Enhanced dielectric properties of homogeneous Ti₃C₂T_x MXene@SiO₂/polyvinyl alcohol composite films

Exploring flexible dielectrics with high dielectric constant and low loss is pertinent for many applications in electronic devices. In the present work, a non-ferroelectric polymer, polyvinyl alcohol (PVA), was used to fabricate homogeneous dielectric composite films with a relatively high dielectric constant and a low dielectric loss by using 2D nano sheets (Ti₃C₂T_x MXene) as the filler. To limit dielectric loss, SiO₂ was coated onto the surface of MXene to provide interfacial barrier effect and suppress dielectric loss. MXene@SiO₂/PVA composite films showed lower dielectric losses at low frequencies (from 20 Hz to ~ 10 kHz) compared with MXene/PVA composite films. MXene@SiO₂/PVA composite films with 2.5 wt% MXene loading and 5 wt% (with respect to MXene content) SiO₂ coating had a dielectric constant of 27.2 (a 292.5% rise compared to neat PVA film) and a dielectric loss of only 0.057 (a 259.6% reduction compared to MXene/PVA composite film) at 100 Hz and room temperature (RT). In addition, this SiO₂-coated composite film had stable dielectric properties (dielectric constant and loss change from 27.2 to 29.3 and 0.057 to 0.104, respectively) in the temperature range of RT to 60 °C. This work provides a promising way to fabricate PVA-based dielectric composites with excellent dielectric properties for practical applications in electronics.