Synthesis, characterization and vapor sensing properties of a novel P(St–co–AN)/MWCNTs–VTES nanocomposite thin film as a gas sensor

Abstract Carbon nanotubes (CNTs) with excellent electrical conductivity have high sensitivity as the conductive part of polymer gas sensors, but their applications are limited because they are not easy to be coated by polymer. The surface treatment was employed to improve the dispersity and surface chemical reactivity of the hydroxyl–functionalized multi–walled carbon nanotubes (MWCNTs–OH) in this paper. Vinyl triethoxysilane (VTES) is attached or tailored onto the surface of MWCNTs–OH as a bridging reagent by means of a dehydration reaction between O Si groups on VTES and OH groups in the MWCNTs–OH. At last, VTES–functionalized MWCNTs–OH (MWCNTs–VTES) with C C double bond as the polymerization active point are chemical–covalently coated with the styrene–acrylonitrile copolymer (P(St–co–AN)) by an in situ dispersion polymerization route. Thus, vapor sensing films with intensive response to solvent vapors were assembled through an covalent or non–covalent interaction between MWCNTs–VTES and P(St–co–AN). The structure, chemically covalent interactions and morphological characterization were characterized and confirmed. The results show that MWCNTs are closely coated by P(St–co–AN) through strong covalent interaction, which improves the dispersion quality and compatibility of MWCNTs. The composite conducting film bears an expeditious response, favorable reversibility and reproducibility to some volatile organic solvent vapors, which were are believed to be closely related with an expansion effect and an interaction among carbon nanotubes, copolymers and solvent molecules. The vapor sensing properties well reveal that this material have a possibility as a candidate of volatile organic solvent vapor sensors.