All-weather self-healing superhydrophobic coating functionalized with the cauliflower-like PPy and TiN on cotton fabric for efficient oil-water separation

Superhydrophobic materials are currently undergoing rapid development in various industries, with increasing attention being paid to their service life. Herein, we report an all-weather self-healing superhydrophobic cotton fabric based on photothermal and Joule-heating effects, which can be used for efficient oil-water separation. With the assistance of Safranine T, unique cauliflower-like polypyrrole (PPy) was prepared. Subsequently, titanium nitride (TiN) was loaded to enhance the photothermal performance of the fabric, and polydimethylsiloxane (PDMS) was grafted onto surface to improve the water repellency of PPy@TiN/PDMS fabric. The fabric not only has strong light absorption in visible-near infrared region, but also has good Joule-heating effect, up to 116.3 °C (light intensity of 5 sun) and 128.5 °C (voltage of 8 V). Due to unique all-weather heating performance, the migration of low surface energy PDMS chains is accelerated, so that the PPy@TiN/PDMS fabric after air plasma etching and oxydation can quickly heal its water contact angle (WCA) to 156° under light or low voltage conditions. Additionally, the fabric demonstrates an outstanding performance for the separation of various oil-water mixtures and in multiple cycle separation experiments. This study presents a novel approach for extending the longevity of superhydrophobicity and addressing the issue of waste oil treatment.