Hydrogen-bond acidic organic compound-sensitized ionic gel for dimethyl methylphosphonate detection

Due to the threat of chemical warfare agents (CWAs), there is a pressing need to develop miniaturized gas sensors with fast response, high sensitivity and good stability. Herein, hexafluoroisopropanol aniline (HFIPA), a hydrogen-bond acidic organic compound, is embedded into a cross-linked poly(ethylene glycol) diacrylate/ionic liquid (PEGDA/IL) matrix as a sensitive film for detecting sarin simulant dimethyl methylphosphonate (DMMP). We find that the IL in the film constructs efficient gas transport channels, improving the absorption-desorption kinetics of DMMP molecules. The introduction of HFIPA enhances selectivity and sensitivity to DMMP through hydrogen bonding interaction. As a result, the SAW gas sensor based on PEGDA/IL-HFIPA ionic gel exhibits a fast response/recovery time of 28/53 s to 20 ppm DMMP and a low detection limit of 0.2 ppm at room temperature. By comparing with PEGDA-HFIPA, PEGDA/IL-HFIPA shows excellent anti-humidity interference ability, which is also attributed to the stable gas transport channels constructed by IL. Overall, this work develops a novel strategy to improve the gas-sensing properties of organic polymer materials.