DTAB-functionalized MXene nanofillers for enhancing dielectric and mechanical properties of TPU-based composites

Abstract

With the rapid advancement of flexible electronics technology, there is substantial demand for flexible dielectric materials that exhibit both high dielectric constant and low dielectric loss. In this work, thermoplastic polyurethane (TPU)-based composites were developed by incorporating decyltrimethylammonium bromide-functionalized MXene (MXene@DTAB) as the filler, with the aim of enhancing the dielectric properties of TPU materials. The embedment of the alkyl long chains, derived from DTAB, significantly improved the dispersion of MXene in organic solvents and promoted a more uniform distribution of MXene within the TPU matrix, as evidenced by EDS mapping. Consequently, the MXene@DTAB/TPU composite with an 8 wt% filler content achieved a maximum dielectric constant of 161.91 at 1 kHz, which was nearly 14 times higher than that of pure TPU (11.02), while maintaining a low dielectric loss of 0.61. In addition, the results of dynamic mechanical analysis indicated an increase in rigidity and energy dissipation, highlighting the improved mechanical properties of the composites. Furthermore, based on the MXene@DTAB/TPU dielectric material, a flexible capacitive pressure sensor was created and it exhibited an enhanced sensitivity of 0.137 kPa⁻¹ (<24 kPa). Overall, the dielectric materials developed in this study demonstrate promising potential for applications in energy storage, electromagnetic interference shielding, flexible sensors, and dielectric elastomer actuators.