Topology-Driven Mechanical Behavior of Liquid Crystal Elastomers via a Dynamic Mechanical Analyzer

Traditional vitrimers are cross-linked materials with plasticity that can be reprogrammed through transesterification reactions. To impart shape memory functionality to vitrimers, this study employed liquid crystal monomers and synthesized a series of reprogrammable shape-memory elastomers via Michael addition. To understand how a material deforms under sinusoidal stress and to measure the resulting strain, a dynamic mechanical analyzer (DMA) was employed to investigate the viscoelastic behavior of the synthesized materials. By analyzing their response to periodic stress, key mechanical properties were determined. DMA and thermal actuation tests revealed the phase transition characteristics of the elastomer. Stress relaxation experiments revealed that the synthesized liquid crystal elastomers (LCEs) exhibited significant stress relaxation behavior at 80 °C. Furthermore, when the LCEs were heated to 80 °C without applied stress, their molecular alignment decreased. The characteristic properties of the liquid crystal elastomers, as well as the thermal actuation behavior of the synthesized 5LCE film, were further confirmed via these analyses.