Phenyl grafted flexible-rigid hybrid organosilicon network with enhanced aging- and crack-resistance for sandstone cultural heritage conservation

Functionalization of conventional tetraalkoxysilane-derived organosilicon sols has been widely adopted to mitigate cracking issues in sandstone cultural heritage conservation. However, the introduction of inappropriate organic segments critically compromises aging resistance and practical utility. In this study, a phenyl-functionalized organosilicon sol (Ph-sol) is designed via copolymerization reaction between methylphenyldimethoxysilane and tetraethoxysilane, which synergistically enhances crack resistance and aging resistance. Spectroscopic characterizations confirm that the flexible Si–O–Si segments grafted with phenyl groups integrate into the rigid three-dimensional Si–O networks upon solidification. This molecular architecture endows the resulting xerogels with improved resistance to thermal aging (300 °C for 6 h), photoaging (550 W/m 2 for 168 h), and acid degradation (0.1 mol·L −1 H 2 SO 4 for 24 h). Furthermore, Ph-sol possesses good permeability (16.03 mm within 5 min) and can penetrate into the interior of weathered Yungang Grottoes sandstone to form a three-dimensional continuous consolidation network to achieve good consolidation performance. This synergy of crack resistance, triple anti-aging performance, and consolidation efficacy positions Ph-sol as a promising consolidant for acid-weathered sandstone in laboratory tests, warranting further evaluation under more realistic multi-factor weathering conditions.