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Importance of bound water in hydration-dehydration behavior of hydroxylated poly(N-isopropylacrylamide).

Abstract

In this study, a differential scanning calorimetric analysis was performed to investigate the role of water existing around the polymer chains on their thermoresponsive behaviors using the novel functional temperature-sensitive copolymer, poly(N-isopropylacrylamide-co-2-hydroxyisopropylacrylamide) (poly(NIPAAm-co-HIPAAm)). The HIPAAm comonomers were incorporated into the polymeric chains as hydrophilic parameters, and then the hydration states of poly(NIPAAm-co-HIPAAm) with various HIPAAm compositions were examined. Bound water, which is affected by the polymeric chains to some extent, was produced by adding the copolymers to the water, and the temperature due to the melting of the bound water decreased as the HIPAAm content increased. On the basis of this result, we considered that the interaction between the bound water and the polymeric chains is reinforced by the increasing HIPAAm composition. In addition, the cloud points of the copolymers shifted to a higher temperature, and the endothermic enthalpy for the phase transition decreased with increasing the HIPAAm content, suggesting that the number of water molecules disassociated from the polymeric chains decreased. Based on these results, we postulate that the changes in the interaction between the thermosensitive polymer and bound water exert a strong influence on its phase transition and/or separation, such as the cloud point or dehydration behavior.

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  • Authors

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    Source

    Journal of colloid and interface science 302:2 2006 Oct 15 pg 467-74

    MeSH

    Acrylamides
    Calorimetry, Differential Scanning
    Molecular Structure
    Phase Transition
    Sensitivity and Specificity
    Solutions
    Surface Properties
    Temperature
    Water

    Pub Type(s)

    Journal Article

    Language

    eng

    PubMed ID

    16887131