Combining hydrophilic MXene nanosheets and hydrophobic carbon nanotubes for mechanically resilient and electrically conductive elastomer nanocomposites

Abstract

It is challenging to process elastomers with two types of fillers having disparate morphologies and surface properties. In this study, hydrophilic Ti3C2Tx MXene nanosheets and hydrophobic carbon nanotubes (CNTs) were compounded with an elastomer latex to prepare 3-phase nanocomposites that demonstrated highly improved mechanical and functional properties. Multi-walled CNTs were modified with hexadecyltrimethylammonium bromide (CTAB) to produce an overall positive surface charge. The modification yielded not only a spontaneous electro-static interaction between MWCNTs and the negatively charged MXene nanosheets but also promoted a relatively uniform dispersion of the hybrid nanofiller in the elastomer matrix. Raman and X-ray photoelectron spectroscopy confirmed the modification of MWCNTs and the structural integrity of both nanofillers. The hybrid fillers achieved remarkable compatibility with the matrix through the reactions between Ti in Ti3C2Tx MXene and N in both the elastomer (nitrile rubber) and the modifier (CTAB). Micrographs revealed an enhanced degree of filler dispersion compared with those nanocomposites containing non-assembled fillers. Due to the bridged and interconnected structures of the hybrid fillers, the electrical conductivity of the resulting nanocomposites was markedly increased and the mechanical properties (e.g., tensile strength and tangent modulus) displayed much improved synergism. In addition, the chemical resistance was substantially increased due to the network formed between the hybrid fillers and the elastomer macromolecules.