Work

Cold Extrusion of Stretchable Liquid Metal–Polymer Composite Feedstock for Intrinsically Conductive 3D Printing

Year: 2026

Type: article

Abstract: Additive manufacturing of soft conductive materials enables flexible electronics, sensors, and robotic systems, yet is often constrained by high-temperature melt processing, postprint activation, or rigid conductive inclusions that reduce compliance. Here, we introduce a cold-extrusion strategy to create feedstock for liquid metal (LM)/thermoplastic elastomer composites that overcomes these limitations, enabling additive manufacturing of intrinsically conductive soft structures. By lightly solvating the polymer matrix, the composite enters a transient, putty-like processing state that enables extrusion without elevated temperature while preserving high LM loading (>60 vol %) and uniform droplet dispersion. Crucially, we leverage the high shear forces inherent to the extrusion process to drive droplet coalescence within the putty, directly forming a feedstock with a percolated, electrically conductive network. The continuously extruded LM/thermoplastic polyurethane feedstock is then pelletized and directly fabricated into multidimensional, conductive architectures using elevated-temperature extrusion-based 3D printing, without the need for thermal sintering, mechanical embossing, or secondary conductive inclusions. The printed composites reach notable conductivities of 0.4–1.8 × 104 S/m while retaining extensibility above 200% strain, demonstrating an additive manufacturing workflow that enables simultaneous printability, conductivity, and mechanical compliance. These results establish a general strategy for additive manufacturing of conductive thermoplastic elastomer composites for scalable fabrication of soft electronic and robotic systems.

Source: ACS Applied Polymer Materials

DOI: 10.1021/acsapm.6c01792