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

Abstract

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-π 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 (ε 0), AC conductivity (σ ac), impedance (Z 0 and Z 00), and Nyquist plot are explored. The significant enhancement in ε 0 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 ε 0. A remarkable increase in σ ac and reduction of Z 0 and Z 00 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.

Flexible dielectric ZnO‐doped reduced graphene oxide bionanocomposites from solution blending for potential application in bio‐related devices

“…Recently, the dielectric properties were investigated for PVA and PVA/GO systems. GO was incorporated at 1.0 to 3.0 mass% contents 41 . For PVA/GO composites, in which the formation of hydrogen bond interactions between their components may be presumed, ε ' values were reported to vary from 526 to 1014 41 …”

“…This difference between ε ″ behaviors for mats and films was expected. The higher number of polarization processes in the films would lead to a higher number of loss mechanisms 41 …”

“…41 For PVA/GO composites, in which the formation of hydrogen bond interactions between their components may be presumed, ε' values were reported to vary from 526 to 1014. 41 In Figure 6(b), the variation of ε 00 values with frequency was plotted for the different materials at various rGO-ZnO loadings. As may be observed, ε 00 values differed remarkably within the 10 1 Hz to around 10 3 Hz frequency range.…”

“…The higher number of polarization processes in the films would lead to a higher number of loss mechanisms. 41 The dielectric loss (tan δ), calculated for each material as tan δ = ε 00 /ε', provides a measure to evaluate how much power is lost in a material versus how much is stored. 9 At 10 3 Hz, tan δ varied from 0.23 (M1) to 0.17 (M4) for the mats.…”

Polymer‐based nanocomposites fabricated by microemulsion method

“…For the construction of environmentally friendly systems to fabricate nanomaterials, ionic liquids as green solvents are regarded as the ideal replacement for traditional organic solvents. [ 100–102 ] As mentioned earlier, ILs have not only excellent solvent for both organic and inorganic compounds but also the features of nonflammability, low volatility, ecofriendly, high chemical and thermal stability and recyclability. [ 103 ] IL‐based ME systems possess all advantages of conventional MEs and then can be developed as promising media for synthesizing numerous nanomaterials.…”