Morphing Surfaces formed by Liquid Crystal Elastomer Coatings: Design and Modeling*

The suction cups on the arms of an octopus are morphing structures that can actuate to adhere to a non-porous surface, and then release on command. To mimic this functionality in an engineered material, we design and model dynamically morphing surface coatings composed of stimuli-responsive liquid crystal elastomers (LCE). In these programmable materials, patterned molecular orientation gives rise to complex shape transformations, driven by change of temperature. Using a combination of Finite Element Modeling (FEM) and analytical calculations, we design and characterize director patterns that create a variety of surface topographies: a lattice of spikes and/or indentations, an array of parallel microchannels or ridges, and patterned zones of positive and negative Gaussian curvature. To drive a thin film coating to morph into a lattice of suction cup-like indentations, we design an LCE with an array of topological defects, where the orientation of the director near each defect core follows a sigmoid function. By tuning adjustable parameters that define the structure of the defect core, we control the resulting surface topography.