Electric heated cotton fabrics with durable conductivity and self-cleaning properties

This study was carried out to improve durability and reduce conductivity degradation of polypyrrole-deposited cotton fabrics by introducting a superhydrophobic surface. An in situ polymerization method was used to polymerize the polypyrrole on the cotton fabric, and the surface energy was lowered using n-dodecyltrimethoxysilane to create a superhydrophobic surface. In particular, to investigate the durability of the conductivity according to the superhydrophobic surface, the changes of surface resistance were examined after repeated exposure to air, moisture, and friction. The polypyrrole-deposited cotton fabric displayed excellent electrical heating features originating from the conductive polymer, although the surface resistance was somewhat increased by the superhydrophobic coating. In addition, nano-roughness was obtained by the pyrrol-deposition on the fabric surface, creating a dual-roughness property required for the superhydrophobic surface. Accordingly, the conductive superhydrophobic cotton fabric had a contact angle of more than 150° and a shedding angle of less than 10°, maintaining superhydrophobicity even during electrical heating. Above all, the superhydrophobic layer contributed to the functional durability of the conductive fabrics by protecting the conductive layer. After atmospheric aging for 20 weeks, undergoing a water spray test for 20 cycles, and a rubbing test with tape, the increment of surface resistance of the superhydrophobic coated cotton fabrics with polypyrrole was increased by up to 30% compared to the polypyrrole treated specimen without the coating, which showed a decrease of conductivity of over 74%. It is confirmed that the self-cleaning properties can easily remove dirt on the cotton fabric surface by roll-off of water droplets, thereby preventing the degradation of conductivity due to moisture and contamination.