Novel optical sensors for detection of nitroaromatics based on supported thin flexible poly(methylhydrosiloxane) permeable films functionalised with silole groups

A new silole bearing an allyl group at silicon has been incorporated into previously-reported novel reactive polysiloxane coatings made from polymethylhydrosiloxane (PMHS) polymers crosslinked by the sol-gel process allowing subsequent functionalization by hydrosilylation of the SiH reactive groups. The thin films of crosslinked resin are covalently bonded to the glass substrate and contain a very low concentration of silole groups. They exhibit the aggregation-induced emission effect owing to restricted intramolecular rotation, and show enhanced sensitivity to nitroaromatic analytes because of the very low concentration of silole groups. The films can be used to test for nitroaromatics present not only in the vapour phase but also in many types of solvent because of the robust nature of the crosslinked network and covalent bonding to the substrate. They can be made in thicknesses ranging from 20 nm up to 1 μm. The silole groups are readily accessible, and the sensors can be regenerated by washing with solvents such as chloroform.