Selective detection of trace p-xylene by polymer-coated QCM sensors

Two types of polymer-coated QCM sensors were developed, which exhibited high sensitivity, stability and selectivity for the detection of trace p-xylene vapor in air over toluene, butyl acetate and 1-butanol, which are usually produced in the coating process of films on the back of solar cell array. The polymers were poly(4-vinylbenzyl chloride) (PVBC) and poly(4-vinylbenzyl chloride-co-methyl methacrylate) (P(VBC-co-MMA)), respectively. Both PVBC and P(VBC-co-MMA)-coated QCM sensors were reusable and can be reactivated by releasing the adsorbed vapor in vacuum. The QCM data also indicated that the incorporation of MMA can enhance the sensitivity of the polymer-coated QCM sensor toward p-xylene vapor. The lowest detection limit can reach 54 ppm for the QCM sensor coated with 119 nm thick P(VBC-co-MMA) thin film, leading to the frequency shift of 9.6 Hz (−ΔF3). These two types of polymer-coated QCM sensors may find potential application in the monitoring and controlling the concentration of p-xylene vapor in the coating process of thin films on the back of solar cell array, ensuring the health of the related personnel in the factory of solar cell array.