Facile synthesis of self-cured borosilicone resin catalyzed/modified with boric acid for transparent, self-adhesive and high-temperature resistant coating

Silicone resin, an organic-inorganic hybrid structure with an alternating Si-O-Si main chain, exhibits outstanding thermal stability, weather resistance, and electrical insulation, making it widely used in thermal protection materials, electronic packaging, and polymer-derived ceramics. However, its poor bonding performance and long curing temperature limit its potential application. Although introducing heteroatoms to form Si-O-X bonds enhances its thermal stability hardness and adhesion, existing modification methods suffer from long reaction times and require large amounts of organic solvents or halogen catalysts. In this work, we report a green and facile synthesis of borosilicone resin (BSi n R) via boric acid (BA) catalyst/modification without using halogen catalysts or organic solvents. Notably, introduction of boron element (B) significantly enhances the activity of the connected silicon methoxy groups, enabling room-temperature self-curing in humid environments by reducing curing temperature and time. When applied as a corrosion-resistant coating, BSi n R shows over 90 % visible light transmittance and 4H pencil hardness, and effectively protects tinplate from corrosion in 3.5 wt% NaCl solution. Additionally, at high temperatures, B promotes more complete and stable residual carbon structures on cured samples, effectively increasing T 5% to 402.5 °C and char yield to 84.9 %. Owing to its low viscosity, long-term storage stability (>2 months without precipitation), and excellent comprehensive properties, this facilely prepared BSi n R holds broad application prospects in aerospace, electronic packaging, and extreme-environment anti-corrosion coatings.