Facile preparation of solar reflective cool colored material with desired superhydrophobicity

The application of cool materials efficiently relieves heat island effect and slows global warming through saving energy, meanwhile the non-white appearance would highlight their applications for avoidable architectural problems and dazzling risk. Since the applied silica (SiO2) was covered with hexamethyldisilazane, it was used for the desired superhydrophobicity. Herein, SiO2 was incorporated with colored pigments, including whitish titanium dioxide (TiO2), greenish chromium trioxide (Cr2O3) and reddish ferric oxide (Fe2O3), to prepare cool colored materials through casting method with the assistance of poly(styrene-acrylonitrile) (SAN) as the matrix. For comparison, Cr2O3 presented high solar reflectance and cooling property as rutile TiO2, which was better than that of Fe2O3. With the simultaneous incorporation of SiO2 and Cr2O3, the sample possessed the near-infrared (NIR) reflectance of 73.7%, SRI values higher than 70, and water contact angle of 163°. Thus, cool colored material with superhydrophobicity was successfully fabricated, where the green appearance would highlight its outdoor applicability.