Highly effective hydrophobic solar reflective coating for building materials: Increasing total solar reflectance via functionalized anatase immobilization in an organosiloxane matrix

Abstract This paper reports the synthesis and investigation of the effectiveness of a solar reflective coating designed for building materials having properties, such as substrate penetration, water repellency, slip resistance, durability, and reduction of heat in the buildings. The coating was synthesized via stabilization and incorporation of anatase TiO2 particles in an organosiloxane matrix using a sol–gel technique. Organosiloxane matrices are transparent and easy to process, which makes them an ideal host material to immobilize and incorporate TiO2 particles as scattering centers, which have a high index of refraction (2.5–2.7). For this reason, functional inorganic–organic hybrid composite materials are excellent candidates for novel solar reflective coatings. In application, the coating also acts as a multifunctional protective layer for building materials. In this work, we characterize various functionalities of the organosiloxane coating, including surface hydrophobicity, static friction, and durability. We observed the temperature reduction of 4.1 °C (8 °F) inside the cement mortar composite (CMC) treated with such coating, exhibiting excellent hydrophobicity, slip resistance, and longevity. The significant reduction in temperature is attributed to efficient light scattering by embedded TiO2 particles.