Load transfer of thiol-ended hyperbranched polymers to improve simultaneously strength and longation of CNTs/epoxy nanocomposites.

• A thiol-ene click reaction was used to functionalize CNTs by thiol-ended hyperbranched polymers. • Thiol-functionalized CNTs showed well dispersion in epoxy resins. • Functionalized CNTs could increase conductivity and mechanical strength of epoxy resins. • The flexible and ellipsoidal hyperbranched polymers could deform and transfer the load. • A reinforcing mechanism was supposed and substantiated by SEM, TEM, XPS and Raman techniques. Carbon nanotubes (CNTs) have been considered as the attractively multifunctional nanomaterials for high conductivity and high strength, but it is still a challenge to prepare CNTs with high dispersion and their nanocomposites with simultaneous high strength and longation. Here, we used thiol-ended hyperbranched polymers to functionalize CNTs and obtain thiol-functionalized CNTs with excellent dispersion and good compatibility with epoxy resins matrix. The grafted thiol-ended hyperbranched polymers can supply a bridging function between epoxy resins and the CNTs to promote their interaction. The thermal conductivity, elongation, tensile, flexural and impact strengthes of thiol-functionalized CNTs/epoxy nanocomposites could be improved simultaneously by 23.33%, 37.46%, 60.74%, 26.72% and 86.71%, respectively. A reinforcing mechanism was supposed and substantiated by combining SEM, TEM, XPS and Raman techniques. The flexible and ellipsoidal hyperbranched polymers chains grafted on CNTs deform and transfer the load to increase mechanical strength and elongation. An efficient and environmentally-friendly route is introduced to functionalize CNTs and fabricate simultaneous high strength and high elongation CNTs/epoxy nanocomposites. [ABSTRACT FROM AUTHOR]