络合剂对制备TiO_2薄膜的影响以及超亲水特征

Superhydrophilic TiO_2 Film Prepared with the Assistance of Complexing Agents

采用溶胶-凝胶技术,以钛酸丁酯(Ti(OC4H9)4)为前驱体,加入乙酰丙酮(acac)和二乙醇胺(DEA)作为络合剂,在玻璃基片上制备了TiO2多孔薄膜。通过SEM观察了多孔薄膜的表面形貌,探讨了样品在溶胶-凝胶及烧结过程中孔状结构的形成过程,并测量了薄膜的表面润湿性。实验结果表明,单独以acac或DEA作为络合剂制备的涂膜十分致密和平坦,水接触角分别为20°和23°。但以二者复合使用,由于低缩聚物迅速形成使溶液体系产生二相分离,随着二乙醇胺加入量的增加,两相完全分离所需的时间逐渐减少,在煅烧过程中溶剂挥发时,气体放出就出现了孔状结构,从而使表面具有更大的平均粗糙度。多孔TiO2的涂膜在避光的条件下水接触角达6.5°。

A novel method was developed to produce a TiO2 film with circular pores on its surface.Macrospore structure can be obtained in the presence of two complexing agents of acetylacetone（acac） and diethanolamine（DEA） under a template-free condition.Notwithstanding,it has been found that irrespective of the kind of complexing agents,whether it is acac,or DEA,a common flat surface-formation process has been confirmed.In this account,acac or DEA added in the sols serve as stabilizers that impedes the hydrosis and polymerization among constituents during gel-forming reactions.But the situation has entirely changed when both acac and DEA were used as complexing agents.The hydrolysis is conducted under acidic conditions where a relatively narrow distribution of growing oligomers can be obtained.And the phase separation is driven by the reduction of miscibility between the polar solvent and polycondensed inorganic species.The phaseformation time would decline according the adding amount of DEA which triggers the process of hydrolysis under acidic conditions.The fluid phase of solvent mixture could oxidize and decompose to carbon dioxide which leaves numerous pores on the surface.The results show that the TiO2 film doped with two stabilizers exhibits superhydrophilic characteristic（6.5°） although it is not exposed to ultraviolet irradiation,comparing with flat ones（20° and 23°）.Finally,the formation mechanism and the property-structure relationship were discussed in details.