Synergistic carbon nano-fillers enabled PDMS composites with enhanced mechanical-electrical properties for reliable electrothermal applications under extreme conditions

Flexible electrothermal materials with good processability, excellent electrothermal performance and reliable environmental stability are highly desired for many emerging applications. Inspired by the interlaced structure of fish nets, we designed and fabricated polydimethylsiloxane (PDMS) composites containing well-interconnected conductive carbon fillers, i.e., a branched structure superconductive carbon black (SCB) and rod-shaped vapor grown carbon fiber (VGCF). By optimizing the carbon fillers, a fishnet-like conductive network was constructed in PDMS matrix. Notably, such hybrid carbon fillers not only optimize rheological behavior during processing but also greatly improve the PDMS’s electrical and mechanical properties. Typically, the optimized 12 SCB/12 VGCF-P composite film with appropriate processing performance has low electrical resistivity (0.72 Ω·cm), high tensile strength (3.5 MPa) and high elongation at break (247%). Such a composite shows excellent electrothermal performance, and its steady-state temperature can reach 101.1 °C within 15 minutes under a safe voltage of 25 V. It also has robust mechanical stability (stable electrothermal performance after 1000 bending/twisting cycles, slight loss at 20% tensile strain) and environmental tolerance (stable after 1 year outdoor exposure, 1 month acid/alkaline soaking and post-puncture testing). Clearly, this work provides a simple strategy to fabricate flexible composites with excellent electrothermal performance and environmental reliability, showing promise as advanced de-icing materials for large-scale applications.