) blends
Kangjing Zhang, Zhaobin Qiu
Accepted Manuscript , doi: 10.1007/s10118-019-2269-1
[Abstract](12) [PDF 911KB](4)
The blends of novel branched poly(ethylene succinate) (b-PES) and poly(vinyl phenol) (PVPh) were prepared via a solution and casting method. The miscibility, melting behavior, spherulitic morphology and growth, and crystal structure of b-PES/PVPh blends were investigated in detail. PVPh was miscible with b-PES over the whole compositions as evidenced by the single composition dependent glass transition temperature. Double melting behavior occurred in neat b-PES and b-PES/PVPh 85/15 blend after isothermal melt crystallization, which may be explained by the melting, recrystallization, and remelting mechanism. In addition, the depression of equilibrium melting point of an 85/15 blend was also found, confirming again the miscibility between the two components. The addition of PVPh caused the decrease of nucleation density and crystal growth rates of b-PES spherulites in the blend. The crystal structure of b-PES was unchanged before and after the blending; moreover, the crystallinity of b-PES decreased slightly in the blend.
Synthesis and properties of a reversible disulfide bond-based self-healing polyurethane with triple shape memory properties
Han Jia, Kun Chang, and Shu-Ying Gu
Accepted Manuscript , doi: 10.1007/s10118-019-2268-2
[Abstract](12) [PDF 3045KB](0)
A reversible disulfide bond-based self-healing polyurethane with triple shape memory properties was prepared by chain extending of random copolymer poly(lactide-co-caprolactone) (PCLA), hexamethylene diisocyanate (HDI), polytetrahydrofuran (PTMEG) and 4,4’-aminophenyl disulfide. The chemical structures were characterized using 1H nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FT-IR), and gel permeation chromatographer (GPC). The thermal properties, self-healing properties, triple-shape memory effect and quantitative shape memory response were evaluated by differential scanning calorimetry (DSC), tensile tests, two-step programming process thermal mechanical experiments and subsequent progressive thermal recovery. The self-healing mechanism and procedures were investigated using a polarizing optical microscope (POM) and an optical profiler. It was concluded that self-healing properties (up to 60%) and triple shape memory properties around 35 C and 50 C (with shape fixation ratios of 94.3% and 98.3%, shape recovery ratios of 76.6% and 85.1%, respectively) were integrated to the shape memory polyurethane. The polyurethane is expected to have potential applications in multi-shape coatings, films and step-by-step deploying structures.
Cu(0) wire-mediated single-electron transfer-living radical polymerization of oligo(ethylene oxide) methyl ether acrylate by selecting the optimal reaction conditions
Liang Ding, Juan Li, Ruiyu Jiang, Lingfang Wang, Wei Song, and Lei Zhu
Accepted Manuscript , doi: 10.1007/s10118-019-2263-7
[Abstract](29) [PDF 3566KB](4)
The efficient Cu(0) wire-catalyzed single-electron transfer-living radical polymerization (SET-LRP) in organic solvents and mixtures of the organic solvents with water is thoroughly investigated. Oligo(ethylene oxide) methyl ether acrylate is used as exemplar oligomer monomer to determine the optimum polymerization conditions for rapid, controlled, and quantitative production of well-defined polymers. The effect of the Cu(0)-wire length (12.5 cm or 4.5 cm), the ligand (tris(dimethylaminoethyl)amine, Me6-TREN or tris(2-aminoethyl)amine, TREN), and the solvent (dipolar aprotic solvents, cyclic ethers, alcohol or acetone) on the polymerization has been evaluated. Kinetic experiments are performed for all polymerizations to assess the “living” behavior of each system employed. Importantly, TREN could be used as a replacement for Me6-TREN in Cu(0)-wire catalyzed SET-LRP of oligomer monomer, which probably provides the most economical and efficient methodology since TREN is 80 times less expensive than Me6-TREN. The high chain-end fidelity of resulting polymer was experimentally verified by thiol-Michael addition reaction at the α-Br chain end and subsequent chain extension with methyl acrylate.

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Chinese Journal of Polymer Science 2018 (Volume 37) Number 4 Contents
2019, 37(4) .  
