Synthesis of polyaniline grafted cellulose suitable for humidity sensing

Abstract

Polyaniline-grafted-cellulose (PANi-cellulose) copolymer is prepared by a chemical method using cupric sulphate as initiator. The representative PANi-cellulose samples are characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric differential thermal analysis (TG-DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The data reveal the formation of electrically conducting and hydrophillc copolymer. The film of PANi-cellulose is casted on a glass slide by spin coating technique and used for humidity sensing of a controlled humid environment by monitoring electrical resistance. The resistance continuously decreased from ~ 32 MΩ to 10.0 MΩ with increase in relative humidity in the range of 5- 90%. The observed sensing parameters are sensitivity 0.22, response time 40 s, recover time 60 s and stability for more than 60 days.