Investigation on tunable ferroelectricity of polymer-based composites via changing the surface state of ferroelectric nanosheets

Polymer-based materials play a crucial role in progressive electronic devices and electric power systems due to their excellent ferroelectric and dielectric performances. High ferroelectricity of the polymers could be achieved even at a low electric field with ferroelectric nanofillers introduced. However, the origin of the extra ferroelectricity enhancements of these composites besides the intrinsic ferroelectricity of fillers are still ambiguous. Herein, the Ca2Nb3O10 (CNO) nanosheets were selected as ferroelectric nanofillers, which were embedded into the polyvinylidene fluoride (PVDF)-based polymer matrix. Numerous characterization results manifested that the surface of ferroelectric nanofillers could induce the formation of polar-oriented amorphous fractions (OAFs) in the composites. Experimental results indicated these formed OAFs are the origination of the enhanced ferroelectricity of the composites. In contrast, the aluminum oxide layer was constructed onto the CNO surface to cut off the interaction between the CNO nanosheets and the polymer matrix. These effects could be eliminated when the direct contact between the nanofiller and polymer matrix is interrupted, which facilitates the energy storage performance enhancements of the composites. This work reveals the origin of the extra ferroelectricity enhancements of polymer-based composites containing ferroelectric nanofillers. It may blaze new trails in realizing multifunctional applications of polymer-based composites via surface engineering.