Cetyltrimethylammonium bromide decorated MXene/polyimide nanocomposites with enhanced dielectric properties, thermostability, and moisture resistance

Abstract

AbstractUnder extreme conditions, the polymer dielectric materials are expected to have good dielectric properties and heat resistance. Polyimide (PI) has high service temperature (>250°C) and low dielectric loss, but its low dielectric constant limits its further application. The addition of MXene can significantly improve the dielectric constant of PI, but the poor compatibility between MXene and weak polar matrix leads to Bénard‐Marangoni (BM) instability in the process of thermal imidization. This issue can be solved by the surface modification of MXene. Therefore, in this work, a new cetyltrimethylammonium bromide (CTAB) decorated MXene/PI nanocomposite film was prepared by in‐situ polymerization. With the addition of 7 wt% MXene@CTAB, the PI nanocomposite shows improved dielectric constant (k = 7.8 at 100 Hz), which is 2.4 times that of pure PI due to the formation of micro‐capacitors structure and Maxwell‐Wagner‐Sillars (MWS) interfacial polarization. Its dielectric loss keeps at an ultra‐low level (0.027 at 100 Hz) while that of 7 wt% MXene/PI nanocomposite is 3.027. It is owing that CTAB inhibits the agglomeration of MXene. In addition, MXene@CTAB/PI composites have excellent thermal stability, good hydrophobicity, and low water absorption. The above properties ensure MXene@CTAB/PI composites wide application in various extreme situations.