Hydrophobic surface modification of TiO₂ nanoparticles for production of acrylonitrile-styrene-acrylate terpolymer/TiO₂ composited cool materials

Highlights: • A hydrophobic surface is achieved with the assistance of silane coupling agent. • The composited cool materials show high NIR and solar reflectance. • The composited cool materials perform excellent cooling property. • Excellent mechanical properties are achieved due to the surface modification. • Building the reaction model between silane coupling agent and TiO₂. - Abstract: Hydrophobic surface modification of TiO₂ was conducted for production of acrylonitrile-styrene-acrylate (ASA) terpolymer/titanium dioxide (TiO₂) composited cool materials. Different amount of 3-methacryloxypropyl-trimethoxysilane (MPS) was employed to change hydrophilic surface of TiO₂ into hydrophobic surface. The hydrophobic organosilane chains were successfully grafted onto TiO₂ through Si−O−Ti bonds, which were verified by Fourier transformed infrared spectra and X-ray photoelectron spectroscopy. The water contact angle of the sample added with TiO₂ modified by 5 wt% MPS increased from 86° to 113°. Besides, all the ASA/TiO₂ 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.