Multi-scale-filler reinforcement strategy enabled stretchable silicone elastomer with synergistically enhanced thermal conductivity and mechanical strength

As soft electronic devices and robotics advance towards high power density and miniaturization, integrating superior thermal and mechanical properties has become a big challenge for functional elastomers. Herein, a multi-scale-filler reinforcement strategy was reported for constructing stretchable, mechanically strengthened and thermally conductive silicone elastomers. The multi-scaled Al₂O₃/vinyl and methyl co-modified fumed SiO₂ (VM-SiO₂) co-filled liquid silicone rubber composite exhibited a high thermal conductivity of 1.25 W m⁻¹ K⁻¹ at ∼55 vol% filler loading, 555.7% higher than that of the matrix. The finite element simulation demonstrated that the “bridging” effect of small-scaled fillers between gaps of large-scaled spheres in the matrix lowered the interfacial thermal resistance. Meanwhile, stemming from the strong interfacial interactions between the VM-SiO₂ and matrix, up to 12.4 times higher elongation at break (7.17%) and 317.7% increase of tensile strength (3.00 MPa) were reached. We further demonstrated the potential application of the multi-scaled Al₂O₃/VM-SiO₂ co-filled LSR composites for thermal management materials.