热分析技术研究疏水缔合微区对含氟丙烯酸酯共聚物凝胶中水状态的影响  

THERMAL ANALYSIS OF THE EFFECT OF HYDROPHOBIC MICRODOMAINS ON THE WATER STATE OF 2-( N-ETHYLPERFLUOROOCTANEUS-LFOAMIDO)ETHYL METHACRYLATE MODIFIED GELS

作　　者：田琴[1] 赵喜安[1] 唐小真[1] 章云祥[2] 

机构地区：[1]上海交通大学化学化工学院,上海200240 [2]中国科学院上海有机化学研究所,上海200032

出　　处：《高分子学报》2003年第2期180-185,共6页Acta Polymerica Sinica

基　　金：国家自然科学基金资助项目 (基金号 5 9973 0 2 5 )

摘　　要：丙烯酸 (AA)与不同含量的 2 (N 乙基全氟辛烷基磺酰胺 )乙基甲基丙烯酸酯 (FMA)在叔丁醇中进行自由基共聚 ,合成了一系列疏水改性共聚物凝胶 .用示差扫描量热法 (DSC) ,热失重分析 (TGA)研究了含氟疏水改性凝胶中水的状态 ,证明FMA改性凝胶中存在 3种状态的水 ,即不可冻结水 ,可冻结结合水和自由水 .对于未改性凝胶和FMA含量为 1mol%的疏水改性凝胶 ,在凝胶中水含量分别低于 0 60 9mol%和 0 698mol%时 ,DSC升温曲线上观察不到熔融峰 ,说明凝胶中存在不可冻结水 .提出计算凝胶中 3种状态的水含量和熔融焓的理论假设 .计算出FMA含量为 1mol%的疏水改性凝胶中自由水和可冻结结合水的摩尔熔融焓分别为75 89 0 3和 6864 0 6J mol.计算结果表明疏水改性后 ,单位聚合物单元上结合的可冻结水数目 (n1 )和非冻结水的数目 (n0 )Recently, some attention has been paid to hydrophobically modified gels (HM-gels) with a small number of hydrocarbon side groups in their chain backbones. However, few papers can be retrieved for fluorocarbon-modified gels although fluorocarbon groups show the strong ability of hydrophobic association than hydrocarbon ones. In HM-gels, the association of hydrophobic side groups affects directly the state and amount of water. Therefore it is necessary to investigate the states of water in fluorocarbon-modified gels in order to understand the relationship between their hydrophobic microstructure and macroscopic properties. In this paper, a series of hydrophobically modified poly(acrylic acid) (HM-PAA) gels were prepared by radical copolymerization of acrylic acid (AA) and a small amount of hydrophobical comonomers, 2-(N-ethylperfluorooctanesulfoamido) ethyl methacrylate (FMA) in tert butanol. The effects of hydrophobic modification on water states of gels were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). For HM-PAA gel with FMA content of 1%, no melting peaks were observed with water content (W-c) lower than 0.698 mol % and two melting peaks appeared with W-c higher than 0.698 mol % in DSC heating curves, which proved the existence of three states of water molecules, that is,free water, non-freezing water and freezing bound water in FMA-modified gels. A method for calculating the melting enthalpy of different states of water in gels the numbers of non-freezing and freezing bound water molecules associated with a polymer unit, n(0) and n(1) was brought forward. The numbers of non-freezing and freezing bound water molecules associated with a polymer unit, n(0) and n(1), increased after hydrophobic modification. For the gel sample PAA-FMA1% the melting enthalpies of freezing bound water and free water were measured to be 7589.03 and 6864.06 J/mol, respectively.

关 键 词：热分析技术 疏水缔合 氟丙烯酸酯共聚物 水凝胶 水状态 热力学 

分 类 号：O657.99[理学—分析化学]