title: In situ prepared polypyrrole for low humidity QCM sensor and related theoretical calculation.
abstract: In situ preparation of polypyrrole (Ppy) by photo-polymerization coated on a quartz crystal microbalance (QCM) as a low humidity sensor was reported. Different concentrations of Ppy films say 0wt.% (as blank), 0.1, 1, and 10wt.% were investigated to measure humidity concentrations between 14.7 and 5412.5ppm(v). The adsorption/desorption behavior was also examined at humidity concentration 510.2ppm(v). The sensitivities of 0, 0.1 and 1wt.% Ppy films at 51.5ppm(v) were 0.143, 0.219 and 0.427, respectively. For 1wt.% Ppy, the highest sensitivity was obtained. The slope and correlation coefficients (R(2)) for 1wt.% Ppy at the ranges of 14.7-898.6ppm(v) were 0.0646 and 0.9909, respectively. A series of molecular simulations have been carried out to calculate bond energy for the water molecule interaction with Ppy, which was found to be approximately 3kcal/mol indicating the existence of hydrogen bonding during the sorption process. Based on Langmuir isotherm adsorption assumption, for 0.1 and 1wt.% Ppy films, the association constants were 2606.30 and 5792.98, respectively. This larger association constant for 1wt.% Ppy film explains higher sensitivity.
authors.affiliation: Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan, ROC.
authors.forename: Yi-Lu
authors.initials: YL
authors.lastname: Sun
authors.forename: Ren-Jang
authors.initials: RJ
authors.lastname: Wu
authors.forename: Yu-Ching
authors.initials: YC
authors.lastname: Huang
authors.forename: Pi-Guey
authors.initials: PG
authors.lastname: Su
authors.forename: Murthy
authors.initials: M
authors.lastname: Chavali
authors.forename: Yi-Zhen
authors.initials: YZ
authors.lastname: Chen
authors.forename: Chu-Chieh
authors.initials: CC
authors.lastname: Lin