Preparation and Performance of Thermal Insulation Waterborne Polyurethane Coatings Containing 3-Aminopropyltriethoxysilane Modified Organo-Bridged Silica Aerogel

As an emerging thermal insulation material, silica aerogel holds broad application prospects in building energy conservation. Silica aerogel based waterborne coatings are low thermal conductivity, readily applicable and environmentally friendly, offering significant advantages for improving building energy efficiency. However, the inadequate dispersibility and agglomeration tendency of silica aerogel in aqueous polymer systems adversely affect coating properties. To address this challenge, a waterborne polyurethane (WPU) coating incorporating 3-aminopropyltriethoxysilane-modified organo-bridged silica aerogel (APTES-OBSA) was developed. Integration of organic segments within organo-bridged silica aerogel (OBSA) framework enhanced compatibility of silica aerogel with organic polyurethane chains, thereby reducing aerogel agglomeration. 3-aminopropyltriethoxysilane (APTES) surface modification of OBSA introduced amino groups that strengthened interfacial interaction between OBSA-WPU, effectively enhancing aerogel dispersion within the aqueous polyurethane matrix. APTES-OBSA loading achieved 20 wt% in WPU composite coatings. Compared to neat WPU coating, the composite coatings achieved 21.6% reduction in thermal conductivity, 10 °C lower temperature under thermal irradiation, and 26.6% higher adhesion. Additionally, the composite coatings demonstrated enhanced thermal stability and good water resistance. The excellent comprehensive performance positions this material as a promising eco-friendly thermal insulation coating for building energy-saving applications.