Polypyrrole-Coated Woven Fabric as a Flexible Surface-Heating Element

Polypyrrole (PPy) was coated sequentially by chemical and electrochemical methods on a woven fabric, giving rise to a fabric having high electrical conductivity. We investigated the effects of the preparation conditions on the various properties of the resulting fabric. The PPy-coated fabric with optimum properties was obtained when it was prepared sequentially by chemical polymerization at the elevated temperature of 100$^{\circ}C$ under a pressure of 0.9 kgf/$\textrm{cm}^2$ and then electrochemical polymerization with a 3.06 mA/$\textrm{cm}^2$ current density at 25 $^{\circ}C$ for 2 hrs with the separator plate. The surface resistivity of the resulting fabric was as low as 5 Ω/$\square$ .The PPy-coated fabric prepared under the optimum conditions showed practically applicable heat generating property. When electrical power was supplied to the fabric using a commercial battery for a mobile phone (3.6 V, LGLl-AHM), the temperature of the fabric increased very quickly from room temperature to ca. 55 $^{\circ}C$ within 2 min and was maintained for ca. 80 min at that temperature. The heat generating property of the fabric was extremely stable, exhibiting similar behavior over 10 repeated cycles. Therefore, we suggest that the PPy-coated fabric in this study may be practically useful for many applications, including flexible, portable surface-heating elements for medical or other applications.