Dominant nature of 7-hydroxy 4-methyl coumarin dye on thermal, fluorescence and antimicrobial properties of PVA/OMS blend films

This article focused on the fabrication of 7-hydroxy 4- methyl coumarin (7H4MC) dye doped Polyvinyl alcohol/Oxidized Maize Starch (PVA/OMS) blend films by employing user friendly solvent casting technique. The thermal stability, crystallanity, surface morphology and optical properties of the films were investigated by using Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Fluorescence (FL) and Ultraviolet-Visible (UV-Vis) Spectroscopy respectively. The TGA and DSC results illustrate that the blend films are thermally stable and miscible over the entire composition. The XRD analysis confirmed the semi crystalline nature of all the obtained films with the intense peak at 2 theta = 19. 49 degrees. The AFM topographic images had shown a smoother and homogeneous surface at the higher weight percentage of 7H4MC of blend films. The UV-Visible spectra display the absorption peaks at 325 nm for control PVA/OMS and two peaks at 329 nm, 370 nm arises after doping of 7H4MC in PS blend associated with pi-pi* electronic transition may be due to the charge transfer (CT) groups. The optical band gap is reduced on the addition of 7H4MC dye in the control blend. The fluorescence spectra revealed that the fabricated films exhibited good blue light emission under ultraviolet light and shows maximum fluorescence emission at 442 nm for 0.008 wt. % of 7H4MC. Moreover PSC blend films exhibited superior antimicrobial properties as compare to control blend film. Hence, the obtained outcomes are suggested that the PVA/OMS (PSC) blend films are appropriate materials for optical and biological application.

Automated summary

This study focused on fabricating 7H4MC dye doped PVA/OMS blend films using a user-friendly solvent casting technique, and investigated their thermal stability, surface morphology, and optical properties. The results showed that the blend films were thermally stable, had smooth surfaces, and exhibited reduced optical band gap and enhanced fluorescence emission when doped with 7H4MC. Additionally, the PSC blend films showed superior antimicrobial properties compared to control blend films, making them suitable materials for optical and biological applications.