Interfacial Self-Assembly of Graphene Networks at 1 vol% Enables Piezoresistive and Electrothermal Silicone Foams

Segregated network composites achieve electrical percolation at minimal filler loadings by localizing conductivity to architectural boundaries. However, achieving this architecture typically requires tedious multi-step processing, often incompatible with scalable manufacturing. Here, we report the single-step synthesis of a silicone composite segregated network composed of self-assembled percolating graphene networks. These networks are templated by graphene-stabilized water-in-oil emulsions, created by spontaneous exfoliation of graphite at oil/water interfaces generated by agitation. After polymerization of the silicone and removal of the dispersed aqueous phase, the resulting foams achieve conductivities of 0.43 S/m at a 1.37 vol% loading of graphene. This is a 12-fold reduction compared to prior interfacial assembly methods, which require 16.5 vol% loading and thousands of hours of processing to achieve comparable electrical conductivity. Architectural segregation decouples mechanical and electrical properties, enabling application-specific modulus tuning. The foams exhibit reversible piezoresistance with a U-shaped strain response, are stable through 5000 cycles, and provide voltage-controlled heating to 143 °C at milliamp current densities, three orders of magnitude lower than those of continuous CVD graphene networks. The low thermal mass of the air-filled foam structure provides rapid thermal response, achieving 28-second de-icing from -17 °C.