CAREER: Manufacturing Soft Functional Composites through Mechanically Induced Assembly of Liquid Microstructures in Elastic Films

This Faculty Early Career Development (CAREER) grant supports research to understand the fundamental processing-structure-property relationships that govern continuous manufacturing and microstructural assembly of liquid metal-based composites for a new class of soft, deformable, and robust functional materials. Soft functional composites consisting of liquid metal droplets dispersed in elastic solids have shown promising capabilities for self-healing and stretchable electronics, soft robots, and thermal-interface materials for portable devices. However, these composites are often created in a single batch which limits scalability, and the processing dependence and underlying mechanisms of how liquid metal inclusions deform and assemble during manufacturing is not well known. This research will determine the fundamental inclusion deformation mechanisms and quantify how liquid metal microstructures in soft composites evolve during processing. This research has the potential to guide the realization of new continuous manufacturing strategies for precise and highly controlled mechanical, electrical, and thermal properties in functional soft materials by tuning liquid metal inclusion morphology during processing. The knowledge gained through this research will enable future innovations in electronics and robotics, which benefits national economy and society. Additionally, the research is paired with a broader outreach program and day camp, with an emphasis on first-generation students in Southwest Virginia. The outreach program is designed to engage, excite, and develop student interest and skills in manufacturing, soft electronics, and robotics while highlighting STEM career options. The specific goal of the research is to determine the processing dependence, underlying mechanisms, and quantitative microstructural origins of how liquid metal inclusions deform and assemble in soft solids. This is achieved through a combination of controlled processing strategies such as film embossing, tentering or stretching, and roll-to-roll assembly with in-situ electrical characterization and synchronized micro- and nano-computed tomography. This approach provides the processing-structure-property relationships needed for the advanced manufacturing of soft composites through mechanically induced assembly of liquid microstructures in elastic films. The project aims to determine the fundamental liquid metal inclusion deformation mechanisms and ensuing microstructures as a function of inclusion size, shape, and volume loading. Soft functional composites with programmable properties will be created through reconfigurable microstructures by controlling droplet inclusion shape and connectivity during processing. This project will provide insights on manufacturing and assembly of liquid structures within soft elastic films, introduce new directions to control material properties through reconfigurable liquid microstructures, and enable the design and manufacturing of materials for soft electronics and robots. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.