Fabrication, characterization of poly(MA-co-NIPA)-graphene composites and optimization the dielectric properties using the response surface method (RSM)

Poly(Maleic anhydride-N-isopropyl acrylamide poly(MA-co-NIPA) copolymer was synthesized by Free radical polymerization method. Response surface methodology (RSM) was used for optimizing the dielectric constant (έ) and dielectric loss factor (ε՛՛). The aim of this study is to determine the quantitative relationship between selected parameters (frequency, applied voltage and graphene content) at room temperature. The importance of process parameters in the model is assessed by analysis of variance (ANOVA) investigation. Our results show that, with increasing the frequency the έ and ε՛՛ of the polymers decreases, whereas voltage has no significant effect on έ and ε՛՛ of the composites. With the incorporation of graphene into poly(MA-co-NIPA) the έ and ε՛՛ considerably increased by 244% and 387% respectively. The model predicted the maximum value of the έ (13) when the frequency was set at 4506, the voltage was set at 1.45, and the graphene content was set at 14.97 wt%. Also, the RSM indicated that maximum ε՛՛ (1969) was achieved at the frequency of 512, at the voltage of 20.44, and at the graphene content of 14.76 wt%. The morphology of composites was investigated by scanning electron microscopy (SEM). SEM results demonstrated that the poly(MA-co-NIPA)-graphene composites has interconnected and they form different morphologies with the increase of GNs content. ATR tests showed that no significant change in chemical bond and crystallization is found in composites.