单分散磁性P(St/BA/MAA)微球的制备

在共沉淀法合成超细磁流体的基础上 ,以苯乙烯 (St)、丙烯酸丁酯 (BA)和甲基丙烯酸 (MAA)为共聚单体 ,在不同的介质体系中采用无皂乳液聚合法制备了单分散 ,粒径范围为 80～ 2 30nm的磁性P(St BA MAA)微球 .详细探讨了介质极性、磁流体中表面活性剂含量对磁性高分子微球粒径和单分散性的影响 .实验结果表明 ,在一定范围内随介质极性降低 ,磁性高分子微球的单分散性提高 ,随表面活性剂用量增加 ,单分散性变差 .总体来看 ,磁性高分子微球的单分散性与其表面静电斥力密切相关 ,过大或过小的静电斥力均会导致磁性高分子微球单分散性的降低 .

PREPARATION OF MONODISPERSE MAGNETIC P(ST/BA/MAA) MICROSPHERES

Monodispersity is one of the important characteristics of magnetic polymer microspheres.In this paper,monodisperse magnetic poly(styrene/butyl acrylate/methacrylic acid) P(St/BA/MAA)] microspheres with the size ranging from 80 to 230 nm,were prepared by emulsifier\|free emulsion polymerization in the mixture of water and polar solvent,such as acetone,ethanol or methanol,in the presence of ferrofluid prepared by a co\|precipitation method.The effects of the medium polarity and the surfactant content in ferrofluid on the particle size and monodispersity of magnetic P(St/BA/MAA) microspheres were discussed in detail.The results showed that the electrostatic repulsion between microspheres and radicals had a geat effect on the monodispersity of magnetic micropsheres.Proper repulsion benefited the monodispersity,but the higher or lower repulsion would lead to the decrease in monodispersity.Moreover,the results revealed that some features of emulsifier\|free emulsion polymerization in the presence of ferrofluid was analogous to that of conventional emulsifier\|free emulsion polymerization.