Urade Vikrant N, Hillhouse Hugh W
J Phys Chem B. 2005 Jun 2;109(21):10538-41. doi: 10.1021/jp051229+.
Thin films of nanoporous tin oxide with a 3D face-centered orthorhombic nanostructure have been synthesized by self-assembly that is controlled by post-coating thermal treatment under controlled humidity. In contrast to the conventional evaporation-induced self-assembly (EISA), the films here have no ordered nanostructure after dip-coating. However, the initial coatings are formed under conditions that inhibit significant hydrolysis and condensation for extended periods. This allows the use of postsynthesis thermal vapor treatments to completely control the formation of the nanostructure. With EO106-PO70-EO106 (Pluronic F127) triblock copolymer as the template, highly ordered nanostructures were generated by exposing the disordered films to a stream of water vapor at elevated temperature, which rehydrates the films and allows the formation of the thermodynamically favored phase. Further exposure to water vapor drives the condensation reaction through the elimination of HCl. The X-ray diffraction pattern from the nanostructure was indexed in the space group Fmmm as determined by analysis of 2D small-angle X-ray scattering patterns at various angles of incidence. The nanostructure is then stabilized and made nanoporous by extended controlled thermal treatments. After self-assembly and template removal, the films are thermally stable up to 600 degrees C and retain an ordered, face-centered orthorhombic nanostructure.
通过在可控湿度下进行后涂覆热处理控制的自组装方法，合成了具有三维面心正交纳米结构的纳米多孔氧化锡薄膜。与传统的蒸发诱导自组装（EISA）不同，这里的薄膜在浸涂后没有有序的纳米结构。然而，初始涂层是在长时间抑制显著水解和缩合的条件下形成的。这使得可以使用合成后热蒸汽处理来完全控制纳米结构的形成。以EO106-PO70-EO106（普朗尼克F127）三嵌段共聚物为模板，通过在高温下将无序薄膜暴露于水蒸气气流中，使薄膜再水化并形成热力学上有利的相，从而产生了高度有序的纳米结构。进一步暴露于水蒸气中通过消除HCl驱动缩合反应。通过分析不同入射角下的二维小角X射线散射图案确定，纳米结构的X射线衍射图案在空间群Fmmm中被索引。然后通过延长可控热处理使纳米结构稳定并形成纳米多孔。自组装和模板去除后，薄膜在高达600摄氏度的温度下热稳定，并保留有序的面心正交纳米结构。
