QCM nanocomposite gas sensors - Expanding the application of waterborne polymer composites based on graphene nanoribbon

Graphene nanoribbons (GNR) are narrow strips of graphene in one dimensional morphology with extraordinary properties, owing to the large edges that offer numerous interfacial contact area to the polymer phase in the composite materials. Consequently, minor amount of GNR incorporated within polymer matrix, will not only reinforced mechanically and thermally the composite materials, but will significantly expand their application potential, giving added value to the cheap polymeric material. Herein, the quartz crystal microbalance (QCM) gas sensing of the nanocomposites was investigated. In this work we took advantage of the polymerization in dispersed media as green synthesis method to produce for first time waterborne polymer/GNR nanocomposites. The lack of aggregation during structuring of GNRs within the polymer matrix and the established covalent bonding between the polymer and GNRs phases were responsible for the observed strong mechanical and thermal reinforcement of the nanocomposites. By exposure of the nanocomposites to low concentrations of toxic gases (CO, NH3, and N2O in a concentration range of 70-1000 ppm), it was found that the sensors are characterized by a large sensor response in short time, at room temperature and with very good reproducibility in three investigated cycles of gas adsorption and desorption. The excellent performance was attributed to the large functional interface created between the GNRs and the polymer that offer numerous adsorption sites, along with the composite morphology that provide availability of these sites to the gasses. The sensors have shown selectivity towards NH3 rather than N2O and CO, likely, because the former interacted with the composite materials by joint Wan der Waals forces and hydrogen bonding, whereas the last two gasses interact exclusively by the van der Waals interactions.