Significant enhancement of dielectric properties of graphene oxide filled polyvinyl alcohol nanocomposites: Effect of ionic liquid and temperature

Fabrication of polymer nanocomposites with excellent dielectric properties in an environmentally friendly approach is a challenging job. Nanocomposites based on polyvinyl alcohol (PVA) and graphene oxide (GO) are fabricated using deionized water by solvent casting technique. The agglomerations, intercalation, and exfoliation pattern of dispersion of GO phase in the interface are observed in HRTEM and FESEM photomicrographs.1-Allyl-3-methyl imidazolium chloride (AMIC) as ionic liquid (IL) is incorporated for better dispersion and compatibility. The Fourier-transform infrared (FTIR) and Raman analysis confirms the establishment of hydrogen bonding and cation-pi interaction between AMIC and GO platelets. The enhancement of the tensile results up to 2 wt% of GO loading ensures the reinforcing nature of GO. Further increase in tensile strength in IL contend systems ensure the bridging activity, which facilitates the stress transfer at the interface. The effect of GO loading, IL, and temperature on the dielectric properties, such as dielectric permittivity (epsilon '), AC conductivity (sigma(ac)), impedance (Z ' andZ ''), and Nyquist plot are explored. The significant enhancement in epsilon ' with the incorporation of GO loading level and IL in an external electric field is mostly due to the increase in polarizable dipoles and migration of electric charge carriers, which result the accumulation of charge particles with different relaxation time at the interface. The interfacial polarization phenomena become more frequent at higher temperature, which again results increase in epsilon '. A remarkable increase in sigma(ac)and reduction ofZ ' andZ '' of the fabricated PVA/GO systems with an increase in GO loading level ensures the pronounced tunneling and hopping phenomenon at the interface. The diminished area obtained under the Nyquist plots with increase in GO loading level and temperature ensures about the decrease in bulk resistivity (R-B) and increase in charge storing ability of the developed systems. The significant improvement in dielectric properties at higher temperature reveals the negative temperature coefficient behavior of resistance (NTC) of the developed systems.