Tunable optical and structural properties of PEO/SA polymer nanocomposites via nanocurcumin incorporation: Experimental and theoretical perspectives

Abstract

This study investigates the structural, optical, and antibacterial properties of polyethylene oxide/sodium alginate (PEO/SA) blends incorporating nanocurcumin (50–120 nm) via a solution casting technique. The novelty lies in the synergistic combination of experimental and theoretical approaches to understand how nanocurcumin concentration affects the material's properties. XRD analysis revealed that increasing the nanocurcumin content (up to 10 wt%) resulted in a 27 % reduction in crystallinity, while FTIR confirmed physical dispersion without any chemical interaction. UV-Vis spectroscopy revealed a characteristic nanocurcumin peak at 360 nm and showed tunable band gaps, with direct band gaps increasing from 5.2 to 5.6 eV. SEM demonstrated a homogeneous nanocurcumin dispersion at lower concentrations (4 wt%) but agglomeration at higher concentrations (10 wt%), resulting in a ∼40 % reduction in surface roughness. Antibacterial tests showed pure nanocurcumin exhibited strong activity against both Gram-positive (21 mm inhibition zone for S. aureus ) and Gram-negative (20 mm for E. coli) bacteria. However, the PEO/SA-nanocurcumin composites showed no inhibition due to PEO's capping effect. DFT simulations identified the most stable interaction mode and validated the role of nanocurcumin in modulating electronic properties.