Dual network structures of PDMS-based composite foam via anchoring liquid metal nanoparticles for improved thermal conductivity and electromagnetic interference shielding performances†

Despite their promising application prospects in electromagnetic interference (EMI) shielding, a significant challenge remains in endowing flexible porous polymer-based conductive composites with exceptional thermal management capabilities. In this study, PDMS/GNPs foam serves as a three-dimensional (3D) porous skeleton, with LM nanoparticles anchored on its surface, creating a poly(dimethylsiloxane)/graphene nanoplatelets@liquid metal (PDMS/GNPs@LM) composite foam with a dual network structure, achieved through a simplified salt template and extrusion impregnation method. Owing to the successful construction of this dual 3D network structure, when the filler loading is 22.34 vol%, PDMS/GNPs@LM foam exhibits an excellent thermal conductivity of 0.74 W m⁻¹ K⁻¹, representing a 1133% enhancement compared to the neat PDMS foam. Finite element simulations demonstrate that the LM layer network exhibits excellent heat transmission due to the effective adhesion of adjacent LM nanoparticles via the polyvinyl alcohol adhesives, with heat flux mainly transferred through the continuous LM framework. The PDMS/GNPs@LM foam possesses an outstanding electrical conductivity of 35.15 S m⁻¹ and excellent EMI shielding effectiveness of 40.8 dB (with a thickness of only 2.13 mm). Furthermore, the PDMS/GNPs@LM foams demonstrate good mechanical flexibility and exhibit rapid electrothermal response and hydrophobicity. Based on these merits, the PDMS/GNPs@LM foam is anticipated to find applications in electronics, particularly in intelligent electromagnetic protection and thermal management systems.