Functionalization of cotton fabrics with highly durable polysiloxane–TiO2 hybrid layers: potential applications for photo-induced water–oil separation, UV shielding, and self-cleaning

Abstract

Using a facile strategy to prepare multifunctional cotton fabrics with switchable superhydrophobicity–superhydrophilicity, UV-resistance, photo-induced water–oil separation, and self-cleaning properties is an important and urgent issue in the sustainable development of natural fibers. Herein, a new type of surface modified cotton fabric with a polysiloxane–TiO₂ hybridized coating (Cot-g-PMAPS/TiO₂) was prepared through radiation-induced graft polymerization and sol–gel technology. The hybridized coating was composed of two sub-layers: an inner part consisting of an organic–inorganic hybrid layer to address the issue of self-degradation of TiO₂-loaded polymeric materials while simultaneously improving the adhesion of the TiO₂ film to its support, and an outer part consisting of nanocrystalline anatase TiO₂ to endow the cotton fabric with multifunctionality. The influence of the polysiloxane–TiO₂ on the structure and integrated performance of Cot-g-PMAPS/TiO₂ was systematically studied. The results showed that the polysiloxane–TiO₂ coating improved the UV absorption capacity 5.6-fold compared with that of the untreated cotton fabric. In addition, the retention of the break strength of Cot-g-PMAPS/TiO₂ was 95.6% after 192 h of UV irradiation. Since the polysiloxane–TiO₂ coating is chemically bound to the cotton fibers, the Cot-g-PMAPS/TiO₂ fabric possesses long-term stability, ultra-high durability, and robustness. After 20 commercial or domestic launderings, the UV absorption intensity and WCAs were almost the same as those of the newly fabricated material. The Cot-g-PMAPS/TiO₂ also exhibits photo-induced water–oil separation and self-cleaning based on the switchable superhydrophobicity–superhydrophilicity and the photoactivity of TiO₂. This study provides an interesting insight into the design of a novel functional material based on a controllable surface structure.