Preparation of wetting switchable cotton fabrics by free radical polymerization and its on-demand oil-water separation research

The rapid development of the global economy has led to frequent oil spills, resulting in environmental problems that seriously threaten human beings and marine water ecosystems. Therefore, the development of a superwetting material with a specific selective permeability using a natural polymer cotton fabric as a substrate is advantageous in separating different types of oil/water mixtures in complex environments. In this study, a cotton fabric with pH-responsive superwetting was investigated for selective on-demand separation of different types of oil phases. Firstly, vinyltrimethoxysilane (VTMS) was reacted by hydrolysis condensation, and SiO2 nanoparticles were anchored to the surface of cotton fabrics, which increased the roughness of cotton fabrics, and in turn provided reactive vinyl groups. Subsequently, tetradecyl methacrylate (TDMA), 10-undecenoic acid (UA), and VTMS were reacted by free radical polymerization to form a random copolymer. Thus, superhydrophobic long carbon alkyl chains and pH-responsive carboxyl group act synergistically to construct pH-responsive superwetting cotton fabrics. As-prepared cotton fabrics exhibited fast and stable reversible conversion of wettability in acidic/neutral and alkaline environments. For different types of oil/water mixtures, the separation efficiency reached more than 99% for high density oil/water mixtures and more than 95% for light density oil/water mixtures, as well as excellent recyclability and stability. Compared to the previously reported literature, for the separation of oil/water mixtures, the pH-responsive superwetting cotton fabrics prepared in this study suggested excellent separation efficiency. Therefore, it can be applied to the effective separation of different types of oil/water mixtures in real life and industrial production.