[Abstract](55) [PDF 53313KB](9)
Recent Progress in AIE-active Polymers
Yu Bing Hu, Jacky W. Y. Lam, Ben Zhong Tang
2019, 37(4): 289 -301.   doi: 10.1007/s10118-019-2221-4
[Abstract](281) [FullText HTML](78) [PDF 1375KB](25)
The demand for highly efficient solid-state luminophores is continuously growing due to their potential applications in optoelectrical devices, chemosensors, and biological applications. The discovery of luminogens with aggregation-induced emission (AIE) by Tang et al. in 2001 provides a good reponse to this demand. Among the exploited AIE luminogens, AIE-active polymers possess many advantages such as simple synthesis, convenient structrue modifications, and good processability, which offer an extensive platform for scientists and engineers. Herein, the design principles and latest synthetic advancement of AIE-active polymers are summarized, including click polymerization and multicomponent polymerization. Non-conjugated heteroatom-rich polymers were in situ generated and demonstated non-conventional clusteroluminoscence. Advanced applications including fluorescent sensors, stimuli-responsive materials, biological applications, circularly polarized luminescence, and electroluminescence are then introduced in detail. AIE-active polymers display the signal-amplification effect for sensitive and selective response to chemo/bioanalytes or stimuli and enhanced photosensitization effect for cancer theranostics. Retrospecting the expansion of this field can further strengthen our belief that AIE-active polymers are promising for conceptual innovation and technological breakthroughs in the near future.
AIEgens-lightened Functional Polymers: Synthesis, Properties and Applications
Shi-Yuan Zhou, Hai-Bo Wan, Feng Zhou, Pei-Yang Gu, Qing-Feng Xu, Jian-Mei Lu
2019, 37(4): 302 -326.   doi: 10.1007/s10118-019-2217-0
[Abstract](160) [FullText HTML](55) [PDF 3245KB](18)
Recently, polymers with aggregation-induced emission (AIE) effects have attracted significant attention due to their broad applications in luminescence sensors, stimuli responsive materials, electroluminescence devices, etc. In this review, we summarize recent advances concerning AIE polymers. Four types of AIE polymers including end-functionalized polymers, side-chain polymers, main-chain polymers, and other polymers according to the location of AIEgens, are described. Their synthetic preparation, optical property, AIE effects, and applications are also illustrated in this review.
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
2019, 37(4): 327 -339.   doi: 10.1007/s10118-019-2207-2
[Abstract](163) [FullText HTML](62) [PDF 1425KB](11)
Tetraphenylethylene (TPE) derivatives are typical aggregation-induced emission (AIE) molecules, which have been widely investigated and applicated. The Rathore’s procedures and McMurry reaction are the two frequently used methods for synthesizing 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, named 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, and becomes 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 that GCC reaction will have a bright future in the development of the next generation of tetraarylethylene (TAE)-kind AIE materials.
Recent Advances and Progress for the Fabrication and Surface Modification of AIE-active Organic-inorganic Luminescent Composites
Liu-Cheng Mao, Xiao-Yong Zhang, Yen Wei
2019, 37(4): 340 -351.   doi: 10.1007/s10118-019-2208-1
[Abstract](179) [FullText HTML](59) [PDF 992KB](12)
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 diodes (LEDs). Nevertheless, conventional fluorescence molecules suffer from aggregation-caused quenching (ACQ) when they are doped into inorganic nanomaterials. Aggregation-induced emission (AIE) is an abnormal and intriguing fluorescent phenomenon that has aroused increasing interest for various applications especially in biomedical fields. Compared with conventional organic dyes, the AIE-active molecules will emit more intense fluorescence in their aggregates or solid states. 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 constructing various AIEgens-doped organic-inorganic hybrid nanocomposites and their subsequent surface modification were summarized. We hope this review could further promote the research of AIE-active functional materials.
Recent Progress in Fluorescent Vesicles with Aggregation-induced Emission
Hui Chen, Min-Hui Li
2019, 37(4): 352 -371.   doi: 10.1007/s10118-019-2204-5
[Abstract](200) [FullText HTML](88) [PDF 5576KB](17)
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 constitute 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.
