Self-cleaning PDMS films with durable superhydrophobicity and photocatalytic capability based on TiO2-modified nanopillar array

Abstract

Self-cleaning films with superhydrophobicity and photocatalytic capability have attracted considerable interest in recent years for the synthetical chemical and physical self-cleaning performance to overcome individual inherent limitations. In the present work, a dual-functional self-cleaning film is proposed through the design of polydimethylsiloxane (PDMS) nanopillar array, swelling absorption of anatase-typed TiO2 nanoparticles, and final low-surface-energy modification of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (PFDTS). Benefiting from the hierarchically mountain-like structure constructed by the PDMS nanopillar array and swelling absorbed TiO2 nanoparticles, the self-cleaning film presents a robust superhydrophobicity to resist chemical and mechanical damages (e.g. solvent/acid/alkali immersion, stretching, water impact, and sand abrasion). Combining the photocatalytic activity with adequate loading of TiO2 nanoparticles, the self-cleaning film demonstrates a great degradation capability of organic pollutants with a degradation efficiency over 98 %. Importantly, owing to the superhydrophobicity repairability induced by the migration of fluorocarbon chains, the self-cleaning film can highly recover the water repellency with a water contact angle (WCA) of 155o even after long-term irradiation under UV light. The findings conceivably promote the development and application of the self-cleaning materials with superhydrophobic and photocatalytic properties.