Self-assembly of single walled carbon nanotubes onto cotton to make conductive yarn

A simple, economical and scalable technique is demonstrated to make conductive yarn. Single walled carbon nanotubes (SWCNTs) are non-covalently functionalized with dye (Acid Red 91) and dispersed in water; while cotton yarn is treated with poly (ethylene imine). When the resulting yarn is immersed in the SWCNT dispersion, SWCNTs self-assemble onto the yarn due to electrostatic forces between the functionalized nanotubes and yarn. Scanning electron microscopy, transmission electron microscopy and Raman spectroscopy indicate the assembly of carbon nanotubes. The SWCNT functionalized yarn exhibits reasonable electrical conduction behaviour and are then used to make chemiresistors. The electrical resistance of the chemiresistors used as sensors increases on exposure to ammonia gas, which can be explained in terms of electron transfer between gas molecules and SWCNTs. (C) 2012 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.