Interaction of volatile organic vapours with azo-calix[4]-resorcinarene and poly(9-vinylcarbazole) thin films using SPR measurements

Thin films of azo-calix[4]resorcinarene (AZO) and poly(9-vinylcarbazole) (PVK) have been deposited by the method of spin coating and are studied for the optical detection of volatile organic vapour molecules. Both types of films were exposed to a range of concentrations of the vapours of benzene, toluene, n-hexane, m-xylene, and 1-butanol, and films' interaction with the above molecules was monitored using surface plasmon resonance (SPR) method. The films optical parameters change as a result of such interaction; these changes were determined from the theoretical data fitting of the measured SPR curves. The reflection intensity was also monitored as a function of time at a fixed angle of incidence near the reflectivity minima of the SPR curves. Mechanism of interaction with the studied vapour molecules is discussed in terms of capillary condensation of the vapour molecules inside the nanoporous matrix of PVK and AZO films. The films' responsivity is found to correlate with the solubility of AZO and PVK molecules in the above solvents.