AIE-active Metal-organic Coordination Complexes Based on Tetraphenylethylene Unit and Their Applications
Bo Jiang, Chang-Wei Zhang, Xue-Liang Shi, Hai-Bo Yang
2019, 37(4): 372 -382.   doi: 10.1007/s10118-019-2216-1
[Abstract](130) [FullText HTML](59) [PDF 1221KB](15)
Tetraphenylethylene (TPE) and its derivatives, as the widely used aggregation-induced emission (AIE) fluorophores, have attracted rapidly growing interest in the fields of material science and biological technology due to their unique light-emitting mechanism—they are nearly non-emissive in dilute solution but emit brilliant fluorescence in the aggregate state because of the restriction of intramolecular motion. Coordination-driven self-assembly, which provides a highly effective method to put the individual chromophores together, is consistent with the AIE mechanism of TPE. During the past few years, some AIE-active metal-organic coordination complexes have been successfully constructed via coordination-driven self-assembly, and their AIE properties and applications have been investigated. In this review, we survey the recent progress on TPE-based metal-organic coordination complexes and their applications in fluorescence sensors, cell imaging, and light-emitting materials. We will introduce them from three different types of structures: metallacycles, metallacages, and metal-organic frameworks (MOFs).
Recent Advances in Purely Organic Room Temperature Phosphorescence Polymer
Man-Man Fang, Jie Yang, Zhen Li
2019, 37(4): 383 -393.   doi: 10.1007/s10118-019-2218-z
[Abstract](227) [FullText HTML](84) [PDF 1550KB](31)
Room temperature phosphorescence (RTP) has drawn increasing attention for its great potential in practical applications. Polymers with large molecular weights and long chains tend to form coil, which can endow them with a high degree of possible rigidity and result in the much restricted non-radiative transition. Also, the intertwined structure of polymers could isolate the oxygen and humidity effectively, thus reducing the consumption of triplet excitons. In consideration of these points, organic polymers would be another kind of ideal platform to realize RTP effect. This short review summarized the design strategy of the purely organic room temperature phosphorescence polymers, mainly focusing on the building forms of polymers and the corresponding inherent mechanisms, and also gives some outlooks on the further exploration of this field at the end of this paper.
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
2019, 37(4): 394 -400.   doi: 10.1007/s10118-019-2201-8
[Abstract](142) [FullText HTML](77) [PDF 822KB](24)
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.
NIR Emission Nanoparticles Based on FRET Composed of AIE Luminogens and NIR Dyes for Two-photon Fluorescence Imaging
Lei-Jing Liu, Wen Liu, Guang Ji, Zhi-Yuan Wu, Bin Xu, Jun Qian, Wen-Jing Tian
2019, 37(4): 401 -408.   doi: 10.1007/s10118-019-2206-3
[Abstract](88) [FullText HTML](63) [PDF 707KB](7)
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 poly(ethylene glycol) (PEG) to increase the in vivo biocompatibility of the NPs. The PSMA@TB/NIR775 NPs showed a strong NIR (780 nm) narrow emission and excellent two-photon absorption property. Moreover, the NPs exhibited 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.
Clustering-triggered Emission of Cellulose and Its Derivatives
Lin-Lin Du, Bing-Li Jiang, Xiao-Hong Chen, Yun-Zhong Wang, Lin-Min Zou, Yuan-Li Liu, Yong-Yang Gong, Chun Wei, Wang-Zhang Yuan
2019, 37(4): 409 -415.   doi: 10.1007/s10118-019-2215-2
[Abstract](152) [FullText HTML](66) [PDF 992KB](13)
In recent years, nonconventional luminogens free of aromatic groups have attracted extensive attention due to their academic importance and promising wide applications. Whilst previous studies generally focused on fluorescence from aliphatic amine or carbonyl-containing systems, less attention has been paid to room temperature phosphorescence (RTP) and the systems with predominant oxygen functionalities. In this work, photophysical properties of the polyhydroxy polymers, including microcrystalline cellulose (MCC), 2-hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and cellulose acetate (CA), were studied and compared. While MCC, HEC, and HPC solids showed bright emission alongside distinct RTP, CA demonstrated relatively low intensity of solid emission without noticeable RTP. Their emissions were explained in terms of the clustering-triggered emission (CTE) mechanism and conformation rigidification. Additionally, on account of its intrinsic emission, concentrated HEC aqueous solution could be used as the probe for the detection of 2,4,6-trinitrophenol (TNP).
