两性离子单体在低温下的立构规整自由基聚合.rar

摘要：在0-100℃温度范围内，在不同反应温度下进行磺酸甜菜碱类单体，N，N-二甲基-N-甲基丙烯酰氧乙基-N-丙基磺酸铵(DMAPS)和N，N-二甲基-N-甲基丙烯酰氧乙基-N-丁基磺酸铵(DMABS)，普通自由基聚合反应，采用质子核磁共振(1H NMR)测得聚合物的立构规整度，结果表明：聚合物的间同立构规整度随反应温度的降低而增大。产生这一现象的原因是，磺酸甜菜碱类单体是两性离子单体，由于电荷作用和单体侧基的位阻效应，使得在聚合过程中更容易形成间同立构。根据Bernoulli模型估算出全同和间同增长的活化焓差ΔH为13.72kJ/mol和活化熵差ΔS为33.66J/(K·mol)，这说明生成间同立构是热力学有利的。在反应温度不变的情况下，在不同的NaCl浓度的溶液中进行磺酸甜菜碱类单体普通自由基聚合，质子核磁共振(1H NMR)结果表明：当反应温度不变时，反应液中单价态离子浓度越低，聚合物间同立构规整度越高。

关键词：两性离子单体 立构规整度 磺酸甜菜碱单体 核磁共振氢谱

Abstract：In the temperature range of 0-100℃, sulfobetaine monomers, N,N-dimethyl-N-(methacryloyloxy) ethyl ammonium propyl sulfonate(DMAPS) and N,N-dimethyl-N-(methacryloyloxy) ethyl ammonium butane sulfonate(DMABS), carried out free radical polymerization reaction under different reaction temperatures. Proton nuclear magnetic resonance (1H NMR) measured stereoregularity of polymers, results show that: syndiotactic stereoregularity of polymers with decreasing reaction temperature with increasing. The reason for this phenomenon is, sulfo-betaine monomers are zwitterionic monomers, due to the bulky hindrance and electrostatic interaction, resulting in the polymerization process is easier to form syndiotactic. According to the Bernoulli model, to estimate isotctic and syndiotactic growth activation enthalpy difference ΔH 13.72kJ/mol and activation entropy difference ΔS 33.66J/(K·mol), which generates syndiotaxy is thermodynamically favorable. In response to temperature unchanged, the free radical polymerization of sulfobetaine monomers in different concentration of NaCl solution. The results of proton nuclear magnetic resonance (1H NMR) show that: when the reaction temperature is constant, the concentration of monovalent ions in the reaction solution is low, the syndiotactic stereoregularity of polymers higher. 

Key words: zwitterionic monomer, stereoregularity, sulfobetaine monomer, 1H NMR