Computational Model for End-On LCEs*

In main-chain liquid crystalline elastomers (LCE’s), and in side-chain LCE’s where mesogens are attached to the polymer backbone at their midpoint, the polymer chains comprising the elastomer align with the mesogens when they are in the nematic state. For the case of side-chain mesogens attached at one end, though, ordering of the mesogens can induce alignment of the polymer backbone either parallel or orthogonal to the nematic director. We incorporate a theory of side-chain LCE’s into a constitutive model for elastomers to describe these competing effects. We compare simulation results against experiment, and show how an end-on attachment scheme can create elastomers with bidirectional responses, meaning as temperature is varied, a single structure can be made to bend or twist in different directions. We anticipate that this can dramatically increase the possibilities for soft robotic systems.