结构可控的聚合物长短刷接枝纳米粒子

Bimodal Polymer-grafted Nanoparticles with Precisely Controlled Structures

通过RAFT聚合制备了一系列窄分子量分布的聚(γ-甲基丙烯酰氧基丙基三乙氧基硅烷)(PTEPM)-b-聚甲基丙烯酸甲酯(PMMA)嵌段共聚物和PTEPM、PMMA低聚物.将具有不同PMMA分子量的2种PTEPM-b-PMMA共聚物与低聚物PMMA或PTEPM进行共组装(微相分离),形成片、柱、球等不同PTEPM相区结构.采用盐酸气氛处理,PTEPM相区水解交联形成倍半硅氧烷SiO1.5内核,分离纯化得到聚合物长短刷接枝纳米粒子.使用这种相分离-交联-分散制备方法,调节嵌段共聚物分子结构和三组分比例,可实现聚合物接枝纳米粒子内核形状和尺寸、接枝密度、长短刷比例、长刷长度的精确调控.这些纳米粒子是研究聚合物纳米复合材料结构-性能关系的理想模型体系.

A series of poly(3-(triethoxysilyl)propyl methacrylate)(PTEPM)oligomers(oT),polymethylmethacrylate(PMMA)oligomers(oM),and block copolymers of PTEPM-b-PMMA with narrow molecular weight distributions were synthesized using RAFT polymerization.Two PTEPM-b-PMMA copolymers with the PMMA blocks of different molecular weights were co-assembled with the oligomers of PMMA or PTEPM to form various ordered nanoscale structures,such as lamellae,cylinders,and spheres.PTEPM block could be crosslinked to form silsesquioxane core(i.e.,SiO_(1.5)),when the obtained co-assembly materials were immersed in hydrochloric acid atmosphere.After appropriate separation and purification,the bimodal polymer grafted nanoparticles(PGNPs)with different microstructures could be prepared.Using this assembling-crosslinking-dispersing(ACD)method and adjusting the molecular structure of block copolymer and the ratio of the three components(PTEPM-b-PMMA,oT,and oM),the structural parameters of bimodal PGNPs,including the shape and size of core,grafting density,molar ratio between long and short brushes,and length of long brushes,could be precisely controlled.By adjusting the proportions of two block copolymers with the PMMA blocks of different molecular weights and the amounts of oMs,bimodal PGNPs with different molar ratios of long and short brushes could be prepared.By adjusting the molecular weight of the long brush and the amounts of oM,bimodal PGNPs with different lengths of long brushes were obtained.By adjusting the amounts of oM and oT,bimodal PGNPs with the same core shape but different sizes were obtained.By adjusting the amounts of oM,bimodal PGNPs with the same core weight but different shapes(cylindrical or spherical)were obtained.These nanoparticles are ideal model models for studying the relationship between the microstructures and properties of polymer nanocomposites.