Hydrophobic surface modification of TiO ₂ nanoparticles for production of acrylonitrile-styrene-acrylate terpolymer/TiO ₂ composited cool materials

Hydrophobic surface modification of TiO ₂ was conducted for production of acrylonitrile-styrene-acrylate (ASA) terpolymer/titanium dioxide (TiO ₂ ) composited cool materials. Different amount of 3-methacryloxypropyl-trimethoxysilane (MPS) was employed to change hydrophilic surface of TiO ₂ into hydrophobic surface. The hydrophobic organosilane chains were successfully grafted onto TiO ₂ through Si[sbnd]O[sbnd]Ti bonds, which were verified by Fourier transformed infrared spectra and X-ray photoelectron spectroscopy. The water contact angle of the sample added with TiO ₂ modified by 5 wt% MPS increased from 86° to 113°. Besides, all the ASA/TiO ₂ composites showed significant improvement in both solar reflectance and cooling property. The reflectance of the composites throughout the near infrared (NIR) region and the whole solar wavelength is increased by 113.92% and 43.35% compared with pristine ASA resin. Simultaneously, significant drop in temperature demonstrates excellent cooling property. A maximum decrease approach to 27 °C was observed in indoor temperature test, while a decrease around 9 °C tested outdoors is achieved.