Article ID Journal Published Year Pages File Type
5186131 Polymer 2007 14 Pages PDF
Abstract

We have used DSC, FTIR spectroscopy, and ac impedance techniques to investigate the interactions that occur within complexes of poly(vinylpyrrolidone-co-methyl methacrylate) (PVP-co-PMMA) and lithium perchlorate (LiClO4) as well as these systems' phase behavior and ionic conductivities. The presence of MMA moieties in the PVP-co-PMMA random copolymer has an inert diluent effect that reduces the degree of self-association of the PVP molecules and causes a negative deviation in the glass transition temperature (Tg). In the binary LiClO4/PVP blends, the presence of a small amount of LiClO4 reduces the strong dipole-dipole interactions within PVP and leads to a lower Tg. Further addition of LiClO4 increases Tg as a result of ion-dipole interactions between LiClO4 and PVP. In LiClO4/PVP-co-PMMA blend systems, for which the three individual systems-the PVP-co-PMMA copolymer and the LiClO4/PVP and LiClO4/PMMA blends-are miscible at all compositional ratios, a phase-separated loop exists at certain compositions due to a complicated series of interactions among the LiClO4, PVP and PMMA units. The PMMA-rich component in the PVP-co-PMMA copolymer tends to be excluded, and this phenomenon results in phase separation. At a LiClO4 content of 20 wt% salt, the maximum ionic conductivity occurred for a LiClO4/VP57 blend (i.e., 57 mol% VP units in the PVP-co-PMMA copolymer).

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Physical Sciences and Engineering Chemistry Organic Chemistry
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