Abstract
Abstract Carbon nanotubes (CNTs) are known to have remarkable mechanical strengths with Young’s modulus in the order of ~1000 GPa. Therefore, it is generally expected that CNTs can be used as additives for reinforcements of composite materials. However, many studies have shown that addition of CNTs did not result in high-performance composite materials, which is attributed to the inhomogeneous dispersion and poor interactions with the matrix. Therefore, how to avoid CNTs aggregation and to improve the CNT-matrix adhesions are two key issues determining their reinforcement effects. In this study, surfactants were used to help dispersion of CNTs in solutions. Surfactants and CNTs form comicelle structures, which were then used as templates to synthesize SiO2/CNT and Cu/CNT micro rods. Experimental results show that CNTs are almost parallel to each other in these micro rods. In the presence of SiO2/CNTs and Cu/CNTs micro rods, where the content of CNTs is about 5 wt%, the Vicker’s hardness of SiO2 glass and YBaCuO ceramic are enhanced by ~45 % and ~20 %, respectively. The surfactant-CNT comicelles system was also used in emulsion polymerization to synthesize PMMA-grafted CNTs. The grafted PMMA polymer chains can help dispersion of CNTs in composite polymer matrix, and the surface grafted polymer chains can significantly improve the poor interactions between CNTs and the matrix. Both TEM and SEM data unambiguously show that loads can be completely transferred to CNTs, which leads to breakage of CNTs. The CNT breakage processes can be well described by a “breakage-sliding-fusion” model. The storage modulus of PMMA polymer can be enhanced by ~170 GPa upon addition of 15 wt% PMMA-grafted CNTs.