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Dynamic behavior of polymer surface and the time dependence of contact angle

science China Chemistry 2005年第6期48卷 553-559页

作者： WANG Xinping1, CHEN Zhifang1 & SHEN Zhiquan2.1. Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Education Ministry, department of Applied Chemistry, zhejiang Institute of{2. and Technology, hangzhou 310033, China 2. department of polymer science and engineering, zhejiang university, hangzhou 31002., China 1. department of Applied Chemistry Zhejiang Institute of Science and Technology Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Education Ministry 310033 Hangzhou China 2. department of polymer science and engineering Zhejiang University 310027 Hangzhou China

Time-dependent contact angles were measured by depositing sessile drops of wa-ter on the polymer surfaces and monitoring the drop shape as a function of time. It was found that contact angles decreased sharply with contact time and the equilibrium contact angle was finally attained after a certain time. Values of starting (θ s) and equilibrium contact angles (θ e) obtained by the sessile drop method depend on polymer properties. The Wilhelmy plate technique was used to measure advancing and receding contact angles. The variations of starting (θ s) and equilibrium contact angles (θ e), advancing (θ a) and receding contact angles (θ r) have been studied on the oxidized surface of polymers containing polybutadiene block to explore the cause of time-dependence in contact angle measurement and the meaning of θ s and θ e. The results showed the linear relationships between starting (θ s) and advancing contact angles (θ a), the equilibrium (θ e) and receding contact angles (θ r). The similar relationship was also established between the contact angle hysteresis (θ a?θ r) and differences (θ s ?θ e) in starting contact angles and equilibrium contact angles. Therefore, time-dependence in contact angle measurement was mainly attributed to the surface reconstruction when water drops were deposited on polymer surfaces. The starting contact angle was contributed by the hydrophobic component on polymer surface and the equilibrium contact angle mainly by the hydrophilic component of polymer. These results not only demonstrated the interdependency between two contact angle measurements, the sessile drop method and the Wilhelmy plate technique, but also provided the experimental evidence to explain the cause of time-dependent contact angle. This may also provide a new method to study dynamic behavior of polymer surface.

关键词： contact angle, surface dynamic behavior, polymer surface, dynamic contact angle, time-dependence.

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A NOVEL RESISTIVE HUMIDITY SENSOR BASED ON SODIUM POLYSTYRENESULFONATE/TiO_2.NANOCOMPOSITES

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Chinese Journal of polymer science 2002年第3期20卷 237-241页

作者： Yang Li Mu-jie Yang Yong She department of polymer{2. and engineering zhejiang university, hangzhou 31002. China zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

A resistive humidity sensor was prepared based on sodium polystyrenesulfonate (NaPSS)/TiO2.nanocomposites, and its electrical response to humidity was examined. The sensor exhibits better linearity, smaller hysteresis (2.s; desorption: less than 2. s) in comparison with sensor composed of NaPSS. The effect of concentration of NaPSS and TiO2.on humidity response of sensors was discussed.

关键词： humidity sensor nanocomposites TiO2 sodium polystyrenesulfonate

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GRAFTING OF HYDROPHILIC MONOMERS ONTO POLYURETHANE MEMBRANES BY SOLUTION OR PRE-ABSORBING METHODS FOR ACCELERATION OF CELL COMPATIBILITY

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Chinese Journal of polymer science 2001年第5期19卷 493-498页

作者： Chang-you Gao Jian-jun Guan Jia-cong Shen department of polymer{2. and engineering zhejiang university hangzhou 31002., China zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

Two grafting methods, i.e. solution grafting and pre-adsorbing, are introduced to covalently immobilizehydrophilic polymers on segmented polyurethane (SPU) to modify its hydrophilicity and to improve its cell *** grafting results in higher degree of grafting and rougher surface morphology. Cell culture evaluation demonstratesthat the modified membranes thus obtained are disadvantageous to the endothelial cell (ECs) growth probably because thehydrophilic groups on the surface are over-crowded. However, pre-absorbing grafting generates lower degree of grafting,which is detected and confirmed by ATR-FTIR spectra and water conted angle. Scanning electron microscopic (SEM)measurement shows that the latter method produces a plane and smooth morphology, which is similar to the SPU controlsample controlled. When grafting with lower monomer concentration, ECs could grow on SPU-g-PHEA [poly(2.hydroxyethyl acrylate)], SPU-g-PAAm (polyacrylamide), SPU-g-PDMA [poly(2.(dimethylamino)ethyl methacrylate)] orquatemized SPU-g-PDMA surface with elongated cell shapes. Hence, the cell compatibility of SPU is improved and a usefulmethod to construct a cell compatible layer on the polymer surface has been developed.

