Photografting of conducting polymer onto polymeric substrate as non-migratory antioxidant packaging
A non-migratory antioxidant clean label was developed by photografting monomers onto a conventional packaging polymer. The polypropylene (PP) film was initially brushed with glycidyl methacrylate (GMA) to prepare a reactive surface with a large amount of oxirane ring (PP-g-GMA) using a photografting method. Next, a conducting polymer (p-anisidine (PA)) was immobilized on the surface of reactive film (PP-g-GMA) through a ring-opening reaction to develop an antioxidant film (PP-g-GMA-g-PA). The chemical structure and atomic composition of the surface of the antioxidant film were characterized through FTIR and XPS, respectively. In addition, the microstructure and morphology of the grafted surface were observed by SEM and AFM. A DPPH assay and electrochemical analysis showed that the PP-g-GMA-g-PA film displayed antioxidant properties and oxidation/reduction features. Moreover, the storage test in various food matrices demonstrated that the antioxidant films can prolong the shelf life of food, in which the antioxidant film significantly retarded vitamin C degradation and oil oxidation during storage. This system exhibited non-migratory characteristics; no migration residues were detected in simulant solvents after incubation, which can be used for biomedical and packaging applications.