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Thermosensitive properties of semi-IPN gel composed of amphiphilic gel and thermosensitive polymer in buffer solution

Authors

  • Atsushi Takahashi,

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    1. Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
    2. Yokohama Corporate Research Laboratories, Mitsubishi Rayon Co. Ltd., 10-1 Daikoku-cho, Tsurumi-ku, Yokohama 230-0053, Japan
    • Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
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  • Shuji Sakohara

    1. Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
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Abstract

In this study, a semi-interpenetrating polymer network (semi-IPN) gel comprising a crosslinked amphiphilic N,N-dimethylacrylamide-co-N-isopropylacrylamide gel and interpenetrating thermosensitive poly(N-isopropylacrylamide) (poly(NIPAM)) was prepared. Their thermosensitive behaviors in a buffer solution comprising sodium chloride, sodium citrate, and sodium dodecyl sulfate, which are generally used in biochips, were investigated. At low temperatures, the gel in the buffer solution was absolutely transparent. However, when the gel was heated, it became milky white or opaque without changes in the gel size. It is well known that the network or crosslink distribution of the transparent gel is homogeneous macroscopically, whereas that of the opaque gel is inhomogeneous; in other words, the network of the opaque gel consists of coarse and dense parts. The structural changes in the gel network were confirmed by the temperature dependence of the permeability of the buffer solution through the semi-IPN gel membrane. The permeability increased stepwise when the gel became opaque due to heating. The structural changes in the semi-IPN gel network depended on the compositions of the buffer solution and gel, i.e., the copolymerization ratio of NIPAM in the gel and the content of the poly(NIPAM) molecules in the gel. These results suggest that the thermosensitive behaviors of the semi-IPN gel strongly depend on the interactions between the copolymerized NIPAM in the gel network and the poly(NIPAM) molecules. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

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