Bifunctional metavanadate promoted chitosan/cassava biopolymer films with photo-switchable wetting properties: unveiling the surface restructuring mechanism.

Biopolymer films derived from starch and chitosan were soaked in vanadium salt solutions to produce vanadium metallopolymer films. Visible light irradiation induces significant color shifts from yellow to green due to changes in the oxidation state of vanadium. The material was observed to undergo dramatic structural changes upon incorporation of vanadium, with further restructuring occurring after visible light illumination.