Conductive washable wool textiles: Evaluating graphene oxide coating methods

Application of graphene oxide (GO) on textiles is a broadly practised method to produce electrically conductive textiles. GO coating is commonly done using two methods, i.e., consecutive coating cycles followed by reduction (CC), and coating-reduction in a cyclic order (CR). Despite the former consuming less time, energy and chemicals, both methods are still equally practised as their comparative outcome on the final conductivity is not known. Knowledge is also limited on the use of GO towards protein fibres, particularly on wool despite being the leading animal fibre. This study is the first example of GO application exclusively onto pure wool. Pioneering in the literature, it also demonstrates the comparative effectiveness of the two major GO coating methods. Nonwoven and knitted wool fabrics were used as the substrates and their structural influences were also discussed. Results showed that the CC method was significantly more effective than the CR method regarding GO addition and delivering superior conductivity in a quicker time (1.07 S m-1 after 6 cycles). Nonwoven fabrics were more favourable for the coating process compared to knitted fabric. The coated fabrics were washable and conductivity was found stable for up to 2 months with no significant change. A lower surface density (220 g/m2) wool nonwoven was able to generate 50 degrees C temperature by 12 V connection. Overall, this study reveals the potential of GO-coated wool for useful applications including heating pads and automotive seat warming, while concludes the CC method as a remarkably better way of coating than the CR method.