A Composite of Crosslinked and Quaternized Poly (4-vinylpyridine) and Polypyrrole as a Potential Candidate for the Detection of Low Humidity

<正>1 Results Despite rapid progress in the development of resistive-type humidity sensors, the detection of low humidity is still a problem[1, 2]. In this study, poly(4-vinylpyridine) was crosslinked and quaternized with 1,4-bromobutane to form a polyelectrolyte humidity sensitive film on interdigitated gold electrodes, which was further coated with a layer of polypyrrole by a facile method of vapor phase polymerization process. The composite so prepared was characterized by UV-vis spectroscopy and scanning electron microscopy. It was found that the impedance of the composite changed linearly with humidity in the range of 0～60%RH with good sensitivity. In addition, it exhibited a fast response (t90%: ≈33 s and ≈110 s for adsorption and desorption, respectively) and a relative small hysteresis (≈5%RH). The effect of concentration and ratio of oxidizing agent and dopingagent, temperature of vapor phase polymerization of pyrrole on the humidity sensitive properties of the composite have been investigated. The sensitive mechanism of the composite was also explored. The composite of conducting PPy and polyelectrolyte has great potential as a candidate sensitive material forlow humidity detection.