大分子引发剂和三嵌段聚合物的表征.DOC

CO2/N2可逆单层囊泡-网状结构转变研究敬显武，黄志宇*，鲁红升 (成都，610500)摘要：以聚乙二醇000与α-溴代异丁酰溴进行酯化反应得到大分子引发剂，使用原子转移自由基聚合法合成了对称三嵌段且聚合度相等的聚甲基丙烯酸二甲胺乙酯-聚乙二醇-聚甲基丙烯酸二甲胺乙酯(PDM165-PEG165-PDM165)。以pH、电导率证明了聚合物溶液的CO2/N2循环可逆性，聚合物溶液中通入CO2后5min内pH值即从7.74下降至5.47溶液电导率从0.176 mS/cm迅速上升0.405 mS/cm；继而向溶液中通入N2，经过30 min后，pH值恢复至初始的7.74电导率至初始值0.177 mS/cm冷冻透射电镜观察得知聚合物在水中可自组装形成单层囊泡通入CO2后，叔胺被质子化，囊泡解离形成网状结构导致溶液黏度(s上升(s；叔胺质子化由证明2.3，2.7，4.1 ppm向低场移动至2.8，3.24.3 ppm。 关键词：，嵌段聚合物，单层囊泡，质子化 中图分类号： 文献标识码：A CO2/N2 Switchable Unilamellar Vesicle-Network Structure Transition Abstract: acroinitiator PEG6000-Br, was synthesized by esterification reaction of PEG6000 and α-Bromoisobutyryl bromide. By using ATRP method, a symmetrical triblock polymer with the same degree of polymerization, poly(2-(Dimethylamino)ethyl methacrylate)-PEG-poly(2-(Dimethylamino)ethyl methacrylate) (PDM165-PEG165-PDM165), was synthesized. The structures were characterized by FT IR and 1H NMR. The CO2/N2 switchability was proved by pH and conductivity, after 5 min of bubbling CO2, pH decreased from 7.74 to 5.47 and the conductivity increased from 0.176 mS/cm to 0.405 mS/cm rapidly. Then, after 30 min of bubbling N2, the pH recovered to the initial 7.74 and the conductivity decreased to the initial value of 0.177 mS/cm smoothly. The self-assembled unilamellar vesicles-network transition was observed by cryo-TEM, thus result in enhancement of viscosity increase from 3 mPa(s to 12 mPa(s. The key mechanism of these changes is protonation of tertiary amine groups in PDM blocks and was proved by 1H NMR, the chemical shifts of H near N atom downfield from 2.3, 2.7, 4.1 ppm to 2.8, 3.2, 4.3 ppm, respectively. Keywords: ATRP, block polymer, unilamellar vesicle, protonation 自从原子转移自由基聚合技术发现以来，嵌段聚合物的合成变得简单可行[1-3] 近年来，各种嵌段聚合物的自组装形态，如囊泡球形、棒状、蠕虫状胶束甚至Janus胶束已被大量报道[4-6]特别聚合物具有优良的可设计性，耐用性，以及不需要使用有机溶剂等优点，[7, 8]。 近年来，刺激响应型材料得到了广泛关注，常见的刺激种类有pH、光、温度、电压、氧化/还原剂[9-13][14]。由于CO2的天然低毒便宜易得等优点，引起了人们的注意。Yuan课题组合成了嵌段聚合物，在通入CO2，囊泡壁，可以使药物选择性透过及分离[15]合成了PDEAEMA-b-PNIPAM，以CO2和温度作为刺激物，聚合物可在