Synthesis and Humidity Sensitive Properties of Pyrrole-Based Polyelectrolytes

Pyrrole (Py)-based polyelectrolytes (Py-PE): P(Py-COOLi), P(Py-COONa), and P(Py-COOK) was synthesized, characterized, and used to prepare thin film resistive humidity sensors. Their humidity sensitive properties have been investigated, and sensing mechanism was presented. The Py-PE contains PPy as backbone and the side chain bearing carboxylic salt group, which made its sensor exhibited a very wide humidity sensing range of 0-97%, relative humidity (R-H), high conductivity even at very low humidity, and both ionic and electronic conduction contributed to its conductivity. Among all the Py-PE, P(Py-COOK) showed high sensitivity, with the impedance changing of about three orders of magnitude (10(3)-10(6) Omega) from 97 to 0% RH, whereas P(Py-COONa) showed quick response for both absorption (12.5 s) and desorption (15.2 s). Py-PE prepared is promising for preparation of thin film resistive humidity sensors capable of detecting low humidity. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 1287-1293, 2009