Multi-functionalization of Al2O3 nanoparticles for enhancing thermal conductivity of epoxy natural rubber composites

The poor interfacial compatibility between inorganic thermally conductive nanoparticles and organic polymeric matrix largely limits the improvement of thermal conductivity (lambda) of composites. In this study, poly(catecholpolyamine) (PCPA) and bis-(gamma-triethoxysilylpropyl)-tetrasulfide (Si69) were used to multi-functionalize alumina (Al2O3) nanoparticles (denoted as Al2O3-PCPA-Si69) to improve the interfacial compatibility and prepare effective thermally conductive epoxy natural rubber (ENR) composites. The non-covalent PCPA modification protected the inner thermal characteristics of Al2O3 nanoparticles and the Si69 with vulcanization accelerator structure provided strong covalent bond between Al2O3 filler and rubber chains during vulcanization. Owing to the constructed thermally conductive pathways and decreased interfacial resistance, the lambda of ENR composite reached 0.3773 W (mK)-1 at Al2O3-PCPA-Si69 nanoparticles content of 30 vol%, which is 270 % of the pure ENR (0.1400 W (mK)-1). The multi-functionalization of Al2O3 nanoparticles is highly efficient and cost effective, which can be expanded in other thermally conductive fillers to make them attractive candidate for insulating electronic field.