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COPOLYMERIZATION OF ETHYLENE AND 1-HEXENE WITH TiCl_4/MgCl_2 CATALYSTS MODIFIED BY 2,6-DIISOPROPYLPHENOL

Chinese Journal of Polymer Science 2013年第1期31卷 110-121页

作者： Sheng-jie Xia Zhi-sheng Fu Xiao-yan Liu 范志强 MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang University

A supported TiCl4/MgCl2 catalyst without internal electron donor （O-cat） was prepared firstly. Then it was modified by 2,6-diisopropylphenol to make a novel modified catalyst （M-cat）. These two catalysts were used to catalyze ethylene/l-hexene copolymerization and l-hexene homopolymerization. The influence of cocatalyst and hydrogen on the catalytic behavior of these two catalysts was investigated. In ethylene/l-hexene copolymerization, the introduction of 2,6- iPr2C6H3O- groups did not deactivate the supported TiCl4/MgCl2 catalyst. Although the 1-hexene incorporation in ethylene/1- hexene copolymer prepared by M-cat was lower than that prepared by O-cat, the composition distribution of the former was narrower than that of the latter. Methylaluminoxane （MAO） was a more effective activator for M-cat than triisobutyl- aluminium （TIBA）. MAO led to higher yield and more uniform chain structure. In 1-hexene homopolymerization, the presence of 2,6-ipr2C6H3O- groups lowered the propagation rate constants. Two types of active centers with a chemically bonded 2,6-iprzCaH3O- group were proposed to explain the observed phenomena in M-cat.

关键词： Supported Ziegler-Natta catalyst 2,6-Diisopropylphenol Ethylene copolymerization Active center distribution.

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Reconstruction of Core-Shell Dispersed Particles in Impact Polypropylene Copolymer during Extrusion

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Chinese Journal of Polymer Science 2015年第4期33卷 633-645页

作者： Feng Chen Bi-wei Qiu Ya-nan Ye Yu-hua Lv 上官勇刚 Yi-hu Song 郑强 MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang University

We reported an approach to reconstruct the complex phase morphology of impact polypropylene copolymer （IPC） with core-shell dispersed particles and to optimize its toughness in approximate shear condition. The molten-state annealing results indicate that the phase structure with core-shell dispersed particles is unstable and could be completely destroyed by static annealing, resulting in the degradation of impact strength. By using a co-rotating twin screw extruder, we found that the dispersed particle with core-shell structure could be rebuilt in appropriate condition with the recovery of excellent impact strength due to both the huge interfacial tension during solidification and the great difference in viscosity of components. Results reveal that almost all the extruded IPCs show the impact strength 60%-90% higher than that of annealed IPCs at room temperature. And the twice-extruded IPC shows the highest impact strength, 446% higher than that of IPC annealed for 30 min. As for low temperature tests, the impact strength of extruded IPCs also increases by 33%-58%. According to adjusting the processing conditions including extrusion speed, extrusion frequency and temperature, an optimization of toughness was well established.

关键词： Impact polypropylene copolymer Shear Phase morphology Core-shell dispersed particle Impact strength.

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Mechanism of Janus Polymerization: A DFT StudyFig. S3 Energy profiles of anionic polymerization in Stage I under B3LYP/6-31G(d,p)(blue) and B3LYP/aug-cc-p VTZ//B3LYP/6-31G(d,p)(red). Scheme S1. Propagation process of CL/THF on cationic side in Stage I of J

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Chinese Journal of Polymer Science 2019年第10期37卷 990-994,I0004页

作者： Tian-Wen Bai Xu-Feng Ni Jun Ling Zhi-Quan Shen Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Janus polymerization is featured as a combination of cationic and anionic growing ends in one living polymer chain. In the copolymerization of THF and CL catalyzed by lutetium triflates and initiated by propylene oxide, three stages are identified by kinetic study including(1) fast cationic polymerization with slow anionic one,(2) fast anionic polymerization with dormant cationic one, and(3)reactivation of cationic polymerization with coupling of anionic and cationic chain ends. In this work, density functional theory(DFT)calculation is employed to investigate the reaction details of ionic polymerization and dormancy. A “tripedal crow” configuration is proposed to illustrate the unique high-coordinated ligand exchange configuration in anionic polymerization in different stages. The trigger of dormancy is determined as chain structures rather than concentration of triflate anion according to both calculation and experimental results.

