Breathable hyperbranched polysiloxane for the conservation of silicate cultural heritages

The loose and porous structural nature of silicate cultural heritages makes them vulnerable to environmental changes. After thousands of years exposure, many of them are seriously degraded. Consolidation using certain conservation material is one of the most common methodologies to protect them. However, the vapor permeability of the relics often decreases significantly because conservation material fills the pores or changes the hydrophilicity of the relics, both blocking the vapor transportation. In this work, a novel hyperbranched polysiloxane is synthesized and its potential as conservation material for silicate cultural heritages is examined using sandstones from Yungang grottoes as mockup samples. The hyperbranched structure can lead to the formation of continuous, crack-free, and breathable network, which provides required reinforcement and remains most of the vapor permeability of the treated stone. Our results show that the as-prepared hyperbranched polysiloxane is highly potential for sandstone relics conservation, such as Yungang grottoes. Graphical abstract