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Crystallization‐Directed Anisotropic Electroactuation in Selectively Solvated Olefinic Thermoplastic Elastomers: A Thermal and (Electro)Mechanical Property Study
Author(s) -
Armstrong Daniel P.,
Spontak Richard J.
Publication year - 2018
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201803467
Subject(s) - materials science , thermoplastic elastomer , elastomer , anisotropy , isotropy , polymer , crystallization , mechanical energy , dielectric elastomers , fabrication , copolymer , thermal , thermoplastic , supramolecular chemistry , composite material , chemical engineering , crystal structure , crystallography , thermodynamics , medicine , power (physics) , chemistry , physics , alternative medicine , pathology , quantum mechanics , engineering
Dielectric elastomers (DEs), a class of soft electroactive polymers that change size upon exposure to an external electric field, constitute an increasingly important class of stimuli‐responsive polymers due primarily to their large actuation strains, facile and low‐cost fabrication, scalability, and mechanical robustness. Unless purposefully constrained, most DEs exhibit isotropic actuation wherein size changes are the same in all actuation directions. Previous studies of DEs containing oriented, stiff fibers have demonstrated, however, that anisotropic actuation along a designated direction is more electromechanically efficient since this design eliminates energy expended in nonessential directions. To identify an alternative, supramolecular‐level route to anisotropic electroactuation, we investigate the thermal and mechanical properties of novel thermoplastic elastomer gels composed of a selectively solvated olefinic block copolymer that not only microphase‐separates but also crystallizes upon cooling from the solution state. While these materials possess remarkable mechanical attributes (e.g., giant strains in excess of 4000%), their ability to be strain‐conditioned enables huge anisotropic actuation levels, measured to be greater than 30 from the ratio of orthogonal actuation strains. This work establishes that crystallization‐induced anisotropic actuation can be achieved with these DEs.