利用原子转移自由基聚合(ATRP)方法合成了组成递变的2-甲基-2-丙烯酸-2-(2-甲氧基乙氧基)乙酯(MEO2MA)与寡聚乙二醇甲醚甲基丙烯酸酯(OEGMA)共聚物P(MEO2MA-co-OEGMA). 核磁共振氢谱(1HNMR)和凝胶渗透色谱(GPC)表征了聚合物的结构、分子量及其分布. 通过测定透光率、粘度、激光粒度分析了共聚物组成对共聚物低临界溶解温度(LCST)的影响, 考察了共聚物组成、浓度、盐浓度、盐种类、温度对其溶液相行为的影响. 结果表明: 所合成的共聚物具有温度敏感性, 其LCST 可以通过合成时共聚单体MEO2MA与OEGMA投料比的改变来调控, 随着OEGMA量的增加共聚物的LCST升高, 共聚物溶液浓度升高其LCST减小, 随盐溶液浓度的增大共聚物的LCST降低, 共聚物的LCST降低主要受盐溶液中阴离子价数的影响; HCl的引入使共聚物水溶液的LCST降低; NaOH的引入使共聚物水溶液的LCST升高.
Temperature-responsive P(MEO2MA-co-OEGMA) copolymers of 2-(2-methoxyethoxy) ethyl methacrylate (MEO2MA) and oligo(ethylene glycol) methacrylate (OEGMA) were synthesized via atom transfer radical polymerization (ATRP) in ethanol using CuCl/2,2'-bipyridyl (bpy) as the catalyst system and ethyl-2-bromopropionate (EBP) as an initiator. The synthesized copolymers were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR) and gel permeation chromatography (GPC). Copolymer temperature sensitivities in aqueous solution were investigated by measurements of optical transmittance and viscosity as well as laser particle size analysis. The effects of various parameters on the phase transition temperatures of aqueous copolymer solutions were examined, including OEGMA content, solution concentration, and the concentrations and species of added salts. Results showed that the copolymers demonstrated temperature sensitivity; the lowest critical solution temperature (LCST) increased both with increasing OEGMA content and decreasing solution concentration. Copolymer LCST values could also be controlled by adjusting the mole fractions of MEO2MA and OEGMA. It was additionally observed that LCST values decreased as the salt concentration and anion valence increased. The addition of acid or base also affected the LCST of the copolymer solutions; addition of HCl decreased the LCST while addition of NaOH resulted in an increase.