Thermomechanical Actuator Based on a Molecular-Spring Polymer with a Long Alkyl Side Chain
journal contributionposted on 30.06.2020 by Sang-Hoon Kang, Young-Jae Jin, Giseop Kwak
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A disubstituted acetylene polymer, with a molecular-spring main chain and a long alkyl side chain of the octadecyl group (PDMC18SP), was examined as an active material for a thermomechanical actuator and its thermodynamic and (thermo)mechanical properties were compared to those of other two polymer derivatives [i.e., a polymer without a long alkyl side chain (PTMSP) and a polymer with the same long alkyl side chain with a phenyl ring (PDMC18SDPA)]. Unlike PTMSP, PDMC18SP and PDMC18SDPA produced soft films, which could be considerably elongated by an external tensile force at room temperature. When the external force was removed, PDMC18SP recovered to its original form, while PDMC18SDPA did not. Both polymers showed apparent thermodynamic phase transition. PDMC18SP underwent a much greater change under both strain and stress with temperature compared to PDMC18SDPA. PDMC18SP was used as an active layer to prepare a bilayer-type actuator, which showed apparent mechanical actuation with temperature. The direction of mechanical actuation was easily controlled by shearing the active layer.