关键词： Rare earth metal catalysts Ring-opening polymerization Ionic polymerization Reaction mechanism Quantum chemicalcomputation

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Effects of Composition on Microstructure and Crystallization Behavior for Impact Polypropylene Copolymer Investigated by Restructuring the Complex Core-Shell Dispersed Particles in Ternary Blends

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Chinese Journal of Polymer Science 2015年第1期33卷 95-108页

作者： Bi-wei Qiu Feng Chen 上官勇刚 Yu Lin 郑强 MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang University

A series of ternary blends of polypropylene/ethylene-propylene random copolymer/ethylene-propylene segmented copolymer（HPP/EPR/Eb P） whose microstructures are similar to those of impact polypropylene copolymer（IPC） were prepared in order to systematically investigate the effects of composition on microstructure and crystallization behavior of IPC. The observation of primary phase morphology reveals that the dispersed phase with core-shell structure could be rebuilt in certain composition and excessive EPR leads to a bicontinuous phase structure in ternary blends. After undergoing same quiescent crystallization including isothermal and non-isothermal crystallization, these blend samples exhibit special composition-dependent melting behavior, i.e., the melting point increases markedly with the increase of EPR content until it turns down at a critical content（about 30 wt%）. The crystallization behavior is mainly ascribed to the different nucleation abilities. It is suggested that although the compatibility between EPR and HPP components becomes worse with the increase of EPR content due to the increased interfacial area and the decreased concentration of Eb P, higher EPR content in the blend facilitates to heterogeneous nucleation except for the appearance of obvious bicontinuous phase structure.

关键词： Core-shell dispersed phase Microstrcture Crystallization Nucleation.

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MULTILAYERS AND POLY(ALLYLAMINE HYDROCHLORIDE)-GRAFTPOLY(ETHYLENE GLYCOL) MODIFIED BOVINE SERUM ALBUMIN NANOPARTICLES:IMPROVED STABILITY AND pH-RESPONSIVE DRUG DELIVERY

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Chinese Journal of Polymer Science 2012年第5期30卷 719-726页

作者： Li-li Xie 仝维鋆 Jian-quan Xu Chang-you Gao MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang University

To improve the colloidal stability of bovine serum albumin （BSA） nanoparticles （hiPs） in diverse mediums, poly（allylamine hydrochloride）（PAH）/sodium poly（4-styrene sulfonate）（PSS） multilayers and poly（allylamine hydrochloride）-graft-poly（ethylene glycol）（PAH-g-PEG） coating were coated on the surface of BSA NPs. Stabilities of the BSA NPs in diverse mediums with different surfaces were detected by dynamic light scattering （DLS）. Multilayers and PAH-g-PEG coated BSA NPs can be well dispersed in various mediums with a narrow polydispersity index （PDI）. The BSA NPs with the highest surface density of PEG show the best stability. The multilayers and PAH-g-PEG coating do not deter the pH-dependent loading and release property of BSA NPs. At pH 9, the encapsulation efficiency of doxorubicin reaches almost 99%, and the release rate at pH 5.5 is significantly higher than that at pH 7.4.

关键词： BSA nanoparticle PEG LBL Drug delivery pH-responsive.

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PERVAPORATION FOR SEPARATING BENZENE/CYCLOHEXANE MIXTURE BY P(AA-MA) COPOLYMER MEMBRANES

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Chinese Journal of Polymer Science 2011年第3期29卷 288-295页

作者：朱蔚璞 Department of Polymer Science and Engineering Key Laboratory of Macromolecular Synthesis and Functionalization (Ministry of Education)Zhejiang University

P（AA-MA） copolymers composed of acrylic acid and methyl acrylate with different molecular weights and sequence structures were synthesized by combination of ATRP and selective hydrolysis. These copolymers were used as membrane materials to separate benzene/cyclohexane mixture by pervaporation. The effects of molecular weight and sequence structure of the copolymers on the pervaporation performance were investigated in detail. For the random copolymers, the permeate flux decreased rapidly with the increasing of molecular weight. The separation factor was also influenced by the molecular weight, which was changed from no selectivity to cyclohexane selectivity with increasing the molecular weight. Contrarily, the block copolymer membrane showed good benzene selectivity with separation factor of 4.3 and permeate flux of 157 g/（m2h） to 50 wt% benzene/cyclohexane mixture.

关键词： Pervaporation ATRP Copolymer Molecular weight Sequence structure Benzene/cyclohexane mixture.

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synthesis AND PROPERTIES OF ORGANIC-INORGANIC HYBRID P(NIPAM-co-AM-co-TMSPMA)MICROGELS

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Chinese Journal of Polymer Science 2011年第4期29卷 439-449页

作者：杜滨阳 MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science & Engineering Zhejiang University

Utilizing the hydrolysis and condensation of the methoxysilyl moieties, organic-inorganic hybrid poly（N- isopropylacrylamide-co-acrylamide-co-3-（trimethoxysilyl）propylmethacrylate） P（NIPAM-eo-AM-eo-TMSPMA） microgels were prepared via two different methods. The first method was that the microgels were post-fabricated from the cross- linkable linear P（NIPAM-co-AM-co-TMSPMA） terpolymer aqueous solutions above the lower critical solution temperature （LCST） of the terpolymer. For the second method, the mierogels were directly synthesized by conventional surfactant free emulsion copolymerization of NIPAM, AM, and TMSPMA. The hydrodynamic diameter and stability of the resultant P（NIPAM-co-AM-co-TMSPMA） microgels strongly depend on the pH and temperature of the microgel aqueous solution. The hydrodynamic diameters of the microgels decreased with increasing the measuring temperature. The phase transition temperature of the microgels was found to be around 34℃, which was independent of the initial terpolymer concentration and shifted to lower temperature with increasing the preparation temperature. Increasing the initial amount of AM will enhance the instability of the microgels at high pH values. Moreover, the P（NIPAM-co-AM-eo-TMSPMA） microgels obtained from the linear terpolymer had more homogeneous microstructures as compared with the corresponding NIPAM/AM/TMSPMA microgels prepared by one step emulsion copolymerization as revealed by light scattering measurements.

