分散聚合两步法制备壳交联聚合物微球及自模板制备空心球

采用分散聚合两步加料法,在单体苯乙烯(St)转化率达80%以上时加入交联剂二乙烯基苯(DVB),以未交联内核自身为模板,制备了PS核-P(St-DVB)壳(壳交联)结构微球。然后使用PS的良溶剂THF将未交联内核溶出后,制得了结构规整的空心聚合物微球。采用扫描电镜(SEM)及透射电镜(TEM)观察了所得核-壳、空心球的形貌,探讨了核-壳聚合物微球制备过程引发剂用量、单体浓度及交联剂用量对最终所得空心球形貌的影响。结果表明:增大引发剂用量,微球内核聚合物的分子量减小,内核容易溶出;增大起始单体浓度,壳层交联剂含量相对减小,所得空心球易破裂,刚度下降;单体浓度过低可使交联层致密,不利于内核聚合物溶出,得到蜂窝状空心球;交联剂用量增加,所得空心球的刚度和壁厚增加。

Preparation of core-shell and hollow polymer particles by two-stage dispersion polymerization

Monodisperse polystyrene (PSt) core-cross-linked poly(styrene-divinylbenzene) (P(St-DVB) shell microspheres have prepared by a two-stage dispersion polymerization in which DVB was charged into the reaction system after St monomer conversion reached as high as 80%. The cross-linking mainly took place at the surface. Subsequently, hollow particles composed of the cross-linked P(St-DVB) were prepared by treating the core-shell microspheres with THF in which the core PSt polymer dissolved and was removed. The morphology of the hollow particles was observed by SEM and TEM. The influence of varying the synthesis parameters was investigated. The results indicated that perfect hollow particles could be readily produced if appropriate concentrations of initiator and monomer were used in the first dispersion polymerization. By increasing the amount of the crosslinker employed in the dispersion polymerization, hollow particles with suitable thickness and rigidity can be fabricated. 