Integration of low-melting-point alloys and thermoplastic elastomers for 3D printing of multifunctional composites

Due to the significant differences in the physical and chemical properties of polymers and metals, their additive manufacturing is conducted using very different and incompatible methods or conditions. Such incompatibility is a significant limitation for multimaterial 3D printing and fabrication of 3D functional composites. We address this issue by creating functional composites composed of thermoplastic elastomers, Field's metal, and graphene; and their 3D printability by fused filament fabrication is achieved. The fully recyclable 3D-printable composites are featured with widely tunable internal structures and mechanical, thermal, and electrical properties. Multiphysics modeling is further developed to elucidate the structure-property relationship. The 3D structures can be transformed from insulative to conductive based on the melting and coalescence of Field's metal nanoparticles. The incorporation of graphene bridges the adjacent Field's metal particles and significantly enhances conductivity. Such 3D-printable polymer-metal hybrid platform could enable advancements in soft electronics and robotics and in energy storage.