文章摘要
全硅氧键硅单体对苯丙乳液聚合稳定性及性能的影响
Effect of Siloxane Monomeron Stability of Emulsion Polymerization and Coating Performance
  
DOI:10.16865/j.cnki.1000-7555.2018.07.001
中文关键词: 全硅氧键硅单体  苯丙乳液  乳液聚合稳定性  正硅酸四甲酯  纳米二氧化硅
英文关键词: siloxane monomer  styrene-acrylic latex  stability of emulsion polymerization  tetramethoxysilane  nano-silica
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作者单位
夏宇正,崔永恒,陈晓农,石淑先 北京化工大学 碳纤维及功能高分子教育部重点实验室,北京 100029 
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中文摘要:
      利用全硅氧键硅单体与丙烯酸酯、苯乙烯进行乳液共聚,一直是直接制取纳米二氧化硅苯丙复合乳液的理想方法,但因硅氧键水解速度快于丙烯酸酯与苯乙烯的自由基聚合速度,故存在聚合稳定性差的问题。文中先以正硅酸四甲酯、环己醇和甲基丙烯酸羟乙酯为原料,正己烷为甲醇共沸剂,通过两步酯交换反应,制得了不同疏水性的全硅氧键乙烯基不饱和硅单体;然后以其为功能单体,经乳液聚合制得可在成膜过程中就地生成纳米二氧化硅的复合苯丙乳液。通过气相色谱-质谱联用技术,分析了酯交换产物中的主要组分;用透射电子显微镜、X射线衍射、Zeta电位及激光粒度测试、铅笔划痕硬度对乳液及乳胶膜进行了表征。结果表明,硅单体加入量在30%(质量分数)时,乳液聚合仍有很好的稳定性;乳胶粒粒径分布较窄,粒径约100nm;乳胶膜中存在纳米二氧化硅晶体,膜硬度达H 级。
英文摘要:
      It would be a much perfect method to prepare nano-silica/styrene-acrylic composite latex through emulsion polymerization of siloxane monomer with acrylate and styrene. However, the emulsion polymerization stability is very poor since the hydrolysis rate of siloxane is always faster than the radical polymerization rate of acrylates and styrene. In this paper,the whole siloxane unsaturated monomers with different hydrophobicity were synthesized through trans-esterification of tetra-methoxysilane with cyclohexanol and/or hydroxyethyl methacrylate in the presence of n-hexane which was used as methanol azeotrope. Then, the nano-silica/styrene-acrylic composite latice which can generate greatly nano-scale SiO2 during film forming were prepared through emulsion polymerization of the above whole siloxane unsaturated monomers with acrylates and styrene. First of all, the composition of the above siloxane monomer was determined by gas chromatography-mass spectrometer. Thus, the particle size and distribution of above latex and the morphology of colloidal particle were characterized by laser granularity analyzer and transmission electron microscopy respectively, and the crystalline silica in the film was identified by X-ray diffraction. The hardness of coating film was tested by pencil scratching tester. All the results show that the title nano-silica/styrene-acrylic composite latice exhibit excellent polymerization stability even if the amount of siloxane monomer reaches 30% to total monomer and their particle distribution is narrow to 100 nm. Another hand, the crystalline silica can be found evidently in the coating film, and the film hardness can reach H degree.
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