Mercapto-functionalized siloxane for enhanced conservation of tremolite jade artifacts

Abstract

Numerous tremolite jade artifacts from archaeological sites exhibit powdering damage, necessitating immediate consolidation. However, research on jade consolidants remains limited. Siloxane is a promising material, yet its effectiveness is hindered by high levels of non-silicate components, such as calcium and magnesium, in tremolite. In this study, mercapto-functionalized siloxane sols with varying mercapto group contents were synthesized via sol–gel chemistry using (3-mercaptopropyl) trimethoxysilane (MPTS), (3-aminopropyl) dimethoxymethylsilane (APDMOS), and tetraethoxysilane (TEOS). Their consolidation effects on tremolite jade were evaluated. Results showed that mercapto-functionalized siloxane exhibited stronger performance than non-functionalized siloxane. This improvement stems from its dual functionality: alkoxy groups undergo hydrolysis and polycondensation to form highly polymerized xerogels that fill microvoids, while thiol groups (–SH) coordinate with calcium and magnesium ions in tremolite, acting as a functional “glue” to bind particles. Mercapto-functionalization thus offers a promising strategy to optimize jade consolidation and improve compatibility with non-silicate substrates.