十二烷基苯磺酸钠改性的尿素和甲醛聚合杂化法合成氧化硅微球

本文在存在十二烷基苯磺酸钠时利用正硅酸乙酯水解液中尿素和甲醛的结晶性聚合反应合成得到了氧化硅微球。首次考察了尿素和甲醛的物质的量比、尿素和甲醛的总用量、正硅酸乙酯(TEOS)用量、酸用量、以及十二烷基苯磺酸钠用量对所得氧化硅微球结构和形貌特征的影响。适当选择这些用量范围可以得到结构稳定、分散均匀的氧化硅微球。在微球生长中尿素和甲醛的量不足时,其突出的结晶性聚合与氧化硅杂化反应进程相互影响,导致了氧化硅微球核壳结构的形成。酸用量增加使氧化硅微球的孔径分布从复杂的双峰转变成均匀的单峰。表面活性剂的使用使氧化硅微球的孔分布从0～80 nm范围内的连续分布转化成单一分布。这些结果对正硅酸乙酯水解液直接合成氧化硅微球方法的推广和应用具有重要指导意义。

Syntheses of Silica Microspheres by SDBS-Modified Urea-Formaldehyde Polymer Hybridization

Silica microspheres have been synthesized by crystalline polymerization reaction of urea and formaldehyde in tetraethoxysilane hydrolyzate in the presence of sodium dodecyl benzene sulfonate. Influence of the molar ratio of urea to formaldehyde, amounts of urea and formaldehyde, tetraethoxysilane(TEOS), acid, as well as sodium dodecyl benzene sulfonate on the structure and feature of silica microspheres is first investigated in this study. The suitable parameters above can lead to the silica microspheres with structural stability and uniform dispersion. The nuclear shell structure of silica microspheres could form in the reaction condition of insufficient amount of urea and formaldehyde, under the circumstances of outstanding crystalline polymerization of urea and formaldehyde following by prominent silica hybridization. With the increase of acidity in the reaction system, the twin peaks of silica microsphere pore size distribution turn into a uniform single peak. The use of surfactant made the pore size distribution of the silica microspheres from a continuous range of 0 to 80 nm into a single peak. These results are of importance for the extending and application of directly synthesizing silica microspheres in tetraethoxysilane hydrolyzate.