Fernandez-Martin Cristina, Edler Karen J, Roser Stephen J
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
Langmuir. 2004 Nov 23;20(24):10679-84. doi: 10.1021/la048424k.
Off-specular X-ray reflectivity measurements were carried out to follow the in situ development of surfactant-templated silica thin films at the air-water interface under conditions of controlled relative humidity and temperature, using an enclosed sample cell designed for this purpose. The results suggest a strong dependence of formation time and growth mechanism on ambient conditions. Thin films were synthesized at the air-water interface using cetyltrimethylammonium bromide (CTAB, 0.075 M) and a silica precursor, tetramethoxysilane (TMOS, 0.29-0.80 M) in an acidic medium. The studied humidity range was from 50 to 100%, the temperature was between 25 and 40 degrees C, and the TMOS/CTAB molar ratio was between 3.3 and 10.7. We observed that high humidity slows down the growth process due to lack of evaporation. However, increasing the temperature results in a decrease in the film-formation time. We proposed a formation mechanism for film growth as a consequence of phase separation, organic array assembly, and silica polymerization.
使用为此目的设计的封闭样品池，在控制相对湿度和温度的条件下，进行了非镜面X射线反射率测量，以跟踪空气-水界面处表面活性剂模板化二氧化硅薄膜的原位生长过程。结果表明，形成时间和生长机制强烈依赖于环境条件。在空气-水界面使用十六烷基三甲基溴化铵（CTAB，0.075 M）和二氧化硅前驱体四甲氧基硅烷（TMOS，0.29 - 0.80 M）在酸性介质中合成薄膜。研究的湿度范围为50%至100%，温度在25至40摄氏度之间，TMOS/CTAB摩尔比在3.3至10.7之间。我们观察到，由于缺乏蒸发，高湿度会减缓生长过程。然而，提高温度会导致成膜时间减少。我们提出了一种由于相分离、有机阵列组装和二氧化硅聚合而导致薄膜生长的形成机制。
