Enhanced dielectric performance of poly(vinylidene fluoride)-based composites filled with hexadecylphosphonic acid functionalized nanometals

Zero-dimensional nickel nanosphere (0-D NiNS), one-dimensional silver nanowire (1-D AgNW) and two-dimensional silver nanoplate (2-D AgNP) were prepared and studied as conductive nanofiller within flexible dielectric poly(vinylidene fluoride) (PVDF) matrix. Hexadecylphosphonic acid (HDPA) modifiers were functionalized onto the surface of those nanometals. X-ray photoelectron spectroscopy (XPS) verified the functionalization of organophosphonic acid surface modification agent. X-ray diffraction characterization (XRD) suggested the surface functionalization did not change the crystal structure of nanometals. The organic dielectric surface modified layer not only acted as interparticle barriers to prevent nanometals from direct connection but also produced excellent compatibility between the fillers and the polymer matrix and ensures the dispersion of fillers in the polymer matrix. Fourier transform infrared spectroscopy (FT-IR) spectra information indicated the increase of electro-active beta-phase of PVDF composites after doping of nanometals and surface functionalization of filler. Among all the PVDF composites, dielectric materials with HDPA functionalized AgNP as fillers have the best dielectric performance. The good dielectric performance could be triggered by relatively smaller size effect, parallel micro-capacitor microstructure, particular morphology and large-small nanosize co-doping way.