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- The demand for multifunctional nanocomposites with superior electrical, dielectric, and antimicrobial properties has driven the development of polymer-graphene hybrid materials. This study investigates polyvinylpyrrolidone (PVP)-graphene nanocomposites with varying graphene concentrations (1–20 wt%) synthesized via the solution casting method, focusing on their electrical, dielectric, and antimicrobial properties. Structural and morphological characterizations confirm successful graphene incorporation and dispersion within the polymer matrix. Impedance spectroscopy reveals significant enhancements in electrical and dielectric properties, with a percolation threshold observed at 10 wt% graphene loading. The optimized composition, i.e., PVP-10 wt% graphene nanocomposite, demonstrates a significant enhancement in AC electrical conductivity (~ 3.70 × 10− 6 S/m at 1kHz) compared to pure PVP (~ 3.40 × 10− 7 S/m 1 KHz) exhibiting an enhancement of >10 times, facilitated by the development of a conductive network within the PVP matrix. Dielectric analysis reveals frequency-dependent behavior for both the real and imaginary parts of the electrical modulus, with variations observed based on graphene content. Furthermore, electromagnetic interference (EMI) shielding effectiveness (SE) was about 20 dB (frequency range: 1 kHz – 8 MHz) for PVP-10 wt% graphene nanocomposite, demonstrating the potential for shielding applications. The nanocomposites also exhibit enhanced antimicrobial efficacy against E. coli and S. aureus, with inhibition zones increasing with graphene content. These findings highlight the potential of PVPgraphene nanocomposites as multifunctional materials for electronics, biomedical coatings, and EMI shielding. The study provides crucial insights into the structure-property relationships, enabling the rational design of polymer-graphene composites for next-generation applications.
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- Graphene-based poly(2-ethyl-2-oxazoline) (PEOX) and polyvinylpyrrolidone (PVP) blend-matrix nanocomposites were prepared employing different weight percentages of graphene nanoplatelets as filler by ultrasonication assisted solution casting method. These nanocomposites were explored for their thermal, electrical, dielectric, and mechanical properties, and antimicrobial efficiency. Thermogravimetric analysis demonstrated that graphene operates as a barrier to limit thermal diffusion across the PEOX-PVP blend matrix, and hence, improve thermal stability of nanocomposites. The dielectric and electric properties such as dielectric constant, dielectric loss, loss tangent and electrical conductivity of PEOX-PVP-10 wt% graphene nanocomposite were found to increase with temperature. The presence of semi-circles in the Cole-Cole plot indicated the existence of a relaxation process in the conduction mechanism of the nanocomposite. AC electrical conductivity, σ , of PEOX-PVP-10 wt % graphene nanocomposite was found to obey Jonscher's power law. The temperature-dependent behavior of frequency exponent, s, of AC σ AC discusses the applicability of correlated barrier hopping (CBH) model. The extracted DC conductivity from AC conductivity studies was found to be temperature-dependent and obey Arrhenius relation with activation energy of conduction, E a , of 0.41 eV and 0.39 eV in the lower and higher temperature regions, respectively. The mechanical properties of nanocomposites were enhanced dramatically when graphene loading was increased, demonstrating that a better interaction exists between graphene and the PEOX-PVP blend matrix. PEOX-PVP-15 wt% graphene nanocomposite showed superior mechanical properties (tensile strength: 9.18 MPa and Young's modulus: 3.19 MPa) among the synthesized nanocomposites. Further, the antibacterial activities of these nanocomposites against Gram-negative (E. coli) and Gram-positive (E. facecalis) bacteria revealed differential action.
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