光敏感三臂星形聚[甲基丙烯酸2-(二甲氨基)乙酯]的合成及其光敏性能研究

以香豆素为光敏感基元,通过多步反应制备了三臂ATRP引发剂C-Br3,然后以CuBr/PMDETA为催化体系、甲基丙烯酸2-(二甲氨基)乙酯(DMAEMA)为单体,ATRP聚合法制备了三臂星形聚合物C-(PDMAEMA)3.用傅里叶变换红外光谱仪(FTIR)、紫外-可见光分光光度计(UV-Vis)和核磁共振仪(1H-NMR)等对C-Br3及聚合物进行了结构表征.研究表明,该三臂星形聚合物可在水中直接形成胶束,且该聚合物可在365和254 nm交替紫外光照下发生可逆光二聚反应.纳米粒度跟踪显示,光照前其胶束粒径为(87.7±27.8)nm、呈高斯分布;而在365和254 nm光反应后,聚合物胶束粒径大小与分布仅发生微弱变化.这可能是因为在光二聚反应前后,聚合物的双亲结构变化微弱所致.

SYNTHESIS AND PROPERTIES OF PHOTO-SENSITIVE THREE-ARMED STAR POLY[2-(DIMETHYLAMINO)ETHYL METHACRYLATE]

A three armed ATRP initiator(C-Br3) containing photo-sensitive coumarin group was designed and synthesized in a multi-step reation,which was used to prepare amphiphilic photo-sensitive star polymer C-(PDMAEMA)3 by ATRP with 2-(dimethylamino)ethyl methacrylate(DMAEMA) as hydrophilic monomer and CuBr/PMDETA as the catalytic system.The structures of C-Br3 and C-(PDMAEMA)3 were confirmed by FTIR,GPC and1H-NMR.It was found that the star polymer could form polymer micelles in aqueous solutions.And the coumarin center group of the star polymer can be reversibly photo-dimerized upon 365 and 254 nm irradiation.However,the hydrodynamic size analysis determined by Malvern Zetasizer Nano-ZS showed that the polymer micelles had a gaussian distribution(87.7 ± 27.8) nm of size before photo-crosslinking,and it changed slightly upon 365 and 254 nm irradiations.The reason for this slight size changes maybe that there were very minor changes in the polymeric amphiphilic structure before and after photo-reactions.