【作者】 张友稳；

【导师】 杨万泰；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2010， 硕士

【摘要】 空心微球具有密度较低、比表面积较高、渗透性好等特点,内部空心结构可以容纳较多的物质,这种微观结构使其作为功能材料在化妆品、涂料、印刷、造纸、药物缓释及催化剂载体等领域有着广泛应用,聚合物空心球作为其中的一大类,同样具有上述所有的性质。本文采用一种新的分散聚合的方法制备聚苯乙烯纳米尺寸的空心球,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PSt核-P(St-DVB)壳(壳交联)结构微球。进一步,使用PSt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的反应条件：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增大,内核不易溶出；增大起始单体浓度,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,得到蜂窝状空球；交联剂用量增加,所得空心球的刚度和壁厚增加。微球的结构规整、壁厚均匀,直径约为800nm,通过调整单体浓度、引发剂的量,DVB的加入时间、DVB的量、溶解时间等因素可以影响空心微球的壳层厚度、均匀度、硬度等,其中单体浓度和DVB的加入时间影响最大。与传统的模板法相比,本方法不需要单独的步骤制备模板,反应具有连续性,同时模板易去除,具有操作简单,球体厚度可控等优点。更多还原

【Abstract】 In this paper, monodisperse core (PSt)-shell (cross-linked P(St-DVB)) microspheres were prepared firstly by a two-stage dispersion polymerization in which DVB was charged into reaction system after monomer conversion high up to 80%. The cross-linking mainly took place at the surface of PS particles to form shell layer. Subsequently, hollow particles composed of cross-linked P(St-DVB) were prepared by dealing the core-shell microspheres with a solvent of THF in which the core polymer was dissolved and removed.The morphology of the generated core-shell or hollow structures was observed by SEM and TEM. The influences of some parameters such as the initiator concentration, monomer content and crosslinker amount applied in the dispersion polymerization on the morphology of final hollow particles were investigated. The results indicated that perfect hollow particles could not be readily produced if greater concentration of initiator was used in the first dispersion polymerization, owning to the somewhat difficulty in removing the core polymer with high molecular weight. High monomer content presented in the polymerization could lead to the less rigidity of the final hollow particles, while the low monomer content could bring about densely crosslinked shell, and thus allow some core polymer remained in THF treatment, resulting in the formation of honeycomb particles. Increasing the amount of crosslinker employed in dispersion polymerization, hollow particles with proper thickness and rigidity were fabricated finally.更多还原