FTIR imaging applied to polymer systems

This study employs FTIR imaging for the characterization of various polymer systems. First, the diffusion and dissolution of poly(vinyl acetate) in binary non-solvent mixtures of ethanol and water was examined. The results of this study showed that certain combinations of these two non-solvents act synergetically to function as a good solvent for the polymer. Initial diffusion rates were calculated from the concentration profiles, which showed a positive deviation from ideal behavior. Moreover, the spectral data indicated that ethanol and water form a hydrogen-bonded complex that enables these non-solvents to dissolve the polymer.; FTIR imaging was subsequently explored for the characterization of controlled-release drug applications, where nicotine/ethanol/water solutions were diffused into ethylene-vinyl acetate membranes as a model transdermal-type delivery system. The spatial distribution of the components, membrane swelling, diffusion rates and characteristics, and component interactions were determined, and these results demonstrated that FTIR imaging offers unique information that is important for the characterization of transdermal drug delivery systems.; Next, FTIR imaging was used to study the potential of crosslinked polymers for use as chemical sensors. The results illustrated that FTIR imaging is effective for visualizing the patterning of the crosslink density of a polymer film as well as the temporal and spatial sorption patterns of different solvent vapors. The FTIR images also showed that the decrease in sorption capacity with crosslink density is solvent-specific, which suggests that photocrosslinkable polymers can be used to reduce the number of raw materials needed to create a chemical sensor array.; Finally, the factors that influence the IR absorbance of nematic liquid crystals and their consequences on FTIR imaging were demonstrated and discussed. It was shown that ordering and alignment, as well as concentration affect the FTIR images of nematic liquid crystals in a polymer matrix. The extent of the ordering and alignment effects was then demonstrated in the first FTIR images of the nematic to isotropic transition of E7 liquid crystals.