Xu Yiting, Cao Jie, Li Qi, Li Jilu, He Kaiwei, Shen Tong, Liu Xinyu, Yuan Conghui, Zeng Birong, Dai Lizong
Fujian Provincial Key Laboratory of Fire Retardant Materials, Xiamen University Xiamen 361005 People's Republic of China
RSC Adv. 2018 Apr 30;8(29):16103-16113. doi: 10.1039/c8ra01660g. eCollection 2018 Apr 27.
A series of novel azobenzene-based amphiphilic random copolymers P(POSSMA--AZOMA--DMAEMA) were synthesized reversible addition-fragmentation chain transfer (RAFT) polymerization. A light and reduction dual-responsive azo group, pH-responsive tertiary amine group and super hydrophobic POSS moiety were incorporated into the polymer chain to generate multi-stimuli-responsiveness. Self-assembly of these amphiphilic copolymers led to the formation of spherical micelles in aqueous solution. The light, pH and reduction responsive properties of the micelles were investigated systematically by DLS, TEM, UV-vis, FTIR and NMR. The azo groups can undergo - isomerization under UV light irradiation, thus causing a diameter change of the micelles. Owing to the large proportion of tertiary amine groups in amphiphiles, these micelles showed sensitive pH-response behavior. The hydrophobic azo pendant in the polymer chain completely reduced to a more hydrophilic substituted aniline in a reductive environment, resulting in the increase of overall hydrophilicity of amphiphiles and the disassembly of polymeric micelles. Owing to these multi-stimuli-responses, the polymeric micelles showed rapid and efficient release properties of hydrophobic molecules in response to pH and reductive stimuli.
通过可逆加成-断裂链转移（RAFT）聚合反应合成了一系列新型的基于偶氮苯的两亲性无规共聚物P（POSSMA-AZOMA-DMAEMA）。聚合物链中引入了光和还原双重响应的偶氮基团、pH响应的叔胺基团以及超疏水的POSS部分，以产生多重刺激响应性。这些两亲性共聚物的自组装导致在水溶液中形成球形胶束。通过动态光散射（DLS）、透射电子显微镜（TEM）、紫外可见光谱（UV-vis）、傅里叶变换红外光谱（FTIR）和核磁共振（NMR）系统地研究了胶束的光、pH和还原响应特性。偶氮基团在紫外光照射下可发生顺反异构化，从而导致胶束直径发生变化。由于两亲物中叔胺基团比例较大，这些胶束表现出敏感的pH响应行为。聚合物链中的疏水偶氮侧基在还原环境中完全还原为更亲水的取代苯胺，导致两亲物整体亲水性增加，聚合物胶束解体。由于这些多重刺激响应，聚合物胶束在pH和还原刺激下表现出对疏水分子的快速高效释放特性。
