Evaluating Polymeric Materials for Sensing of Gaseous Analytes

Abstract

Polymers have been widely used in gas sensing applications especially for detecting Volatile Organic Compounds (VOCs). Some of these applications consist of disease diagnosis and breathalyzers as well as evaluation of indoor air quality and detecting toxic analytes. A sensing material requires to be highly sensitive to small amounts of gas. Selectivity is another essential characteristic, which has to be evaluated since many vapours/gases exist in small quantities (ppm or ppb) in houses and work places at the same time. The goal was to evaluate poly (methyl methacrylate) doped with metal oxides as a potential sensing material for detecting acetone (diabetic applications). Afterwards, other polymeric sensing materials were examined for gas sorption capabilities toward formaldehyde, acetaldehyde, and benzene. The experiments were all operated at room temperature through a highly specialized and sensitive Gas Chromatograph test system. Polyaniline (PANI), poly (2,5-dimethyl aniline) (P25DMA), poly(4-vinyl phenol) (P4VP), and poly (acrylic acid) (PAAc) have also been investigated as potential sensing material for formaldehyde sorption. After selecting the promising sensing material in single gas evaluations, selectivity of each sensing material has been studied. In order to evaluate selectivity, the target analyte has to be in a mixture with interferents (other gas analytes). Benzene and acetaldehyde were chosen as interferent analytes. Several gas concentrations and gas mixture ratios have been investigated to have a complete set of experiments and comparable data. In addition, one of the promising sensing materials for formaldehyde detection, PANI, was doped with NiO and In2O3 to further evaluate whether metal oxides can enhance sensing capabilities. At the final characterization step, Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) were used for additional information about the topology and the composition of the polymeric samples as well as incorporation of metal oxides into polymers.