SM01.03.26 : 4D Printing of Liquid Crystal Elastomers

5:00 PM–7:00 PM Apr 3, 2018 (America - Denver)

PCC North, 300 Level, Exhibit Hall C-E

Cedric Ambulo1 Taylor Ware1

1, The University of Texas at Dallas, Richardson, Texas, United States

Three-dimensional structures capable of reversible changes in shape, i.e. 4D printed structures, may enable new generations of soft robotics, implantable medical devices, and consumer products. Here, thermally-responsive liquid crystal elastomers (LCEs) are direct-write printed into 3D structures with controlled molecular order. Molecular order is locally programmed by the shear associated with extrusion, with the order following the print path used to build the 3D object. This order controls the stimulus response. Locally, each aligned LCE filament undergoes a 40% reversible contraction along the print direction on heating. However, this combination of controlled geometry and stimulus response in 3D enables the manufacture of objects capable of shape transformations that are atypical for this class of materials. For example, porous scaffolds can be designed to undergo reversible volumetric contraction on heating despite the isochoric nature of the stimulus response in LCEs. Furthermore, we demonstrate that by printing shells with regions of both positive and negative Gaussian curvature, actuators that undergo rapid, repetitive snap-through transitions, can be realized. Finally, we will discuss expanding the use of this printing technique to a variety of liquid crystal inks, enabling fabrication of light and humidity responsive 3D structures.