在单分散聚苯乙烯种子微球合成基础上,通过两步溶胀法以及傅克(Friedel-Crafts)烷基化反应,制备内外贯通的多级孔聚苯乙烯微球,对微球的化学结构、形貌结构、粒径及分布、孔尺寸及分布等进行研究。结果显示,当单体苯乙烯浓度为15%,以乙...在单分散聚苯乙烯种子微球合成基础上,通过两步溶胀法以及傅克(Friedel-Crafts)烷基化反应,制备内外贯通的多级孔聚苯乙烯微球,对微球的化学结构、形貌结构、粒径及分布、孔尺寸及分布等进行研究。结果显示,当单体苯乙烯浓度为15%,以乙醇为溶剂时,种子微球具有良好的单分散性,其平均粒径为3.75μm;SEM结果显示,微球表面粗糙,具有明显孔洞结构;比表面积分析也显示多级孔聚苯乙烯微球富含大孔、介孔和微孔,比表面积达到575.3 m 2/g,表明形成内外贯通的多级孔结构;随着对苯乙烯磺酸钠功能单体用量增加,微球表面Zeta电位明显增加。展开更多
A Web site always provides a large number of topics,so the browser is prone to lost the Way. In this paper we build a Navigation system for the Web site by using the model of Belief networks. It can help the browser t...A Web site always provides a large number of topics,so the browser is prone to lost the Way. In this paper we build a Navigation system for the Web site by using the model of Belief networks. It can help the browser to find the topics that he is interesting to quikly. It also can be used to optimize the structure of the Web site.展开更多
文摘在单分散聚苯乙烯种子微球合成基础上,通过两步溶胀法以及傅克(Friedel-Crafts)烷基化反应,制备内外贯通的多级孔聚苯乙烯微球,对微球的化学结构、形貌结构、粒径及分布、孔尺寸及分布等进行研究。结果显示,当单体苯乙烯浓度为15%,以乙醇为溶剂时,种子微球具有良好的单分散性,其平均粒径为3.75μm;SEM结果显示,微球表面粗糙,具有明显孔洞结构;比表面积分析也显示多级孔聚苯乙烯微球富含大孔、介孔和微孔,比表面积达到575.3 m 2/g,表明形成内外贯通的多级孔结构;随着对苯乙烯磺酸钠功能单体用量增加,微球表面Zeta电位明显增加。
文摘A Web site always provides a large number of topics,so the browser is prone to lost the Way. In this paper we build a Navigation system for the Web site by using the model of Belief networks. It can help the browser to find the topics that he is interesting to quikly. It also can be used to optimize the structure of the Web site.