PDMS-b-PEO两亲性嵌段共聚物的合成及溶液性质

通过正丁基锂(n-BuLi)引发的六甲基环三硅氧烷(D3)阴离子开环聚合以及单硅氢封端聚二甲基硅氧烷(PDMS)与烯丙基聚氧乙烯醚(PEO)的硅氢加成反应, 合成得到了一系列分子量分布窄的PDMS-b-PEO两亲性嵌段共聚物. 利用凝胶渗透色谱(GPC)、傅里叶变换红外(FTIR)光谱、氢核磁共振谱(1H-NMR)表征了嵌段共聚物的结构组成. 通过表面张力仪测定得到了不同结构嵌段共聚物的平衡表面张力及临界胶束浓度(cmc). 结果显示, 该系列嵌段共聚物的cmc值不仅受到憎水性嵌段的影响, 同时也受嵌段共聚物的体积效应以及嵌段共聚物的几何形状(即嵌段共聚物各嵌段的比例)的影响, PDMS-b-PEO两嵌段共聚物的cmc值表现出了随憎水嵌段增加而相应增加的趋势. 通过透射电子显微镜(TEM)表征发现, PDMS-b-PEO嵌段共聚物在选择性溶剂水中会自组装形成球状、棒状以及囊泡状的聚集体.

Synthesis and Solution Properties of PDMS-b-PEO Amphiphilic Diblock Copolymers

A series of well-defined polydimethylsiloxane-b-poly(ethylene oxide) (PDMS-b-PEO)  amphiphilic diblock copolymers were synthesized by the combined use of anionic ring-opening polymerization of hexamethylcyclotrisioxane (D3) with n-butyllithium as the initiator and hydrosilation between Si—H terminated PDMS and ally terminated PEO homopolymers. The structures of PDMS and amphiphilic diblock copolymers PDMS-b-PEO were verified by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy analyses. The diblock copolymers showed monomodal gel permeation chromatography (GPC) traces which indicated narrow molecular weight distributions (MWDs). Additionally, the solution properties of these diblock copolymers were investigated using tensiometry and transmission electron microscopy (TEM) . The equilibriumsurface tension γ and critical micelle concentration (cmc) of PDMS-b-PEO in an aqueous solution was also investigated. Interestingly, the cmc increases as the length of the hydrophobic chain increases. Transmission electron microscopy showed that PDMS-b-PEO diblock copolymers in the aqueous solution self-assembled into various morphologies including spheres, rods, and vesicle aggregates.