星型三杂臂共聚物的合成及其自组装性能研究

Synthesis and Self-assembly Behaviors of the ABC Miktoarm Star Terpolymer

通过将点击化学,原子转移自由基聚合与阳离子开环聚合相结合,合成了一种含亲水性聚乙二醇(PEG),疏水性聚四氢呋喃(PTHF)和环境响应性聚甲基丙烯酸N,N-二甲氨基乙酯(PDMA)的ABC星型杂臂聚合物MPEG-PTHF(-PDMA).通过FTIR、1H-NMR和凝胶渗透色谱/多角度激光光散射联用(SEC/MALLS)对其结构进行了表征.通过激光粒度仪和透射电子显微镜测试,并研究其在溶液中的自组装行为,分别在pH为5.0、7.4和9.5的缓冲溶液中测试了这种星型三元共聚物自组装性能,其可表现出温度响应性.

The ABC miktoarm star terpolymer MPEG-PTHF（-PDMA） was synthesized by the combination of click chemistry, atom transfer radical polymerization （ATRP） and cationic ring opening polymerization （ CROP ）. A block copolymer of poly（ethylene glycol） （ PEG ） and poly（N,N-dimethylaminoethy] methacrylate） （PDMA） which bears an azido at diblock junction （MPEG-N3 （-PDMA）） was first prepared by atom transfer radical polymerization. Then, an alkynyl-terminated narrow distributed polytetrahydrofuran （PTHF-Alk） was synthesized as another building block via cationic ring opening polymerization. The welldefined ABC miktoarm star shaped terpolymer was afforded by clicking MPEG-N3 （-PDMA） onto the chain end of PTHF-Alk. The structure of the star terpolymer was characterized by the FTIR, NMR and SEC/MALLS. The self-assembly behavior of the polymer were investigated by dynamic light scattering （DLS） and transmission electron microscopy （TEM）. This star shaped terpolymer consists of a hydrophobic PTHF chain, a bydrophiphilic PEG chain and another stimuli-responsive PDMA chain. It can self-assemble into micelles with different sizes and morphologies at various pH values, such as 5.0,7.4 and 9.5. The micellar size also exhibits temperature-dependence at pH 7.4 and 9.5. The variation of size and morphology of the micelles with the solution pH and temperature is ascribed to the pH- and thermo-responsive properties of the PDMA block.