论文部分内容阅读
以聚乙二醇6000与α-溴代异丁酰溴进行酯化反应得到大分子引发剂PEG6000-Br,使用原子转移自由基聚合(ATRP)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(PDM_(165)-PEG_(165)-PDM_(165))。利用FTIR和~1HNMR对其结构进行了表征。以p H、电导率测试证明了聚合物溶液的CO_2/N_2循环可逆性,聚合物溶液中通入CO_2后,5 min内,溶液p H值即从7.74下降至5.47,溶液电导率从0.176 m S/cm迅速上升至0.405 m S/cm;继而向溶液中通入N_2,经过30 min后,溶液的p H值和电导率都恢复到初始值。冷冻透射电镜(Cryo-TEM)观察得知,聚合物在水中可自组装形成单层囊泡,通入CO_2后,叔胺被质子化,囊泡解离形成网状结构,导致溶液黏度从3 m Pa·s上升至12 m Pa·s,叔胺质子化由~1HNMR证明,N原子附近的氢位移从δ2.3、2.7、4.1向低场分别移动至δ2.8、3.2、4.3。
The macromolecular initiator PEG6000-Br was obtained by esterification reaction of polyethylene glycol 6000 with α-bromoisobutyryl bromide. A symmetric triblock copolymer with the same degree of polymerization was synthesized by atom transfer radical polymerization (ATRP) Dimethylaminoethyl methacrylate-polyethylene glycol-polyethylmethacrylate (PDM_ (165) -PEG_ (165) -PDM_ (165)). Its structure was characterized by FTIR and ~ 1HNMR. With p H and conductivity tests, the reversibility of the CO 2 / N 2 cycle in the polymer solution was proved. The p H value decreased from 7.74 to 5.47 within 5 min after the polymer solution was introduced into CO 2. The conductivity of the solution increased from 0.176 m S / cm rapidly rose to 0.405 m S / cm; then N 2 was introduced into the solution, and after 30 min, the p H value and conductivity of the solution returned to their initial values. Cryo-TEM observation revealed that the polymer self-assembled into water in the formation of single-layer vesicles, access to CO_2, the tertiary amine is protonated, the vesicles dissociated to form a network structure, resulting in solution viscosity from 3 mPa · s increased to 12 mPa · s. The protonation of tertiary amine was confirmed by ~ 1HNMR. The hydrogen shift in the vicinity of the N atom shifted from δ2.3, 2.7 and 4.1 to δ2.8, 3.2 and 4.3 respectively.