Investigation on thermoresponsive behavior of biodegradable poly(γ-glutamic acid)-graft-L-phenylalanine ethyl ester

Authors

  • Amornrat Lertworasirikul,

    Corresponding author
    1. Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Ladyao, Chatuchak, Bangkok 10900, Thailand
    2. Center of Advanced Studies in Industrial Technology, Faculty of Engineering, Kasetsart University, Ladyao, Chatuchak, Bangkok 10900, Thailand
    • Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Ladyao, Chatuchak, Bangkok 10900, Thailand
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  • Nu-orn Choothong,

    1. Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Ladyao, Chatuchak, Bangkok 10900, Thailand
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  • Hiroaki Yoshida,

    1. Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka, 565-0871, Japan
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  • Michiya Matsusaki,

    1. Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka, 565-0871, Japan
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  • Toshiyuki Kida,

    1. Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka, 565-0871, Japan
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  • Apirat Laobuthee,

    1. Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Ladyao, Chatuchak, Bangkok 10900, Thailand
    2. Center of Advanced Studies in Industrial Technology, Faculty of Engineering, Kasetsart University, Ladyao, Chatuchak, Bangkok 10900, Thailand
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  • Mitsuru Akashi

    Corresponding author
    1. Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka, 565-0871, Japan
    • Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka, 565-0871, Japan
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Abstract

The thermosensitivity of biodegradable and non-toxic amphiphilic polymer derived from a naturally occurring polypeptide and a derivative of amino acid was first reported. The amphiphilic polymer consisted of poly(γ-glutamic acid) (γ-PGA) as a hydrophilic backbone, and L-phenylalanine ethyl ester (L-PAE) as a hydrophobic branch. Poly(γ-glutamic acid)-graft-L-phenylalanine (γ-PGA-graft-L-PAE) with grafting degrees of 7–49% were prepared by varying the content of a water-soluble carbodiimide (WSC). γ-PGA-graft-L-PAE with a grafting degree of 49% exhibited thermoresponsive phase transition behavior in an aqueous solution at around 80°C. The copolymers with grafting degrees in the range of 30–49% showed thermoresponsive properties in NaCl solution. A clouding temperature (Tcloud) could be adjusted by changing the polymer concentration and/or NaCl concentration. The thermoresponsive behavior was reversible. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

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