TiO_2-SiO_2溶胶的制备和在水溶性聚氨酯中的分散行为

Preparation and characterization of TiO_2-SiO_2 sols dispersed in water soluble polyurethane

在SiO2质量分数不小于10％的酸性硅溶胶（粒径分别为13．7nm，26．8um）中，加入钛酸正丁酯异丙醇溶液，发生水解、聚合，生成水合TiQ2；紫外可见光谱和红外光谱及透射电镜观察证实了水合TiO2是进一步包覆在硅溶胶胶粒表面，形成了TiO2／SiO2质量比不小于10％的TiO2—SiO2溶胶。大粒径硅溶胶和钛酸正丁酯异丙醇溶液分2次或3次加入，有利于TiO2—SiO2溶胶的生成。包覆在硅溶胶胶粒表面的针状水合TiO2使TiO2—SiO2溶胶表现为膨胀型流动。在TiO2／SiO2为10％的TiO2—SiO2溶胶中加入质量分数为1％的水溶性聚氨酯（PU—E）水溶液，由于PU—E对TiO2—SiO2溶胶的保护作用，使该分散体系表现为牛顿型流动。

Tetrabutyl titanate diluted in isopropyl alcohol was hydrolyzed and polymerized to the hydrate titania sa soon as the diluted tetrabutyl titanate was added into the various acid silicas (dn were 13.7nm and 26.8nm ).The silica sphere coated with the hydrate titania was characterized by UV-vis and FT-IR. The mass ratio of TiO_2/SiO_2 was more than 10％. The three additions of diluted tetrabutyl titanate was good to formation of TiO_2-SiO_2 sol. The flow behavior of the TiO_2-SiO_2 sol was dilatant caused by the needle- shaped titania coated on the silica sphere. The water-soluble polyurethane protects the TiO_2-SiO_2 sol and made the dispersion of the TiO_2-SiO_2 sol behave the Newtonian folw.