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Chinese Journal of Polymer Science 2005年第6期23卷 635-642页

作者： Qing-de Chen Xing-hai Shen and hong-cheng gao department of applied chemistry,college of chemistry and molecular engineering,peking university,beijing 100871,china department of applied chemistry College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

In the UV-Vis spectra of pure light-scattering systems, there is an exponential relationship between absorbance and wavelength （A = Kλ^-n）. Here, the exponent n is named as flocculation-coagulation parameter. In the present paper, the effects of different additives on the stability of poly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine）（poly（Bis-co-4-VP）） microgel dispersion were studied in detail via this parameter. The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups, making the microgel positively charged on its surface. This was confirmed by the measurement of Zeta potential and the result of conductometric titration. The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content.

关键词： Microgel dispersion(s) 4-Vinylpyridine Flocculation-coagulation parameter Zeta potential

EFFECTS OF L-PHENYLALANINE ON THE RADIATION SYNTHESIS OF POLY(N,N'-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE)(MICRO)GELS

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Chinese Journal of Polymer Science 2005年第6期23卷 643-650页

The effects of L-phenylalanine （L-Phe） on the synthesis ofpoly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine）（poly（Bis-co-4-VP））（micro）gels by γ-ray irradiation were studied. The addition of L-Phe could not only decrease the gelation dose （Dg） of the synthesis obviously, but also transform the morphology of copolymer from microgel to gel. In addition, the swelling ability of the （micro）gels was also affected in the presence of L-Phe. The decrease of Dg was ascribed to the effect of pH, while the transformation of the morphology was ascribed to the effect of L-Phe on the stability of the poly（Bis-co-4-VP） microgel. Such an effect was confirmed further as compared with the effects of L-alanine, L-glutamic acid, L-arginine, sulfuric acid and aqueous ammonia.

关键词： L-Phenylalanine γ-Ray irradiation Gelation dose Morphology transformation (Micro)gel

Systematic study of the transfer of amino acids across the water/1,2-dichloroethane interface facilitated by dibenzo-18-crown-6

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Science china chemistry 2004年第1期47卷 24-33页

作者： CHEN Yong, YUAN Yi, ZHANG Meiqin, LI Fei, SUN Peng, gao Zhao & SHAO YuanhuaState Key Laboratory of Electroanalytical chemistry, Changchun Institute of applied chemistry, Chinese Academy of Sciences, Changchun 130022, china college of chemistry and molecular engineering, peking university, beijing 100871, china Lab. of Electroanalytical Chem. Changchun Inst. of Appl. Chem. Chinese Acad. of Sci. Changchun 130022 China Coll. of Chem. and molecular Eng. Peking Univ. Beijing 100871 China

Facilitated ion transfer reactions of 20 amino acids with dibenzo-18-crown-6 (DB18C6) at the water/1,2-dichloroethane (W/DCE) interfaces supported at the tips of micro- and nano-pipets were investigated systematically using cyclic voltammetry. It was found that there were only 10 amino acids, that is, Leu, Val, lie, Phe, Trp, Met, Ala, Gly, Cys, Gin (in brief), whose protonated forms as cations can give well-defined facilitated ion transfer voltammograms within the potential window, and the reaction pathway was proven to be consistent with the transfer by interfacial complexation/dissociation (TIC/TID) mechanisms. The association constants of DB 18C6 with different amino acids in the DCE (β0), and the kinetic parameters of reaction were evaluated based on the steady-state voltammetry of micro- or nano-pipets, respectively. The experimental results demonstrated that the selectivity of complexation of protonated amino acid by DB18C6 compared with that of alkali metal cations was low, which can be attributed to the vicinal effect arising from steric hindrance introduced by their side group and the steric bulk effect by lipophilic stabilization. Moreover, the association constants and the standard rate constants for different amino acids showed good correlations with their hydrophobicity (π), except Gly and Met, which inferred that the selectivity of such heterogeneous complex reaction for different amino acids with DB18C6, was not only affected by discrimination in binding these ions to the crown ether macro-cycle, but also significantly modified by the ion transfer Gibbs energy which was closely related to the structure of the transferred ions, protonated amino acids.

关键词： micro-/nano-pipet, water/1,2-dichloroethane interface, facilitated ion transfer, cyclic voltammetry, amino acid.

EFFECT OF molecular WEIGHT OF PEO ON THE STRUCTURE AND PROPERTIES OF PDMAEMA/PEO HYDROGELS

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Chinese Journal of Polymer Science 2006年第1期24卷 35-40页

作者： Zhu-gen Liu Min Yi Mao-lin Zhai and hong-fei Ha department of applied chemistry and The Key Laboratory of Polymer chemistry and Physics of Ministry of Education,college of chemistry & molecular engineering,peking university,beijing 100871,china department of applied chemistry and The Key Laboratory of Polymer chemistry and Physics of Ministry of Education College of Chemistry & Molecular Engineering Peking University Beijing 100871 China

