Improving thermal conductivity while retaining high electrical resistivity of epoxy composites by incorporating silica-coated multi-walled carbon nanotubes

Silica-coated multi-walled carbon nanotubes (MWCNT@SiO2) were synthesized by a sol–gel method and then incorporated into an epoxy matrix. The less stiff silica intermediate shell on the MWCNTs not only alleviates the modulus mismatch between the stiff MWCNTs and the soft epoxy, but also improves the interaction between them. The thermal conductivities of the epoxy/MWCNT@SiO2 composites increase by 51% and 67% at low filler loadings of 0.5 wt.% and 1 wt.%, respectively. At the same time, the silica shell retains the high electrical resistivity of these composites.

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► Silica shell alleviates the modulus mismatch between CNTs and polymer.
► Modulus matching improves the thermal conductivity of the composites.
► Silica shell provides the composite with electrical insulation.