硅酸钠溶液综述：结构、凝胶化和脱水收缩,Advances in Colloid and Interface Science

硅酸钠溶液（也称为水玻璃）已被发现在各种应用中具有显着的效用。70 年各种分析的累积证据表明，硅酸盐溶液由多种物质组成，从单体到低聚物，再到胶体。此外，这些物质的结构和分布很大程度上取决于许多参数，例如溶质浓度、硅碱比、pH 值和温度。硅酸盐溶液最有趣和最典型的特性是它们形成硅胶的能力。总体而言，尽管使用不同的光谱和散射技术进行了广泛的研究，但与硅酸钠的动态结构、稳定性、聚合和凝胶化相关的许多问题仍然难以回答。为了响应溶液和环境参数的变化，在原子尺度上重组硅酸盐物质的大量同步反应使得仅使用实验数据来研究单个事件变得困难。分子建模提供了另一种研究水性硅酸盐和硅胶系统中未知区域的方法，从而对微观长度尺度的化学反应产生重要的见解。然而，足够的采样仍然是这些系统分子模拟实际应用的一个挑战。基于实验和建模研究，本文详细讨论了硅酸钠溶液的结构和形态、其胶凝机制和动力学以及脱水收缩现象。其目标不仅是回顾当前对硅酸钠溶液、硅胶和适合研究它们的表征技术的理解水平，而且是找出文献中的空白，并为推进有关这些复杂系统的知识开辟机会。我们认为，未来的研究方向应该是关联硅酸盐溶液中相互作用和反应的原子、分子和介观尺度细节，并建立对其凝胶机制和动力学的基本理解。我们相信，这些知识可以消除制造中的“试错”方法，并改善从这些解决方案衍生的重要材料（例如硅胶和沸石）合成中的结构控制。

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Sodium silicate solutions, also known as waterglass, have been found to have remarkable utility in a variety of applications. The cumulative weight of evidence from 70 years of varied analysis indicates that silicate solutions consist of a wide range of species, from monomers through oligomers, up to colloids. Moreover, the structure and distribution of these species are greatly dependent upon many parameters, such as solute concentrations, silica to alkali ratio, pH, and temperature. The most interesting and characteristic property of silicate solutions is their ability to form silica gels. Overall, despite extensive research using different spectroscopic and scattering techniques, many questions related to sodium silicate's dynamic structure, stability, polymerization, and gelation remain difficult to answer. The multitude of simultaneous reactions which restructure the silicate species at the atomic scale in response to variation in solution and environmental parameters, makes it difficult to investigate the individual events using only experimental data. Molecular modelling provides an alternative way to study the unknown areas in the aqueous silicate and silica gel systems, generating key insights into the chemical reactions at microscopic length scales. However, sufficient sampling remains a challenge for the practical use of molecular simulation for these systems. Based on both experimental and modelling studies, this review provides a detailed discussion over the structure and speciation of sodium silicate solutions, their gelation mechanism and kinetics, and the syneresis phenomenon. The goal is not only to review the current level of understanding of sodium silicate solutions, silica gels and characterization techniques suitable for studying them, but also to identify the gaps in the literature and open up opportunities for advancing knowledge about these complex systems. We believe that the future direction of research should be toward correlating atomistic, molecular, and meso-scale level details of interactions and reactions in silicate solution and establishing a fundamental understanding of its gelation mechanism and kinetics. We believe that this knowledge could eliminate the “trial and error” approach in manufacturing, and improve structural control in the synthesis of important materials derived from these solutions, such as silica gels and zeolites.