A photophysical study of the sol/gel transition in silica: Structural dynamics and oscillations, room-temperature phosphorescence and photochromic gel glasses
A photophysical study of the sol/gel transition in silica: Structural dynamics and oscillations, room-temperature phosphorescence and photochromic gel glasses
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DOI：
10.1016/0022-3093(86)90117-1
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发表时间：
1986-06
影响因子：
3.5
通讯作者：
V. Kaufman;D. Levy;D. Avnir
中科院分区：
文献类型：
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作者：
V. Kaufman;D. Levy;D. Avnir
我们报道了利用光物理探针研究四烷硅在水解和缩聚过程中的溶胶/凝胶转变，研究最终硅胶玻璃的性质，以及研究苯基和乙基三甲氧基硅烷水解过程中反相有机硅胶玻璃的形成。利用芘荧光和实验工艺，逐步探测溶胶从湿凝胶到干凝胶转变过程中结构变化的动态，并探测pH、水硅烷比和烷氧基等参数变化的影响。与二氧化硅表面的吸附不同，被困在二氧化硅玻璃中的芘只显示出单体发射。在加入表面活性剂后，观察到结构振荡。据我们所知，这是第一个远离平衡的耗散结构，其中聚合物系统振荡。我们还报道了最终凝胶玻璃作为有机分子的新型室温陷阱的使用。在无机玻璃中捕获有机分子的可能性开辟了许多新的机会和应用，其中两个被报道：(a)室温下获得了许多分子的磷光，例如芘。(b)描述了第一种有机染料（螺吡烷）/无机玻璃（SiO2）光致变色材料。
We report the use of photophysical probes for studying the sol/gel transition of silicon tetra-alkoxide undergoing hydrolysis and condensation-polymerization, for studying the properties of the final silica gel glass, and for studying the formation of reversed-phase organic silica gel glasses during hydrolysis of phenyl and ethyl trimethoxysilanes. Pyrene fluorescence and excimerization process were used to probe, stage by stage, the dynamics of the structural changes that occur during the sol to wet gel to dry gel transitions and to probe the effects of parameter changes such as pH, water/silane ratio and alkoxy groups. Unlike adsorption on silica surfaces, pyrene trapped in the silica glass shows monomeric emission only. Structural oscillations are observed upon addition of surface active agent. To the best of our knowledge, this is the first far-from-equilibrium dissipative structure, in which a polymeric system oscillates. We also report the uses of the final gel glass as a novel room-temperature trap of organic molecules. The possibility to trap an organic molecule in inorganic glass opens many new opportunities and applications, two of which are reported: (a) Room temperature phosphorescence is obtained for a number of molecules, e.g., pyrene. (b) The first organic-dye (spiropyrane)/inorganic glass (SiO2) photochromic material is described.