A new kind of binary hydrogels composed of poly（dimethylaminoethylmethacrylate）（PDMAEMA） and poly（ethylene oxide）（PEO） with varying weight average molecular weights （M^-w = 5 × 10^4, 1 × 10^5 and 2.5 × 10^6） were prepared by У-irradiation technology. The properties of PDMAEMA/PEO hydrogels obtained were evaluated in terms of gel fraction, gel strength, thermal characterization and swelling behavior. The gel strength and swelling degree of the hydrogels could be improved obviously after adding PEO into the PDMAEMA system, while the degree of improvement decreased with increasing M^-w of PEO. The temperature sensitivity of PDMAEMA/PEO was retained only in the sample with PEO of M^-w = 5 × 10^4, and the pH sensitivity was retained in samples with PEO of M^-w = 5 × 10^4 and 1 × 10^5. When DMAEMA/PEO mixtures containing PEO of M^-w = 5 × 10^4 were irradiated, the main reaction could be the cross-linking of DMAEMA, and the linear PEO molecular chains could penetrate into the cross-linked network of PDMAEMA. With increasing M^-w of PEO, some side reactions were induced, such as grafting of DMAEMA onto PEO molecules, the scission or cross-linking of PEO.

关键词： Poly(dimethylaminoethylmethacrylate) Poly(ethylene oxide) molecular weight Binary hydrogels Irradiation.

CONTROLLED RELEASE FROM PDMAEMA GELS PREPARED BY GAMMA RADIATION

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Chinese Journal of Polymer Science 2002年第5期20卷 409-412页

作者： Ning Liu Min Yi Shuang-ji Chen hong-fei Ha college of chemistry and molecular engineering peking university beijing 100871, china department of Biochemistry college of applied Arts and Science, beijing Union university beijing 100083. china college of chemistry and molecular engineering Peking University 北京 100871 department of Biochemistry College of Applied Arts and Science Beijing Union University 北京 100083

Poly(N,N-dimethylaminoethyl methacrylate) (polyDMAEMA) hydrogels prepared by gamma-irradiation showed obvious temperature-sensitivity in a temperature range of 38-40degreesC and pH-sensitivity at pH=2.5. They also showed electric response behavior although it was not typical. The hydrogels were used in controlled release at different pH, temperature, and electric voltage. The release rates of methylene blue (MB) from the gels at 52degreesC and pH=1.24 were faster than those at 20degreesC and pH=10.56, respectively. In addition, the release rate at a field voltage of 5.0 was also faster than that without electric field.

关键词： poly(N,N-dimethylaminoethyl methacrylate) environmental sensitivity hydrogel controlled release

SYNTHESIS AND CHARACTERIZATION OF STRUCTURALLY WELL-DEFINED POLYMER-INORGANIC HYBRID NANOPARTICLES VIA ATRP

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Chinese Journal of Polymer Science 2002年第3期20卷 261-267页

作者： Jie Bai Jie-bin Pang Kun-yuan Qiu Yen Wei department of Polymer Science & engineering college of chemistry & molecular engineering peking university beijing 100871, china department of chemistry Drexel university Philadelphia, PA 19104 USA department of Polymer Science & engineering College of Chemistry & Molecular Engineering Peking University 北京 100871 department of chemistry Drexel University 美国 Philadelphia PA 19104

Atom transfer radical polymerization (ATRP) using cuprous chloride/2,2'-bipyridine (bipy) was applied to graft polymerization of styrene on the surface of silica nanoparticles to synthesize polymer-inorganic hybrid nanoparticles, 2-(4Chloromethylphenyl) ethyltriethoxysilane (CTES) was immobilized on the surface of silica nanoparticles through condensation reaction of the silanol groups on silica with triethoxysilane group of CTES. Then ATRP of St was initiated by this surface-modified silica nanoparticles bearing benzyl chloride groups, and formed PSt graft chains on the surface of silica nanoparticles. The thickness of the graft chains increased with reaction time. End group analysis confirmed the occurrence of ATRP. Thermal analysis indicated that thermal stabilization of these resulting hybrid nanoparticles also increases with polymerization conversion. The results above show that this 'grafting from' reaction could be used for the preparation of polymer-inorganic hybrid nanoparticles with controlled structure of the polymer's end groups.

关键词： atom transfer radical polymerization polymer-inorganic hybrid nanoparticles 2-(4-chloromethylphenyl)ethyltriethoxysilane surface-modification

NEW OPTICALLY ACTIVE AROMATIC POLYIMIDES Ⅱ: SYNTHESIS AND PROPERTIES OF OPTICALLY ACTIVE AROMATIC POLYIMIDE BASED ON (R)-(+)-2, 2′-BIS (2-TRIFLUORO-4-AMINOPHENOXY)-1, 1′-BINAPHTHYL

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Chinese Journal of Polymer Science 1999年第1期17卷 87-90页

作者： Qi-ding Mi Yu Ma Lian-xun gao Meng-xian Ding Changchun Institute of applied chemistry, Chinese Academy of Sciences Changchun 130022, china department of chemistry, peking university, beijing 100871 中科院长春应用化学所吉林长春 130022 中科院长春应用化学所吉林长春

Optically active (R)-(+)-2, 2' -bis(2 -trifluoro-4 -aminophenoxy)- 1, 1' -binaphthyl was prepared from1, 1'-bi-2-naphthol. The optically active aromatic polyimide was also successfully synthesized. This newpolymer has good solubility, thermal stability etc. Its specific rotation was found to be +174°, and itschiroptical property was also studied.

