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Intrinsic Tuning of Poly(styrene–butadiene–styrene)-Based Self-Healing Dielectric Elastomer Actuators with Enhanced Electromechanical Properties

Ellingford, Christopher; Zhang, Runan; Wemyss, Alan M.; Bowen, Christopher; McNally, Tony; Figiel, Łukasz; Wan, Chaoying

By 12 March 2019No Comments

ACS Applied Materials & Interfaces, 2018, vol 10, 44, pp. 38438-38448



The electromechanical properties of a thermoplastic styrene–butadiene–styrene (SBS) dielectric elastomer was intrinsically tuned by chemical grafting with polar organic groups. Methyl thioglycolate (MG) reacted with the butadiene block via a one-step thiol–ene “click” reaction under UV at 25 °C. The MG grafting ratio reached 98.5 mol % (with respect to the butadiene alkenes present) within 20 min and increased the relative permittivity to 11.4 at 103 Hz, with a low tan δ. The actuation strain of the MG-grafted SBS dielectric elastomer actuator was 10 times larger than the SBS-based actuator, and the actuation force was 4 times greater than SBS. The MG-grafted SBS demonstrated an ability to achieve both mechanical and electrical self-healing. The electrical breakdown strength recovered to 15% of its original value, and the strength and elongation at break recovered by 25 and 21%, respectively, after 3 days. The self-healing behavior was explained by the introduction of polar MG groups that reduce viscous loss and strain relaxation. The weak CH/π bonds through the partially charged (δ+) groups adjacent to the ester of MG and the δ- center of styrene enable polymer chains to reunite and recover properties. Intrinsic tuning can therefore enhance the electromechanical properties of dielectric elastomers and provides new actuator materials with self-healing mechanical and dielectric properties.

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