基于硝酸铵气孔诱导剂的多孔TiO2薄膜的制备

采用在TiO2溶胶中加入硝酸铵的方法并通过浸渍-提拉技术制备了气孔修饰的TiO2薄膜。气孔的形成与溶胶液膜中硝酸铵诱导的分相现象相关，硝酸铵一方面抑制了干燥过程中凝结水分的挥发，另一方面增大了水相的表面张力，促使了水以球形水珠的形态分散在湿凝胶的表面，水珠挥发后形成气孔。所制备的气孔修饰的TiO2薄膜表现了超亲水性能。随着硝酸铵用量的增加，薄膜表面气孔的分布密度增大，可见光的透过率减小。增加涂膜次数可以获得多层次网络气孔结构的表面形态，多层次气孔结构的多次散射有利于提高可见光的透过性能。

Preparation of porous TiO2 thin film with a pore-directing agent of ammonium nitrate

Pore modified TiO2 thin films were prepared by adding ammonium nitrate into TiO2 sol precursor and using dip-coating technique.The formation process of pores in TiO2 thin film is closely related to the phase separation induced by ammonium nitrate in dip-coated TiO2 sol film.Ammonium nitrate in the dip-coated TiO2 sol film not only suppresses the evaporation of condensed water during the drying process but also increases the surface tension of water phase,which enhances the formation of water droplets which remains pores in the dried gel after being completely evaporated.The formed TiO2 thin films showed excellent superhydrophilicity.The pore distribution density increased and the transmittance of visible light deceased as the amount of ammonium nitrate was increased.Increase of repeating times of the coating process produced a multilayer pore modified film surface which was favorable to increase the transmittance of visible light.