Bio-inspired modification of TiO<inf>2</inf> nanowires for fabrication of High-κ polymer nanocomposites

Abstract

High-dielectric-constant (High-κ) nanocomposites are demonstrated to show great promise as energy storage materials. The introduction of high-κ nanomaterials into ferroelectric polymers has proven to be a promising strategy for the fabrication of high-κ nanocomposites. One dimensional large-aspect-ratio nanowires exhibit superiority in enhancing κ and energy density of polymer nanocomposites in comparison to their spherical counterparts. However, the large electrical mismatch and incompatibility between the nanofillers and polymer matrix usually give rise to seriously distorted electric field, resulting in poor dielectric properties and weak energy storage capability of the polymer nanocomposites. Therefore, the rational functionalization of nanofillers to optimize the performance of the polymer nanocomposites are vital. Herein, inspired by adhesive proteins in mussels, dopamine is employed to functionalize the TiO 2 nanowires. Dopamine functionalization facilitates the excellent dispersion of these nanowires in the ferroelectric polymer matrix because of the strong polymer/nanowire interfacial adhesion. Moreover, at a relatively low electric field of 200 MV m−1, 10 vol % dopa@TiO 2 /poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] nanocomposites exhibit discharged energy storage densities of 2.96 J cm−3, more than one and a half of the pristine polymer (1.84 J cm−3), also much higher than commercial biaxial-oriented polypropylene (BOPP, 0.40 J cm−3). The results and methods presented here provide deep insights into the design and fabrication of polymer nanocomposites for dielectric and energy storage applications.