关键词： segmented polyurethane cell compatibility surface grafting endothelial cell

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RANDOM COpolymer OF PROPYLENE OXIDE AND ETHYLENE OXIDE PREPARED BY DOUBLE METAL CYANIDE COMPLEX CATALYST

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Chinese Journal of polymer science 2002年第5期20卷 453-459页

作者： Yi-jun Huang Guo-rong Qi Guan-xi Chen department of polymer{2. and engineering, zhejiang university hangzhou 31002.,China zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

Copolymerization of propylene oxide (PO) and ethylene oxide (EO) using double metal cyanide (DMC) complex as the catalyst was carried out. The structure of random copolymers was confirmed by C-13-NMR and IR spectra. H-1-NMR analysis shows that the EO content in the copolymer is the same as that in the initial monomer feed. Moderate molecular weight copolymers with various EO content were obtained and their values of molecular weight distribution (MWD) fell in the range of 1.2.-1.55. It was found that the molecular weight of copolymers is controlled by the mass ratio of EO+PO to initiator moles used, The reaction rate as well as polymer yield decrease with increasing EO content in the feed composition.

关键词： propylene oxide ethylene oxide double metal cyanide complex

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Correlation between rheological behavior and structure of multi-component polymer systems

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science China Chemistry 2008年第1期51卷 1-12页

作者： ZUO Min1,2.ZHENG Qiang1 1 Key Laboratory of Macromolecular Synthesis and Functionalization, Ministry of Education, department of polymer{2. and engineering, zhejiang university, hangzhou 31002., China 2.department of Chemical engineering, Hong Kong university of{2. and Technology, Clear Bay, Kowloon, Hong Kong 1. Key Laboratory of Macromolecular Synthesis and Functionalization Ministry of Education Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China 2. department of Chemical engineering Hong Kong University of Science and Technology Clear Bay Kowloon Hong Kong China

Rheological measurement has been an effective method to characterize the structure and properties for multiphase/multi-component polymers, owing to its sensitivity to the structure change of hetero- geneous systems. In this article, recent progress in the studies on the morphology/structure and rheological properties of heterogeneous systems is summarized, mainly reporting the findings of the authors and their collaborators, involving the correlation between the morphology and viscoelastic relaxation of LCST-type polymer blends, the microstructure and linear/nonlinear viscoelastic behavior of block copolymers, time scaling of shear-induced crystallization and rheological response of poly- olefins, and the relationship between the structure/properties and rheological behavior of filled polymer blends. It is suggested that a thorough understanding of the characteristic rheological response to the morphology/structure evolution of multiphase/multi-component polymers facilitates researchers’ op- timizing the morphology/structure and ultimate mechanical properties of polymer materials.

关键词： heterogeneous polymer systems morphology and structure rheological properties viscoelastic relaxation

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Effect of polymerization Temperature on Propylene polymerization with C_s-symmetric Metallocene Catalyst

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Chinese Chemical Letters 2000年第2期11卷 167-170页

作者： Zhi Qiang FAN Tariq YASIN Lin Xian FENG (department of polymer{2. and engineering, zhejiang university, hangzhou 31002.) zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

A novel highly active C-s-symmetric metallocene catalyst namely: meso-dimethylsilylbis (2.4,6-trimethyl-1 -indenyl)zirconium dichloride is presented. The effect of polymerization temperature (0-70 degrees C) on the catalyst performance for propylene polymerization has been investigated. This catalyst shows very high activity at 50 degrees C which is higher than the activity of the racemic analogue, and the resulted polypropylene is amorphous in nature with isotactic pentad content [mmmm] of 12.%.

