Properties of PDMS-divinylbenzene based pre-concentrators for nitroaromatic vapors

Abstract

Pre-concentrators are used to improve the detection of analytes that are at low concentration, particularly in air. Polymeric materials are the basis for most pre-concentrators and a strategy to enhance the pre-concentration capability is to add moieties that enhance the polymer matrix–analyte interaction. In this study, the sorption capability of poly(dimethylsiloxane) (PDMS)-based pre-concentrator films towards nitro-based explosives was improved by incorporating a 1,4-divinylbenzene (DVB) derived component. It was found that the mode of DVB incorporation strongly influenced the structure and pre-concentration properties of the resulting film. Films formed from blends of PDMS and DVB (PDMS:DVB) were found to have similar sorption properties as PDMS. The copolymerised (PDMS-co-DVB) film was found to be comprised of voids and spheroidal features, which were retained even after thermal treatment. The copolymer film offered the greatest sorption and retention of analyte vapor, which we attribute to increased material surface area and π–π interactions between the DVB-derived units and the nitroaromatic analytes. The copolymerised film was able to increase the effective concentration of TNT vapor by 3 orders of magnitude relative to the headspace vapor concentration.