▎ 摘　　要

Graphene oxide(GO) functionalized with imidazolium ionic liquid(IL) is characterized from spectroscopic and microscopic techniques. Poly(vinylidene fluoride)(PVDF)/ionic liquid functionalized graphene oxide(GO-IL) composite(PGL) films are flexible, and exhibit fibrillar network morphology. Transmission electron microscopy indicates dendritic morphology at 3%(w/w) GO-IL and the formation of piezoelectric beta-polymorph PVDF is evidenced from wide angle x-ray scattering. PGL composites exhibit a gradual increase of melting, crystallization, glass transition (T-g) and other relaxation temperatures with increasing GO-IL concentration. The maximum increases of storage modulus (73%), Young's modulus (333%) and tensile strength (628%) occur at 3% filler concentration. Halpin-Tsai equation suggests GO sheets are randomly distributed at low GO-IL concentration but they are unidirectional at higher concentration. A sharp increase of dc-conductivity of PGL composite to similar to 10(-2) S/cm occurs with a percolation threshold of 0.1% (w/w). The dielectric permittivity increases from 7.5 for PVDF to 13.5 for 3% filler with a percolation threshold at 0.1% (w/w) filler. (C) 2015 Elsevier Ltd. All rights reserved.