High-Concentration Mesogen-Assisted Exfoliation of Low-Dimensional Nanomaterials for Achieving Ultralow-Temperature Actuations of Liquid Crystal Elastomers

초록

Soft robots are expected to operate in extreme environments such as polar regions or space, where human activities are severely limited. However, conventional thermo-responsive liquid crystal elastomers (LCEs), which are common actuators, are unable to function in freezing conditions as the phase transitions upon which they rely for their function occur at elevated temperatures. Here, the realization of LCE actuators is described with superior thermomechanical effects that can achieve high work output at −80 °C. The approach rests on the notion that LCE composites containing sufficiently large quantities of photothermal nanomaterials can reach transition temperatures upon light irradiation, even under extreme cold, thereby enabling actuation. To achieve this high loading, a simple yet universal mesogen-assisted exfoliation method is developed where mesogens directly exfoliate various low-dimensional nanomaterials, including MoS2. Due to the high concentration of MoS2 nanosheets, the mesogen-MoS2 composite exhibits remarkable photothermal effects, exhibiting local temperature increases of over 700 °C within 3 s. Such large photothermal responses enable the MoS2-containing LCE actuator to perform light-driven mechanical actuation at low ambient temperatures of −80 °C. Our strategy opens new possibilities for significantly lowering the temperature performance envelope of LCE-based soft actuators.

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