Dielectric Property Tuning via Electric Field Alignment in Mxene (Ti₃C₂)-Based Polymer Nanocomposites

Orientation control is crucial for fine-tuning the functional properties of two-dimensional (2D) nanomaterials. MXene (Ti 3 C 2 ) alignment has drawn significant attention lately as the targeted properties can be controlled by manipulating the structural anisotropy. However, controlled MXene nanosheet orientation inside the polymer matrix is a complex and less understood mechanism. In this study, we applied an in-plane electric field to align the MXene nanosheets vertically inside the semicrystalline polyvinylidene fluoride (PVDF) (Tg⁓ -35°C) matrix in situ , where the amorphous phase assisted the electric field alignment at room temperature. These vertical orientations of the nanosheets were confirmed directly using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Our study reveals a significant correlation between MXene-orientation and dielectric property enhancement. PVDF- 5 wt.% MXene demonstrated the highest dielectric permittivity increase of ⁓500% because of the maximum surface polarization of the nano-capacitors inside the matrix. Interestingly, the loss value shows a sharp jump after the 5 wt. % MXene concentration, demonstrating a percolative network formation. Notably, our nanocomposite exhibited a low loss before (0.07) and after (0.66) applying the electric field, even at a high MXene concentration (20wt.%). Finally, to understand the effect of polymer domain structure on the electric field-induced orientation effect, we conducted a comparative study between non-ferroelectric poly vinyl alcohol (PVA) and ferroelectric (PVDF) polymer-based MXene nanocomposites. Interestingly, we observed a synergistic effect of the polymer chain and MXene orientation on the permittivity enhancement in the ferroelectric polymer-based nanocomposites at both high and low frequencies. This study provides fundamental insights for designing hybrid solid-state dielectric films for next-generation flexible electronics.