关键词： Optical activity 1, 1′-Bi-2-naphthol, Polyimide

Biological decomposition of Na_2S_2O_3 into sulfur by a newly isolated facultative thermophilic alkaline desulphuricant strain

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Science china chemistry 2009年第2期52卷 226-230页

作者： ZHANG JianBin1,ZHANG Tong2,MA Kai2,ZHANG PengYan2,LI Qiang2 & WEI XiongHui1 1 department of applied chemistry,college of chemistry & molecular engineering,peking university,beijing 100190,china 2 college of Chemical engineering,Inner Mongolia university of Technology,Huhhot 010051,china department of applied chemistry College of Chemistry & Molecular Engineering Peking University Beijing China college of Chemical engineering Inner Mongolia University of Technology Huhhot China

A facultative thermophilic alkaline desulphuricant strain named GDJ-3 was isolated from neutral soils,enriched on sulfur synthetic medium,and detected in previous *** and chemotax-onomic analyses and 16s RNA gene sequencing showed that the strain was in good agreement with Alpha proteobacterium sp.(97%) and ochrobactrum sp.(98%).The regenerative processes of the solu-tion containing sulfur compounds(SCS) from the strain through an orthogonal test were investigated to get the optimum regenerative *** results showed that regenerative temperature,air flow,and stirring speed of the agitator were the main three variables influencing the regenerative processes of the *** optimum regenerative efficiency of the SCS from the strain was obtained when tem-perature,air flow,and stirring speed of the agitator were 318.2 K,3.0 L/min,and zero r/min,*** this condition,when the cell concentration of the strain was adjusted to 107/mL,the concentra-tions of Na2S2O3 and Na2S in the SCS decreased from 112.68 g/L to 96.88 g/L and from 0.87 g/L to 0.11 g/L in 9.5 ***,XRD spectrum shows that sulfur was formed in the regeneration *** results suggest that the strain has potential application to the regeneration of the industrial so-lution containing sulfur compounds.

关键词： bio-desulfurization thermophiles optimization biocomposition orthogonal test

DOPING LEVEL INCREASE OF POLY(3-METHYLTHIOPHENE)FILM DURING ELECTROCHEMICAL POLYMERIZATION PROCESS

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Chinese Journal of Polymer Science 2002年第5期20卷 425-430页

作者： Jing-kun Xu gao-quan Shi Feng-en Chen Xiao-yin hong department of chemistry and Bio-organic Phosphorous chemistry Laboratory Tsinghua university beijing 100084, china department of chemistry and Bio-organic Phosphorous chemistry Laboratory Tsinghua University 北京 100084

The Raman spectra of poly(3-methylthiophene) (PMeT) films with different thicknesses, which have been electrochemically deposited on a flat stainless steel electrode surface by direct oxidation of 3-methylthiophene in boron trifluoride diethyl etherate (BFEE) at a constant applied potential of 1.38 V (versus SCE), have been investigated by excitation with a 633-nm laser beam. The spectroscopic results demonstrated that the doping level of PMeT film was increasing during film growth. This finding was also confirmed by electrochemical examination. Moreover, the Raman bands assigned to radical cations and dications in doped PMeT films were found approximately at 1420 and 1400 cm(-1), respectively. Radical cations and dications coexist on the backbone of PMeT as conductive species and their concentrations increase with the increase of doping level. Successive cyclic voltammetry was proved to be an effective approach to improving the doping level of as-grown thin compact PMeT film.

关键词： poly(3-methylthiophene) Raman spectra doping level radical cations dications

CRYSTALLIZATION KINETICS OF HOMOGENEOUS AND HETEROGENEOUS LLDPE

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Chinese Journal of Polymer Science 2002年第4期20卷 339-345页

作者： hong-xiang Teng Wen-hong Tang Yi Shi Xi-gao Jin State Key Laboratory of Polymer Physics and chemistry Center for molecular Science, Institute of chemistry Chinese Academy of Sciences beijing 100080 china department of chemistry Jilin university Changchun 130023, china Center for molecular Science Institute of Chemistry Chinese Academy of Sciences State Key Laboratory of Polymer Physics and Chemistry 北京 100080 department of chemistry Jilin University Changchun 130023

Based on thermal analysis, the isothermal and nonisothemal crystallization kinetics of Ziegler-Natta catalyzed linear low density polyethylene (Z-N LLDPE) and metallocene catalyzed LLDPE (m-LLDPE) were studied. Treating the results with the Avrami equation and the Ozawa equation, the crystallization constant Igk and the Avrami exponent n were obtained. Some other crystallization parameters were also discussed. According to the different characteristics of the chain structures of Z-N LLDPE and metallocene LLDPE, their crystallization behaviors were analyzed. It is indicated that the homogeneity and heterogeneity of the two polymers act in different way during the crystallization process of polymers, including the nucleation and the growth of crystals under various conditions.

关键词： crystallization kinetics homogeneity heterogeneity LLDPE