High-Strain Shape-Memory Polymers

Authors

  • Walter Voit,

    Corresponding author
    1. School of Materials Science and Engineering Georgia Institute of Technology 771 Ferst Drive, Atlanta, GA 30332 (USA)
    • School of Materials Science and Engineering Georgia Institute of Technology 771 Ferst Drive, Atlanta, GA 30332 (USA).
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  • Taylor Ware,

    1. School of Materials Science and Engineering Georgia Institute of Technology 771 Ferst Drive, Atlanta, GA 30332 (USA)
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  • Raghunath R. Dasari,

    1. School of Chemistry and Biochemistry Georgia Institute of Technology 901 Atlantic Drive, Atlanta, GA 30332 (USA)
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  • Paul Smith,

    1. School of Materials Science and Engineering Georgia Institute of Technology 771 Ferst Drive, Atlanta, GA 30332 (USA)
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  • Lauren Danz,

    1. School of Materials Science and Engineering Georgia Institute of Technology 771 Ferst Drive, Atlanta, GA 30332 (USA)
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  • Dustin Simon,

    1. School of Materials Science and Engineering Georgia Institute of Technology 771 Ferst Drive, Atlanta, GA 30332 (USA)
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  • Stephen Barlow,

    1. School of Chemistry and Biochemistry Georgia Institute of Technology 901 Atlantic Drive, Atlanta, GA 30332 (USA)
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  • Seth R. Marder,

    1. School of Chemistry and Biochemistry Georgia Institute of Technology 901 Atlantic Drive, Atlanta, GA 30332 (USA)
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  • Ken Gall

    Corresponding author
    1. School of Materials Science and Engineering Georgia Institute of Technology 771 Ferst Drive, Atlanta, GA 30332 (USA)
    2. Woodruff School of Mechanical Engineering Georgia Institute of Technology 771 Ferst Drive, Atlanta, GA 30332 (USA)
    • Woodruff School of Mechanical Engineering Georgia Institute of Technology 771 Ferst Drive, Atlanta, GA 30332 (USA).
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Abstract

Shape-memory polymers (SMPs) are self-adjusting, smart materials in which shape changes can be accurately controlled at specific, tailored temperatures. In this study, the glass transition temperature (Tg) is adjusted between 28 and 55 °C through synthesis of copolymers of methyl acrylate (MA), methyl methacrylate (MMA), and isobornyl acrylate (IBoA). Acrylate compositions with both crosslinker densities and photoinitiator concentrations optimized at fractions of a mole percent demonstrate fully recoverable strains at 807% for a Tg of 28 °C, at 663% for a Tg of 37 °C, and at 553% for a Tg of 55 °C. A new compound, 4,4′-di(acryloyloxy)benzil (referred to hereafter as Xini) in which both polymerizable and initiating functionalities are incorporated in the same molecule, was synthesized and polymerized into acrylate shape-memory polymers, which were thermomechanically characterized yielding fully recoverable strains above 500%. The materials synthesized in this work were compared to an industry standard thermoplastic SMP, Mitsubishi's MM5510, which showed failure strains of similar magnitude, but without full shape recovery: residual strain after a single shape-memory cycle caused large-scale disfiguration. The materials in this study are intended to enable future applications where both recoverable high-strain capacity and the ability to accurately and independently position Tg are required.

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