Facile grafting hyperbranched poly(thiol ether-ester) onto multiwalled carbon nanotubes (MWCNTs) via thiol-yne click chemistry to enhance the thermal conductivity, mechanical, and thermal properties of MWCNTs/epoxy composites

In this study, we report an efficient and rapid technique to achieve the covalent functionalization of multiwalled carbon nanotubes (MWCNTs) by hyperbranched poly(thiol ether-ester) (HPTEE) via thiol-yne click chemistry method. The structures of the MWCNTs grafted with HPTEE (MWCNTs-HPTEE) were characterized and their effects on the epoxy-based composites were investigated. It was found that the hyperbranched polymers have been successfully grafted onto the MWCNTs surface thorough covalent bonds, which can greatly improve the dispersion of MWCNTs in epoxy matrix and the interfacial interaction between them, contributing to the largely enhanced mechanical and thermal properties. When 0.6 wt% MWCNTs-HPTEE was added, the composites exhibited the best mechanical properties. An impressive 180% increase in the impact strength and 72.3% increase in flexural strength were observed with respect to the neat epoxy resin. Moreover, at the same filler content, the thermal stability and thermal conductivity of MWCNTs-HPTEE/epoxy composites outperformed the composites containing the raw MWCNTs. Experimental results demonstrated that the resulted MWCNTs-HPTEE are more effective on the improvement of properties of epoxy-based composites as compared with raw MWCNTs.