醇/水介质对PEG大分子单体与BMA分散共聚反应的影响

通过端基反应法合成了苯乙烯单封端的聚乙二醇(St- PEG)大分子单体,使其与甲基丙烯酸丁酯(BMA)在乙醇 水混合介质中进行分散共聚,得到了聚乙二醇接枝的聚甲基丙烯酸丁酯(PBMA- g -PEG)高分子微球.PBMA- g -PEG共聚物的亲溶剂 疏溶剂平衡将影响微球的形成,反应结束时,体系随BMA浓度和介质中水含量的变化呈现出4种不同的状态,透明清液、乳液、伴有沉淀或凝胶的乳液和凝胶.用透射电子显微镜(TEM)和激光光散射(LLS)对乳液体系的粒径及其形态进行了表征,表明所得接枝高分子微球形态规整具有较好的单分散性.通过控制介质中水的含量和BMA的浓度可得粒径在4 0～5 0 0nm范围的PBMA -g -PEG微球.

THE EFFECT OF ETHANOL/WATER MEDIUM ON THE DISPERSION COPOLYMERATION OF BUTYL METHACRYLATE WITH POLY(ETHYLENE GLYCOL) MACROMONOMER

Polymeric nanospheres consisting of poly(butyl methacrylate) (PBMA) cor es and poly(ethylene glycol) (PEG) branches on their surfaces were prepared by f ree radical copolymerization of butyl methacrylate (BMA) and PEG macromonomer wi th a p-vinylbenzyl end group in ethanol/water mixed medium.It was found tha t th e solvophilic/solvophobic balance between the copolymers and mediums had great e ffect on the formation of nanospheres.The obtained polymer dispersion exhibited four kinds of states:clear solution,particle dispersion (milky solution),milky s olution with gel/precipitation and gel with varying the BMA concentration and water content in the mixed medium.The particle size and morpho log y of obtained nanospheres were characterized by the transmission electron micros copy and laser lighter scattering.The nearly monodispersed nanospheres with par ticle sizes from 40 nm to 500 nm could be obtained by controlling the BMA conce ntration and water content in mixed medium.