Ghosh Kaustav, Lehmler Hans-Joachim, Rankin Stephen E, Knutson Barbara L
Department of Chemical and Materials Engineering, University of Kentucky, 177 Anderson Hall, Lexington, Kentucky 40506-0046, USA.
Langmuir. 2005 Jul 5;21(14):6145-9. doi: 10.1021/la050311t.
The effect of processing mesoporous silica thin films with supercritical CO2 immediately after casting is investigated, with a goal of using the penetration of CO2 molecules in the tails of fluorinated surfactant templates to tailor the final pore size. Well-ordered films with two-dimensional hexagonal close-packed pore structure are synthesized using a cationic fluorinated surfactant, 1-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)pyridinium chloride, as a templating agent. Hexagonal mesopore structures are obtained for both unprocessed films and after processing the cast films in CO2 at constant pressure (69-172 bar) and temperature (25-45 degrees C) for 72 h, followed by traditional heat treatment steps. X-ray diffraction and transmission electron microscopy analysis reveal significant increases in pore size for all CO2-treated thin films (final pore diameter up to 4.22 +/- 0.14 nm) relative to the unprocessed sample (final pore diameter of 2.21 +/- 0.20 nm) before surfactant extraction. Similar pore sizes are obtained with liquid and supercritical fluid treatments over the range of conditions tested. These results demonstrate that combining the tunable solvent strength of compressed and supercritical CO2 with the "CO2-philic" nature of fluorinated tails allows one to use CO2 processing to control the pore size in ordered mesoporous silica films.
研究了浇铸后立即用超临界二氧化碳处理介孔二氧化硅薄膜的效果，目的是利用二氧化碳分子在氟化表面活性剂模板尾部的渗透来调整最终孔径。使用阳离子氟化表面活性剂1-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-十七氟癸基)吡啶鎓氯化物作为模板剂，合成了具有二维六方密堆积孔结构的有序薄膜。对于未处理的薄膜以及在恒定压力（69-172巴）和温度（25-45摄氏度）下将浇铸薄膜在二氧化碳中处理72小时，然后进行传统热处理步骤后，均获得了六方介孔结构。X射线衍射和透射电子显微镜分析表明，相对于表面活性剂萃取前的未处理样品（最终孔径为2.21±0.20纳米），所有经二氧化碳处理的薄膜的孔径都有显著增加（最终孔径高达4.22±0.14纳米）。在测试的条件范围内，液体和超临界流体处理获得了相似的孔径。这些结果表明，将压缩和超临界二氧化碳的可调溶剂强度与氟化尾部的“亲二氧化碳”性质相结合，可以使用二氧化碳处理来控制有序介孔二氧化硅薄膜的孔径。