Synthesis and Properties of High Performance Functional Polyimides Containing Rigid Nonplanar Conjugated Fluorene Moieties
Yi-Wu Liu, Li-Shuang Tang, Lun-Jun Qu, Si-Wei Liu, Zhen-Guo Chi, Yi Zhang, Jia-Rui Xu
2019, 37(4): 416 -427.   doi: 10.1007/s10118-019-2225-0
[Abstract](96) [FullText HTML](46) [PDF 2142KB](10)
A diamine (WuFDA) containing vertical rigid non-planar conjugated fluorene moiety and low polarizability group (C―F) was designed and synthesized through three steps of reactions (halogenated reaction, Suzuki coupling reaction, and reduction reaction). Four kinds of high performance functional polyimides (WuFPI-6F, WuFPI-BP, WuFPI-BT, and WuFPI-PM) were thus prepared by the condensation polymerization of WuFDA with four commercial dianhydride 6FDA, BPDA, BTDA, and PMDA, respectively. The polyimides exhibited low dielectric constant, excellent thermal stability, outstanding solubility, good film-forming property, and mechanical properties. The dielectric constants of the polyimides were in the range of 2.28−2.88 (f = 104 Hz). The 5% weight-loss temperatures (Td5%) in nitrogen were in the range of 555−584 °C, and the glass transition temperatures (Tg) were in the range of 408−448 °C. The weight loss of WuFPI-BP maintaining at 450 and 500 °C for half an hour was only 0.33% and 1.26%, respectively. All the WuFPIs could be dissolved in almost all organic solvents, even chloroform. The tensile strength and tensile modulus of these films were in the ranges of 78.6−85.7 MPa and 3.1−3.2 GPa, respectively. In addition, the polyimides displayed light color with special fluorescent and resistive switching (ON-OFF) characteristics; the maximum fluorescence emission was observed at 422−424 nm in NMP solution and at 470−548 nm in film state. The memory devices with the configuration of indium tin oxide/WuFPIs/aluminum (ITO/WuFPIs/Al) exhibited distinct volatile memory characteristics of static random access memory (SRAM), with an ON/OFF current ratio of 105−106. These functional polyimides showed attractive potential applications in the field of high performance flexible polymer photoelectronic devices or polymer memory devices.
Aggregation-induced Emission-active Hyperbranched Poly(tetrahydro-pyrimidine)s Synthesized from Multicomponent Tandem Polymerization
Yuzhang Huang, Ping Chen, Bo Wei, Rongrong Hu, Ben Zhong Tang
2019, 37(4): 428 -436.   doi: 10.1007/s10118-019-2230-3
[Abstract](74) [FullText HTML](40) [PDF 961KB](6)
Hyperbranched polymer with highly branched three-dimensional topological structure, a large number of end groups, and multifaceted functionalities have gained much attention, while polymers with aggregation-induced emission (AIE) properties become a group of popular luminescent materials recently. The design and synthesis of AIE-active hyperbranched polymers, which combine the advantages of these two types of materials, are attractive but challenging. In this work, four hyperbranched poly(tetrahydropyrimidine)s were synthesized from the metal-free room temperature multicomponent tandem polymerization of diester group-activated internal alkyne, polyfunctional aromatic amines, and formaldehyde in methanol under the catalysis of acetic acid. Through different monomer combination and controlling the monomer loading order, hyperbranched polymers with various topological structures as well as sequences of different functional groups in the polymer backbone were obtained with high molecular weights (up to 3.0 × 104 g/mol) in high yields (up to 98%). The hyperbranched poly(tetrahydropyrimidine) emitted faintly in solution, while its luminescence was notably enhanced in the aggregated state, suggesting its typical aggregation-induced emission property. It is anticipated that the multicomponent polymerization may provide a synthetic platform for the construction of hyperbranched polyheterocycles with diverse structures and functionalities.