Programmable liquid metal microstructures for multifunctional soft thermal composites and methods for making same

Abstract

Soft, elastically deformable composites of multifunctional materials for electronics, robotics, and reconfigurable structures. Liquid metal (LM) droplets dispersed in elastomer matrices has unique combinations of soft mechanical response with exceptional electrical and thermal functionalities. These properties are strongly dependent on the material composition and microstructure. Control of LM microdroplet morphology to program mechanical and functional properties is by annealed-deformation shaping LM droplets in soft composites to create programmable microstructures in stress-free materials. Thermo-mechanical shaping is one example of annealed-deformation shaping. This enables LM loadings up to 70% by volume with prescribed particle aspect ratios and orientation, enabling control of microstructure throughout the bulk of the material. Through this microstructural control in soft composites, a material which simultaneously achieves a thermal conductivity as high as 13.0 W mK(>70× increase over polymer matrix) with low modulus (<1.0 MPa) and high stretchability (>750% strain) is demonstrated in stress-free conditions.