Order and orientation control of mesoporous silica films on conducting gold substrates formed by dip-coating and self-assembly: a grazing angle of incidence small-angle X-ray scattering and field emission scanning electron microscopy study.
Order and orientation control of mesoporous silica films on conducting gold substrates formed by dip-coating and self-assembly: a grazing angle of incidence small-angle X-ray scattering and field emission scanning electron microscopy study.
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通过浸涂和自组装形成的导电金基底上介孔二氧化硅薄膜的有序和取向控制：入射掠角、小角 X 射线散射和场发射扫描电子显微镜研究。
DOI：
10.1021/la050595h
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
H. Hillhouse
中科院分区：
文献类型：
--
作者：
M. Tate;Brian W. Eggiman;J. Kowalski;H. Hillhouse
掠射角小角 X 射线散射 (GISAXS) 和高分辨率场发射扫描电子显微镜已用于表征导电金基底上 PEO20-PPO70-PEO20 (Pluronic P123) 模板介孔二氧化硅薄膜的中间相对称性、取向和长程有序性，作为二氧化硅与环氧乙烷 (Si/EO) 块比和相对湿度 (RH) 的函数。这些薄膜是通过浸涂形成的，然后在严格控制的相对湿度下蒸发诱导自组装。中间相的总体演变遵循基于 PEO 块膨胀导致的形状因素所预期的趋势。然而，发现纳米结构相对于基底的方向变化和长程有序程度取决于 Si/EO 比率。这些效应可能是由于蒸发和自组装的动力学造成的。一般来说，当 Si/EO 比率低于 3.29 时，薄膜中包含纳米结构相对于基材平面未定向的区域。然而，当 Si/EO 比率大于 3.62 时，发现薄膜的纳米结构相对于基材平面高度取向。在研究的 RH 范围内都是如此，与纳米结构的对称性无关。对于最高 RH 水平下的低 Si/EO 比，薄膜由球形和圆柱形孔的混合物组成。在高 Si/EO 比率和高 RH 水平下，薄膜具有高度定向的 R-3m 纳米结构，但在 GISAXS 图案上的布拉格点中显示出垂直于基底的条纹。这种条纹被解释为沿着平行于基底的平面的断层。
Grazing-angle of incidence small-angle X-ray scattering (GISAXS) and high-resolution field emission scanning electron microscopy have been used to characterize the mesophase symmetry, orientation, and long-range order in PEO20-PPO70-PEO20 (Pluronic P123) templated mesoporous silica thin films on conducting gold substrates as a function of silica-to-ethylene oxide (Si/EO) block ratio and relative humidity (RH). The films are formed by dip-coating followed by evaporation-induced self-assembly under tightly controlled RH. The general evolution of the mesophase follows the trends that are expected based on shape factors due to swelling of the PEO block. However, changes in orientation of the nanostructure relative to the substrate and the degree of long-range order are found to depend on Si/EO ratio. These effects are likely due to the dynamics of evaporation and self-assembly. Generally, at Si/EO ratios lower than 3.29, the films contained regions where the nanostructure was not oriented relative to the plane of the substrate. However, for Si/EO ratios greater than 3.62, conditions were found where the nanostructure of the film was highly oriented relative to the plane of the substrate. This is true over the range of RH studied, independent of the nanostructure symmetry. For low Si/EO ratios at the highest RH levels, the films were composed of a mixture of spherical and cylindrical pores. At high Si/EO ratios and high RH levels, the films had a highly oriented R-3m nanostructure but displayed streaking perpendicular to the substrate in the Bragg spots on GISAXS patterns. This streaking is interpreted as faulting along planes parallel to the substrate.