Synthesis and characterization of polypyrrole grafted cellulose for humidity sensing

The present communication reports the synthesis of polypyrrole-grafted-cellulose (PPy-g-Cellu) copolymer by a chemical method at ambient condition. The representative samples of PPy-g-Cellu were characterized using infra red spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), UV-vis spectroscopy (UV-vis) and themogravimetry (TG) techniques. The prepared copolymer was crystalline in nature with improved thermal stability. Further, electrical properties reveals the formation of polypyrole grafted cellulose copolymer with 10(7) fold improved electrical conductivity and 10(2) folds hydrophillcity than cellulose and polypyrrole, respectively. The electrical resistance of a PPy-g-Cellu film casted on a glass substrate was measured as function of relative humidity in the range of 5-95% to explore its use for humidity sensing purposes. Finally, PPy-g-Cellu offers a promising perspective as a humidity sensing material with response time 25 s, recovery time 20 s and stability for 40 days.