关键词： polymerization metallocene catalyst propylene

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Synthesis of a novel perylene diimide derivative and its charge transfer interaction with C_(60)

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science China Chemistry 2008年第2期51卷 152-157页

作者： LIU Bo1,2. SHI MinMin1,2. YANG LiGong1,2. CHEN HongZheng1,2.& WANG Mang1,2.1 State Key Lab of Silicon Materials, department of polymer{2. and engineering, zhejiang university, hangzhou 31002., China 2.Key Laboratory of Macromolecule Synthesis and Functionalization of Ministry of Education, zhejiang university, hangzhou 31002., China 1. State Key Lab of Silicon Materials Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China 2. Key Laboratory of Macromolecule Synthesis and Functionalization of Ministry of Education Zhejiang University Hangzhou 310027 China

A novel organic electron acceptor, N,N′-dipyrimidinyl-3,4,9,10-perylene-tetracarboxylic diimide (DMP), was designed and synthesized. The molecular structure was characterized by FTIR spectrum and elemental analysis. By cyclic voltammetry measurements, DMP was found to possess a lower LUMO energy level than N,N′-diphenyl-3,4,9,10-perylene-tetracarboxylic diimide due to the stronger electron-withdrawing pyrimidinyl group than the phenyl group. Fluorescence quenching is observed in a dual-layer film consisting of a DMP layer and a C60 layer and was attributed to the charge transfer at the interface due to the energy level offset between DMP and C60.

关键词： perylene diimide LUMO charge transfer fluorescence quenching

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STEREOCHEMICAL CONTROL IN PROPYLENE polymerIZATION CATALYZED BY UNBRIDGED METALLOCENE CATALYSTS

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Chinese Journal of polymer science 2001年第4期19卷 407-413页

作者： Yin-bang Zhu Zhi-qiang Fan Tariq Yasin Lin-xian Feng department of polymer{2. and engineering zhejiang university hangzhou 31002., China zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

Two unbridged metallocene catalysts, bis(2.4,7-trimethylindenyl)zirconium dichloride (met-I) and bis(2.4,6-trimethylindenyl)zirconium dichloride (met-II), which are different in the position of substituents on the six-membered ring of the indenyl ligands were synthesized. The effect of substituents in the two metallocenes on the propylene polymerization was studied in the presence of methylaluminoxane (MAO) and triisobutylaluminium (TIBA). From the analysis of microstructure determined by C-13-NMR, it was demonstrated that the polymers produced by met-II have higher [mmmm] isotactic sequences than that of met-I. Using a mechanism based on model statistical analysis, it was found that chain-end model was dominant for met-I. However, met-II obeys the concurrent two-sites model during polymerization, which can be attributed to the existence of 'racemic-like' conformer in its system.

关键词： unbridged metallocene propylene polymerization elastomeric polypropylene stereochemical mechanism

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Lanthanum heterocyclic Schiff-base complex initiated ring-opening polymerization of ε-caprolactone

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Chinese Chemical Letters 2007年第9期18卷 1133-1136页

作者： Wen Lin Wei Lin Sun Zhi Quan Shen department of polymer{2. and engineering,zhejiang university,hangzhou 31002.,China department of polymer{2. and engineering Zhejiang University Hangzhou 310027 China

Lanthanum complex supported by the heterocyclic Schiff-base ligand of N-(2.pyridyl)-3,5-di-tert-butyl-salicylaldimine was prepared and employed for the ring-opening polymerization(ROP)ofε-caprolactone(ε-CL).The polymers obtained with this initiator showed a unimodal molecular weight distribution implied that only one active species was *** study revealed that the polymerization proceeds via acyl-oxygen bond cleavage.

关键词： Heterocyclic Schiff-base Rare earth complex ε-Caprolactone Ring-opening polymerization

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RING-OPENING polymerIZATION OF TRIMETHYLENE CARBONATE BY CALIX[8]ARENE-NEODYMIUM

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Chinese Journal of polymer science 2000年第1期18卷 77-80页

作者： Ling Ge Zhi-quan Shen Yi-feng Zhang Qiao-hong Huang department of polymer{2. and engineering, zhejiang university, hangzhou 31002., China zhejiang Univ Dept Polymer Sci & Engn Hangzhou 310027 Peoples R China

Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were investigated in detail. It was found that calix[8]arene-neodymium is a highly effective catalyst for the bulk polymerization of TMC and gives high molecular weight (M-v = 60,000) polymer. The optimum conditions of TMC polymerization were found to be as follows:TMC/Nd (molar ratio) = 2.000, 80 degrees C, 16 h. The polymers were characterized by NMR, GPC and DSC. Studying the mechanism by NMR showed that the polymerization of TMC catalyzed by calix[8]arene-neodymium proceeds via a cationic mechanism.

关键词： ring-opening polymerization trimethylene carbonate calixarene-neodymium

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