Structure and Hydrolysis Activity of Poly(allylamine)s Having Hydrophobic Groups

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Other Title
  • 疎水性基をもつポリアリルアミンの構造特性とその加水分解活性

Description

Amphiphilic cationic polyelectrolytes were obtained by the chemical modification of poly(allylamine)(PAA) with long alkyl chains and benzyl groups. These polymers showed highly surface activity and had compact conformation in aqueous solutions. This indicated the appearance of rigid hydrophobic domains similar to micelles formed by simple surfactants. In the present work, the structural effect of the polymeric amphiphilies on the hydrolysis of p-nitrophenyl acetate were examined. N-Octylated PAA and N-ben zylated PAA exerted the larger accelerating effect on the reaction than PAA. The higher the degree of substitution (D. S. ), the lower is the polarity of the polymer domain, and the higher the hydrolysis activity. It was suggested that the acceleration is controlled mainly by the concentration effect, and the more compact micellelike structure provides the hydrophobic reaction field, effective in including the substrate. In the case of N-dodecylated PAA, the less polar microenvironment of polymer mice lle was shown clearly even at D. S. =0.12. And the PAA derivative of D. S.≠ O.2, which has the hydrophobicity of ET≠55 and lowest viscosity, exhibited the maximum catalytic activity. However, a higher D. S. decreased the rate of the hydrolysis; thus, the bulky dodecyl side groups are supposed to perturb the effective structure of the domain, resulting in the reduction of the capability to trap substrate molecules. On the other hand, the change in pH and the addition of ethanol or sodium chloride were found to influence the conformational structure of the polymers and their hydrolytic properties.

Journal

  • NIPPON KAGAKU KAISHI

    NIPPON KAGAKU KAISHI 1991 (8), 1115-1126, 1991-08-10

    The Chemical Society of Japan

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