Conductive graphite nanoplatelets (GNPs)/polyethersulfone (PES) composites with inter-connective porous structure for chemical vapor sensing

Conductive polymer composites (CPCs) are good candidates as chemical vapor sensors. However, it is still challenging to develop CPC-based vapor sensors with low percolation thresholds and excellent sensing property (for example, high response intensity, low detection limit and good recyclability). Herein, electrically conductive and porous graphite nanoplatelets (GNPs)/polyethersulfone (PES) composites were prepared using vapor induced phase separation (VIPS) and freeze drying. VIPS was not only responsible for forming the inter-connective porous structure but also promoting the distribution of GNPs on the surfaces of PES skeletons, yielding a low percolation threshold of 0.52 wt%. When the conductive composites were used to detect chemical vapors, the response rate and vapor sensing intensity were controlled by the vapor pressure and the solubility parameters of solvent and polymer. It was found that the response intensities of the composites for saturated vapors of dichloromethane, acetone, tetrahydrofuran and ethanol were ~8.4 × 10³, 5.6 × 10², 10.3 and 3.5, respectively. The detection limit for acetone vapor was as low as 30 ppm. Excellent recyclability for the conductive composites as a chemical vapor sensor was also achieved.