Fabrication of high-performance thermally conductive and electrically insulating polymer composites with siloxane/multi-walled carbon nanotube core-shell hybrids at low filler content

Abstract

A battery of siloxane (SiO)/multi-walled carbon nanotube (MWCT) core-shell hybrids are successfully fabricated by encapsulating MWCTs with siloxanes via the hydrolysis-condensation reaction. First, MWCT is treated by the surfactant to improve the surface polarity. Then, the hydrolysis-condensation reaction of tetraethoxysilane (TEOS) and different saline coupling agents is performed on the surface of MWCTs to achieve various core-shell hybrids. These hybrids serve as fillers of epoxy resin (EPR) to prepare high-performance thermally conductive, electrically insulating and strength-enhanced composites at low fillers loadings. The SiO/MWCT/EPR composite possesses high thermal conductivity (0.55 W m−1 K−1, which is 196.7% higher than pure EPR) and excellent electrical insulation (>1012 Ω) at 1 wt% filler loading. The thermal conductivity improvement mechanism for these composites containing SiO/MWCT core-shell hybrids is demonstrated in detail. Moreover, the siloxane encapsulation route for MWCTs significantly declines their electrical conductivity, which greatly upgrades the practical value of as-prepared thermal conductivity composites.