Spin-coated polyvinylidene fluoride/graphene nanocomposite thin films with improved β-phase content and electrical conductivity

Abstract

In this study, the major aim was to enhance the β-phase content and thus the electrical conductivity of polyvinylidene fluoride (PVDF) films via addition of graphene nanoplatelets (GNPs) using the spin-coating technique. To this end, various concentrations of GNPs were added to the PVDF solution and the nanocomposite films were then characterized with scanning electron microscopy (SEM), optical microscopy (OM), atomic force microscopy (AFM), and water contact angle (WCA) measurement. SEM results revealed that GNPs improved the uniformity and integrity of surface structure at low to medium concentrations (1 and 3 wt%) but higher inclusions (5 and 7 wt%) made the films less uniform due to the formation of large agglomerations as detected by OM. AFM showed that the nanocomposite loaded with 3 wt% of GNPs exhibited the highest roughness profile which was in agreement with WCA results based on which the same formulation led to the highest hydrophobicity (~ 134°). In contrast with the structural analysis, the four-point probe and conductive AFM results revealed that the higher the GNPs content, the higher the electrical conductivity. Such enhanced conductivity was attributed to the increased amount of β-phase crystals in PVDF as a result of spin-coating process and GNP incorporation.