Molecular structure determination of acid-initiated sodium silicate sol-gels via Raman spectroscopy

IF 3.5 3区材料科学 Q1 MATERIALS SCIENCE, CERAMICS

Journal of Non-crystalline Solids Pub Date : 2025-06-14 DOI:10.1016/j.jnoncrysol.2025.123671

Marzieh Matinfar, John A. Nychka

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Abstract

Silica gels derived from sodium silicate solutions (waterglass) show potential for bone scaffolds, but their structure under different processing conditions remains unclear. This study investigates the waterglass sol-gel transition using Raman spectroscopy. Silica gels were formed by mixing waterglass with boric and phosphoric acids, and Raman spectroscopy revealed structural changes during gelation. Basic gels predominantly contained higher-order silicate rings with Q³ (∼53–80 %), Q² (∼10–17 %), and Q⁰ (∼5–34 %) units, while acidic gels had lower-order rings with Q² (∼62–80 %) and Q⁰ (∼20–38 %) units. Raman analysis showed no significant changes at the gelation point, indicating gelation occurs via particle agglomeration by secondary bonds, rather than Si-O-Si bonds. Networks of agglomerated particles with structural units of varying degrees of polymerization resulted in distinct microstructures: basic gels formed less compact networks with larger pores, while acidic gels formed compact networks with smaller pores. These findings provide insights into chemically controlled silica gels with predictable structures.

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酸引发硅酸钠溶胶-凝胶分子结构的拉曼光谱测定

从硅酸钠溶液（水玻璃）中提取的硅胶显示出骨支架的潜力，但其在不同加工条件下的结构尚不清楚。本研究利用拉曼光谱研究了水玻璃溶胶-凝胶的转变。将水玻璃与硼酸和磷酸混合形成硅胶，拉曼光谱显示了凝胶过程中的结构变化。碱性凝胶主要含有高阶硅酸环，具有Q3（~ 53 - 80%）、Q2（~ 10 - 17%）和Q0（~ 5 - 34%）单元，而酸性凝胶含有低阶硅酸环，具有Q2（~ 62 - 80%）和Q0（~ 20 - 38%）单元。拉曼分析显示，凝胶点没有明显变化，表明凝胶是通过二级键而不是Si-O-Si键的颗粒聚集发生的。具有不同聚合程度结构单元的团聚颗粒网络形成了不同的微观结构：碱性凝胶形成的网络不致密，孔隙较大，酸性凝胶形成的网络致密，孔隙较小。这些发现提供了对具有可预测结构的化学控制硅胶的见解。

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来源期刊

Journal of Non-crystalline Solids 工程技术-材料科学：硅酸盐

CiteScore

6.50

自引率

11.40%

发文量

576

审稿时长

35 days

期刊介绍： The Journal of Non-Crystalline Solids publishes review articles, research papers, and Letters to the Editor on amorphous and glassy materials, including inorganic, organic, polymeric, hybrid and metallic systems. Papers on partially glassy materials, such as glass-ceramics and glass-matrix composites, and papers involving the liquid state are also included in so far as the properties of the liquid are relevant for the formation of the solid. In all cases the papers must demonstrate both novelty and importance to the field, by way of significant advances in understanding or application of non-crystalline solids; in the case of Letters, a compelling case must also be made for expedited handling.