Shape Changing of Responsive Elastomer Structures

Project Overview

In this study, we explored the feasibility of direct ink write (DIW) printing liquid crystal elastomer (LCE) structures and inducing shape change using temperature and light stimuli. The induced shape change in the three-dimensional (3D) lattice structures would result in a change in porosity, mechanical properties, and wetting behavior with relevant applications in mechanical metamaterials, microscale mechanical logic gates, and lattice microfluidics, etc. ANSYS simulations of porosity change as a function of road width matched that of experimental values, reaching an upper pore size change of 73% and an overall volumetric change of 9%. Increased compression moduli of 60% were simulated before and after shape change in DIW-printed LCE lattices. Tight control of ink formulation enabled demonstration of the highest aspect ratio-printed LCE structure (44 layers) to our knowledge. Further formulation of a liquid crystal oligomer ink allowed successful incorporation of gold nanorods for future light-induced localized shape change in lattices.

Mission Impact

This project fits within the context of developing additive manufacturing of sentient materials with programmed responses. The force produced by the LCEs could be used to actuate microscale mechanical logic gates. In addition, there is interest at the High Explosives Applications Facility to develop high-strength elastomers with high solids loading capability. Porosity and other shape changes, particularly with spatial control, are of interest to various programs. For example, an LCE antenna can be reconfigured to different lengths to alter the resonance frequency. In addition, this project established a collaboration with the group of Professor Shu Yang at the University of Pennsylvania and this relationship will be continued in her upcoming National Science Foundation grant. Further potential collaborations are in discussion with Professor Jennifer Lewis of Harvard University and Professor Xiaoyue Ni of Duke University for a follow-up LDRD-ER proposal.