聚苯乙烯多孔薄膜的密度梯度控制

Control of density gradient in polystyrene porous films

利用单分散的SiO2微球自组装制备了含一种尺寸微球的SiO2胶体晶体和含多种尺寸微球的多层异质结构。对含一种尺寸微球的SiO2胶体晶体进行煅烧和刻蚀处理后,胶体晶体中空隙所占比例大于立方密堆结构的26%,形成了非密堆结构,而且刻蚀时间越长,空隙比例越大。在同样的热处理和刻蚀条件下,微球尺寸越小的胶体晶体被刻蚀的程度越高,结构中空气空隙所占的比例越大。对SiO2多层异质结构经过煅烧和刻蚀处理后,得到了空隙梯度变化的多层结构,以此为模板制备了密度梯度变化的聚苯乙烯多孔薄膜。薄膜各层之间形成了平滑的过渡,没有显示出明显的层间缺陷,且孔与孔之间没有出现3维有序多孔结构中常见的大的连通孔道。

Silica colloidal crystals and multilayer heterostructures were fabricated by using monodisperse silica microspheres. Non-closely-packed colloidal crystals, whose volume ratio of voids was larger than 26% in face-centered closely-packed structure, were obtained after calcining and etching silica colloidal crystals sequentially. The volume ratio of voids increases as the etching time is prolonged. It was found that the smaller the spheres forming colloidal crystals were, the bigger the ratio of voids was, after colloidal crystals were etched under the same condition. Graded silica colloidal films were obtained by calcining and etching silica multilayer heterostructures, which were used as templates to prepare polystyrene porous films with graded density. The different layers in porous films displayed a smooth transition where there were no obvious interlayer defects. Moreover, there were no large channels between pores that existed in conventional three-dimensionally ordered porous structures.