砂岩类文物是世界历史文化遗产的重要组成部分，包括古建筑、石窟寺、石刻雕像和历史纪念碑等。由于砂岩本身的特性以及户外因素的影响，这类文物受温度、湿度、水、可溶盐、紫外线等的侵蚀，出现不同程度的劣化。为了保护这些文物，亟需开发合适的材料对其进行有效保护，保护或延缓这些因素造成的侵蚀和破坏。

  近期，西安交通大学和玲/潘爱钊课题组针对硅酸盐材质的砂岩基石窟文物风化病害的特征及病害形成机理（砂岩内部胶结质流失）等问题，将膨润土基抗膨胀水凝胶在砂岩基文物中原位形成以弥补流失的胶结质。首先通过组分和条件控制调控了膨润土基水凝胶的原位形成时间和抗膨胀性，进而通过荧光示踪技术研究了膨润土基水凝胶材料在砂岩内部的分布，并深入评估了其在砂岩中的长效保护效果，最终研究了其户外应用。该成果在期刊《ACS Applied Materials & Interfaces》上发表，题为“Insight into a Bentonite-based Hydrogel for the Conservation of Sandstone-based Cultural Heritage: In-situ Formation, Reinforcement Mechanism, and High-Durability Evaluation”的文章（DOI: https://doi.org/10.1021/acsami.2c13122）。

Figure 1. (a) Chemical structure scheme of B-H hydrogel. (b) Schematic illustration of the bentonite-based hydrogel (B-H) formed in-situ in sandstone.

Figure 2. Sandstones (a) after protecting with B-H and (b) traditional hydrogel.

Figure 3. (a) Chemical structure and optical images of the Carbon quantum dots (CQDs) used for fluorescent tracer. Photographs of the appearance (b), cross-sectional surface (b₁ and b₃) of the sandstones treated by hydrogel-CQDs. Photograph of the appearance (b₂) of the fresh sandstones. (c) Morphology and element distribution of Si, C and N elements in the internal grains of the treated sandstone by SEM-mapping. (d) Morphology of the internal grains of the treated sandstone by SEM. (e) Schematic diagram of in-situ formation of hydrogel inside the sandstone.

Figure 4. (a) Acid resistance, (b) salt crystallization cycles in moisture and heat, and (c) freeze-thaw cycles of unprotected and B-H-sandstone. (d) Schematization of the protecting mechanism for freeze-thaw resistance and salt resistance for B-H- sandstone.

Figure 5. Application of bentonite-based hydrogel on actual sandstone-based cultural heritage at Dafo Si. Sampling areas are indicated with red rectangles. Photographs of the sandstones before (a) and after (b) protecting by bentonite-based hydrogel.

  全文链接：https://pubs.acs.org/doi/full/10.1021/acsami.2c13122