Structural and morphological characterizations of MWCNTs hybrid coating onto cotton fabric as potential humidity and temperature wearable sensor

- Functionalized MWCNTs, dispersed in a paste, were immobilized on cotton textile.
- Paste additives preserves the electrical conductivity of the MWCNTs.
- f-MWCNTs polymeric network shows a porous structured film able to absorb humidity molecules.
- f-MWCNTs based coating shows a sensing ability for concurrent humidity and temperature variations.
- Significant detection ranges were observed between 75 and 90% (RH%) and 10-20 °C (T/°C).

A new Multi-Walled Carbon Nanotubes (MWCNTs) based conducting cotton fabric was properly designed and achieved, as a useful component for the development of humidity and temperature sensors. A synthetic strategy was optimized through subsequent steps of MWCNTs functionalization and dispersion in a polymer matrix, by first reacting functionalized MWCNTs, 1,2,3,4-butanetetracarboxylic acid (BTCA), polyvinyl alcohol (PVA), and then adding a polyacrylic resin. The polymeric paste thus obtained, containing a synthetic thickener, was applied by a knife-over-roll coating technique onto cotton fabric, then dried and finally cured. The polymeric coated textile sample was analyzed with different chemical-physical techniques to determine its morphological features, thermal behavior and surface resistance. Changes in surface resistance of the film were monitored as a function of relative humidity and temperature variation. The electrical resistance properties of the film deposited on cotton surface seem to be clearly influenced by the presence of water molecules interacting with MWCNTs junctions. This efficient functional fabric may be a helpful starting point to develop technical textiles, or the component of a humidity sensor, useful as dual-functional sensing material for detection of environmental humidity/temperature variations.

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