Structural, thermal, morphological and optical properties of PEO filled with biosynthesized Ag nanoparticles: New insights to band gap study

In this study new insight to band gap study was presented. The solution cast technique was employed in the present study for the preparation of polymer composites based on polyethylene oxide (PEO), while silver nanoparticles (AgNPs) were synthesized via the green chemistry method. Reduction of silver ions to metallic silver particles was achieved with environmentally friendly and free-of-cost quince leaves. Correlation was established between the outcomes of band gap investigation and XRD analysis. Preparation of PEO:Ag polymer composites involved addition of suspended AgNPs in various concentrations to PEO solution. PEO:Ag composite films were found to be associated with broad absorption peaks due to plasmonic metallic silver particles at 320–780 nm wavelength. The sample incorporating 15 mL of suspended AgNPs is more amorphous, according to the outcomes of XRD analysis. Meanwhile, the FTIR analysis provided categorical evidence for complexation occurring between AgNPs and PEO matrix. The shifting of FTIR bands of PEO:Ag composite films compared to pure PEO is an evidence for interaction among the composite components. The sample melting point was estimated via a thermal investigation. The outcomes of FTIR and XRD analyses were supported by the morphological study. Pure PEO was found to be associated with interconnected spherulites. At 15 mL of AgNPs, there was a decrease in spherulite size, while at 30 mL AgNPs, larger-sized spherulites appeared. Estimation of the optical band gaps of the films required an in-depth investigation of their optical properties. The outcomes of absorption edge study and band gap analysis emphasized that optical dielectric loss is a skilled method for band gap study. Based on theoretical background and experimental approaches, deep insights into band gap behaviour and materials structure are documented.