Synthesis of Poly(N-isopropylacrylamide) Gel and Core-Shell Type Gel with Thermo-Sensitive Shell Layer by Amidation of Poly(acrylic acid) Gel.

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  • Iizawa Takashi
    Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University
  • Matsuno Naoki
    Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University
  • Takeuchi Masashi
    Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University
  • Matsuda Fumihiko
    Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University

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Description

To synthesize a novel gel capsule containing a thermo-sensitive shell and hydrophilic core portions, we investigated the amidation of poly(acrylic acid) (AA) gel–1,8-diazabicyclo[5,4,0]undec-7-ene salt (DAA) with isopropylamine (IPA). The reaction of DAA with IPA proceeded almost quantitatively in NMP in the presence of triphenylphosphine (TPP). However, the amidation took place in competition with the esterification to give a copolymer of N-isopropylacrylamide with phenyl acrylate. The selectivity of amidation increased with increasing the IPA concentration although the observed decreasing rate of unswollen part was independent of the concentration. When the reaction was carried out at 1.0 mol L-1 of the IPA concentration in NMP, the amidation from the outside took place almost selectively to give poly(N-isopropylacrylamide) gel through a DAA-NIPA type gel capsule consisting of a hydrophilic unreacted core part and amidated shell layer. The swelling of the gel capsule and release of Methyl Orange from the gel capsule were studied. Above the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide) gel, the gel capsule swelled as well as DAA, and the shell layer did not work as a permeability barrier of water. However, an AA-NIPA type gel capsule containing a AA core part and thermo-sensitive shell layer, which was prepared from the neutralization of DAA-NIPA type gel capsule, showed on-off chemical release in response to stepwise temperature changes cross the LCST.

Journal

  • Polymer Journal

    Polymer Journal 34 (2), 63-71, 2002

    The Society of Polymer Science, Japan

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