Abstract

The research of the hydrolytic polycondensation kinetics of tetraethoxysilane (TEOS) is required in order to understand the sol-gel synthesis processes and identify the factors determining the direction of these processes. An extensive analysis of these problems permits us to predict appropriate ways for the synthesis of new substances with the predetermined properties. Studying the kinetics of the polycondensation of TEOS above the gel point will allow solving problems of the gels’ strength and the gels’ degree of structuring and thus optimizing the conditions of the further processing materials for the production of the final synthesis products. In this paper the results of the research on the structuring kinetics of the silica in the modeled aqueous-alcoholic solutions of TEOS, including boron-containing solutions, before and after the gel point at various molar ratios of H₂O : SiO₂ and pH values of 2.0 and 6.0 by the differential kinetic spectrophotometry are presented. The kinetic scheme developed by the authors and the mathematical tool allow determining the degree of the direction of the process of silica polycondensation. The data obtained on the model systems were applied to the description of the silica structuring process in the acid solutions resulting from the treatment of the single-phased sodium borosilicate glass. The obtained results will form the base for the interpretation of the experimental data on the kinetics of the silica structuring contained in the unstable phase of the two-phased alkali-borosilicate glass during the leaching process; i.e., it will allow predicting the dissolution rate, forms of existance, gelation time, strata formation time and, as a consequence, the formation of some porous structure of the resulting porous glass.

中文翻译：

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DK-分光光度法研究四乙氧基硅烷体系中的水解缩聚反应

摘要

为了了解溶胶-凝胶合成过程并确定决定这些过程方向的因素，需要对四乙氧基硅烷（TEOS）的水解缩聚动力学进行研究。对这些问题的广泛分析使我们能够预测合成具有预定性质的新物质的合适方法。研究在凝胶点以上的TEOS的缩聚动力学将解决凝胶的强度和凝胶的结构化程度的问题，从而优化用于最终合成产物生产的进一步加工材料的条件。本文研究了在TEOS建模的水-醇溶液（包括含硼溶液）中二氧化硅的结构动力学研究结果，₂ O：SiO ₂示差动分光光度法测定的pH值为2.0和6.0。作者和数学工具开发的动力学方案可以确定二氧化硅缩聚过程的方向。在模型系统上获得的数据可用于描述单相硼硅酸钠玻璃处理后的酸性溶液中的二氧化硅结构化过程。所得结果将为解释浸出过程中两相碱金属-硼硅酸盐玻璃不稳定相中所含二氧化硅结构动力学的实验数据奠定基础。也就是说，它可以预测溶解速率，存在形式，胶凝时间，地层形成时间，并因此，