关键词： Microgel Thermo-sensitive Hybrid.

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Mediating the Migration of Mesenchymal Stem Cells by Dynamically Changing the Density of Cell-selective Peptides Immobilized on β-Cyclodextrin-modified Cell-resisting Polymer Brushes

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Chinese Journal of Polymer Science 2020年第2期38卷 126-136,I0005页

作者： Wang Du De-Teng Zhang Xue-Mei Wang Tan-Chen Ren Chang-You Gao Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Dynamic control of mesenchymal stem cell(MSC)behaviors on biomaterial surface is critically involved in regulating the cell fate and tissue ***,a stimuli-responsive surface based on host-guest interaction with cell selectivity was developed to regulate migration of MSCs in situ by dynamic display of cell-specific ***-grafted MSC-affinitive peptides(EPLQLKM,Azo-E7)were grafted toβ-cyclodextran(β-CD)-modified poly(2-hydroxyethyl methacrylate)-b-poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate)(PHG)brushes,which were prepared by using surface-initiated atom transfer radical polymerization(SI-ATRP).X-ray photoelectron spectroscopy(XPS),quartz crystal microbalance(QCM),and water contact angle were used to characterize their structure and *** adhesion assay showed that the combination effect of resisting property of PHG and MSC-affinity of E7 could promote the selective adhesion of MSCs over other types of cells such as RAW264.7 macrophages and NIH3 T3 fibroblasts to some ***-Vis spectroscopy proved that the competing guest molecules,amantadine hydrochloride(Ama),could release Azo-E7 peptides from the CD surface to different extents,and the effect was enhanced when UV irradiation was employed *** a result,the decrease of cell adhesion density and migration rate could be achieved in *** cell density and migration rate could be reduced by over 40%by adding 20μmol/L Ama,suggesting that this type of surface is a new platform for dynamic regulation of stem cell behaviors in situ.

关键词： Host-guest interaction MSC-affinitive peptide Dynamic surface Cell adhesion Cell migration

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Facile synthesis of Functional Poly (ε-caprolactone) via Janus Polymerization

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Chinese Journal of Polymer Science 2019年第9期37卷 858-865页

作者： Huan Qiu Zhe-Ning Yang Jun Ling Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

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(CLb-(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 sei住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 onestep Janus polymerization and precise post-polymerization click reaction.

关键词： Janus polymerization Functional poly(ε-caprolactone) Poly(3,3-bis(chloromethyl)oxacyclobutane) Ring-opening polymerization Rare earth metal catalysts

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Tough Poly(L-DOPA)-containing Double Network Hydrogel Beads with High Capacity of Dye Adsorption

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Chinese Journal of Polymer Science 2018年第11期36卷 1251-1261页

作者： Pei-Bin Zhang An-Qi Tang Zhang-Hui Wang Jing-Yu Lu Bao-Ku Zhu Li-Ping Zhu Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Zhejiang University

Developing a low-cost and well-recyclable adsorbent with high adsorption capacity is greatly desirable in dye wastewater treatment. Here, we demonstrate a kind of novel tough and reusable hydrogel beads with quite high capacity of dye adsorption via incorporating mussel-bioinspired poly（L-DOPA）（PDOPA） into alginate/poly（acrylamide） double network （DN） hydrogels. The synthesized PDOPA nanoaggregates were introduced into the DN hydrogels by simple one-pot mixing with the monomers prior to polymerization. The fabricated hydrogel beads exhibited high mechanical strength and good elastic recovery due to the interpenetrating Ca2＋-alginate and poly（acrylamide） networks. It was shown that the beads exhibited relatively high dye adsorption capacity compared to other adsorbents reported in literature, and the introduction of PDOPA with an appropriate amount raised the adsorption capacity. It is believed that the addition of PDOPA and the matrix of double network architecture contributed synergistically to the high adsorption capacity of hydrogel beads. Moreover, the desorption of dyes could be easily realized via rinsing in acidic water and ethanol solution. The hydrogel beads remained the high adsorption capacity even after 5 times of adsorption and desorption cycles. This tough and stable hydrogel with high adsorption capacity may have potential in treatment of dye wastewater released by textile dyeing industry.

关键词： Dye adsorption Hydrogel beads Poly（L-DOPA） Double network High strength

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