Silane modification on mesoporous silica coated carbon nanotubes for improving compatibility and dispersity in epoxy matrices

A simple synthetic method for placing a mesoporous silica coating on multi-wall carbon nanotubes (CNTs@MS) was developed to improve the surface compatibility with regard to a polar epoxy matrix. In addition, the mesoporous silica shell with silanol groups on the CNTs provides a platform to attach silane molecules (e.g. 3-glycidoxypropyltrimethoxysilane, GPTMS) that enable the CNTs@MS to be incorporated into the epoxy matrix at a content of up to 20 wt.%. The viscosities of the CNTs@MS- and GPTMS-modified-CNTs@MS–epoxy composites are much lower than that of the CNTs–epoxy, and then the voids in the GPTMS-modified-CNTs@MS–epoxy composites are most significantly reduced. The effects of the CNTs@MS and GPTMS-modified CNTs@MS on the mechanical and thermal properties of the epoxy composite are investigated. The results show that the GPTMS-modified CNTs@MS improved the filler–epoxy matrix interaction, and has better compatibility in epoxy than the CNTs@MS. As the surface compatibility and interaction strength increase in the epoxy matrix, the enhancement in storage modulus, thermal conductivity and reduction in the coefficient of thermal expansion are in the following order: GPTMS-modified CNTs@MS > CNTs@MS ≫ CNTs.