Approaches for the synthesis, fabrication, and processing of responsive materials that integrate robust mechanical properties and reversible multiple stimuli responsibilities are of considerable interest. Liquid crystal elastomers (LCEs) are well-known for large strain and thermally-induced reversible shape change. However, the engineering applications of LCEs are often limited by the poor mechanical properties (strength, modulus, toughness) and the low actuation stress as compared to other engineering polymers and actuators. Furthermore, the biomedical applications of these shape-morphing materials are significantly restricted by harsh ques of actuation triggering such as high temperatures. To overcome these two significant limitations, weak mechanical properties and harsh actuation triggers, we describe systems of LCEs that exhibit robust mechanical properties and the high work capacities by introducing crystallinity in LCEs. Notably, crystallized LCEs exhibit moduli two orders of magnitude higher and toughness five times higher than nematic elastomers (<b>Figure 1</b>). These LCEs are capable of high load bearing during actuation, up to 1.3 MPa, and high work capacity, up to 730 kJ/m<sup>3</sup>. Moreover, we demonstrate various bio-friendly actuation stimuli sources such as visible light and electricity by synthesizing LCE nanocomposites. We believe that these approaches for the synthesis, fabrication, and processing of LCEs, which integrate advantages of semi-crystallinity, liquid crystallinity, and nanomaterials, provide promising solutions to improve performance of smart materials for both engineering and biomedical applications.

Tough and multi-stimuli responsive liquid crystal elastomers

254th National Meeting (2017)

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