Assembly of Cu nanoparticles in a polyacrylamide grafted poly(vinyl alcohol) copolymer matrix and vapor-induced response

A vapor-sensitive electroconductive film was designed and assembled by inserting Cu²⁺ particles into a polyacrylamide grafted poly(vinyl alcohol) (PAM-g-PVA) in virtue of a complexation between Cu²⁺ and PVA even PAM, as well as the establishment of inter- and intramolecular attractions between polymer matrices, which were in turn reduced into Cu nanoparticles by sodium hypophosphite as a reducing agent. The PAM-g-PVA graft copolymer was prepared via a simple free radical polymerization reaction initiated by a redox reaction. The resistance responsiveness of the film samples to various organic vapor surroundings was investigated. The responsive magnitude, response time and recovery properties depend on the molecular weight of the graft polymer or the PAM chain length and initial resistances of the film samples or Cu particle contents upon exposed to ether and petroleum ether vapor, etc. The structure and morphologies of the PAM-g-PVA/Cu were characterized by a Fourier transform infrared spectroscope and a transmission electron microscope. The response mechanism of the PAM-g-PVA/Cu films to solvent vapors was accounted for by a swelling theory and an interaction between solvent vapor molecules and nanocomposites as well as the type and strength of interaction that each solvent vapor exhibits on the material.