A fully waterborne coating system based on thiol-ene click reaction for robust and self-healing superhydrophobic surfaces

Waterborne superhydrophobic coatings are highly desirable for low cost, volatile organic compounds (VOCs)-free, and environmentally friendly processing, but such coatings are not easy to prepare due to the difficulty in dispersing low-surface-energy substances in water. In this work, we design a new approach to a fully waterborne coating system for preparing mechanically robust superhydrophobic surfaces, based on UV induced thiol-ene click reaction between pentaerythritol oleate (PETO) and 3-mercaptopropyltriethoxysilane (MPTES). A coating precursor (PM) is first prepared by UV-irradiating the mixture of PETO and MPTES (solvent-free) in the presence of photoinitiator 1173. The waterborne PM dispersion (WPM) is then obtained by emulsifying PM in water. After coated with PTFE nanoparticle-containing WPM, various substrates including cotton fabric, wool fabric, polyester fabric, carpet, sponge and wood plate exhibit water contact angle greater than 160°. The coating is durable enough against repeated accelerated washing (20 cycles) and Martindale abrasion (2000 cycles). Besides increasing the surface roughness, nanoparticles such as TiO2 NPs and CNTs can provide additional functions such as UV blocking, photocatalytic, and galvanostatic charge–discharge properties. The photo-thermal effect of CNTs under near-infrared light (0.18 W cm−2, 10 min) is also useful for healing the superhydrophobic fabrics after repeated washing or abrasion. Such a novel way for preparing fully waterborne dispersions has the potential for promoting the development of safe, environmentally friendly, and mechanically robust superhydrophobic coatings.