MXene filled polyetherimide matrix composites with remarkable nonlinear conductive performance and low percolation threshold

Abstract Due to the necessity of percolating network, field grading composites filled by particulate fillers usually involve high filler content which can be unfavorable for mechanical properties. Adopting high-aspect-ratio fillers is a feasible strategy of achieving low percolation threshold. In this study, a 2-dimensional early transition metal carbide, Ti3C2Tx MXene and its oxidized derivatives were adopted as fillers to prepare polyetherimide (PEI) matrix composite films with nonlinear conductive characteristics. The composite films kept insulating at low electric field and their nonlinear conductive behaviors at high electric field were induced by tunneling effect. The Ti3C2Tx/PEI composite showed a remarkable nonlinear coefficient of 10.18 at a filler content of only 6 phr and the percolation threshold of this type of composite was only about 2 phr. Nonlinear conductive characteristics of the composites can be readily adjusted by varying the content and oxidation degree of the filler. Dielectric constants of the composites were also enhanced by the fillers at low filler content with the dielectric loss remaining low. This study revealed the ability of Ti3C2Tx and its oxidized derivatives to act as fillers of field grading composites, especially for the composites requiring low filler content.