Strategic synthesis and characterization of starch-based interpenetrating polymer networks for enhanced thermal stability and photophysical properties

We report the synthesis of starch-based interpenetrating polymer networks (IPNs) via grafting starch with 2-methylidenebutanedioic acid (MBDA) and prop-2-enamide (PEA), with in situ incorporation of 2-(acrylamidomethyl) malonic acid (AMA). Five polymers (P1-P5) were prepared by varying MBDA:PEA ratios and characterized by GPC, FTIR, NMR, TGA, DSC, XRD, SEM, UV-vis, fluorescence, and DLS. Among them, P4 (MBDA:PEA = 1:5) exhibited the highest thermal stability and distinct emission behavior. Enhanced properties were attributed to strong hydrogen bonding, dipolar interactions, and supramolecular ordering introduced by starch grafting and amidic functionalities. P4 displayed broad UV absorption (270-300 nm) and excitation-dependent emissions (420-440 nm), supported by conformational rigidification and clustering-induced effects. These findings demonstrate that strategic starch grafting can yield thermally stable, photophysically active biopolymers with potential in membranes, tissue engineering, and dye/metal ion removal.