Multilayers assembly of bio-polyelectrolytes onto surface modified polypropylene films: Characterization, chelating and antioxidant activity.

In order to remove the trace transition metal ions which catalyze the oxidation in food, chitosan (CS) and sodium alginate (ALG) multilayers were assembled on the polypropylene (PP) surface grafted with polyacrylic acid (PAA) to obtain PP-g-PAA/(CS/ALG)n films. The morphology of the active films was observed, and the thickness of each single assembled layer was about 7 nm. The chelation ability of the films improved with increasing number of (CS/ALG)n multilayers, and Cu2+ chelating quantity of PP-g-PAA/(CS/ALG)15.5 films was about 3.4 umol/cm2 for 72 h at pH about 5, improved by about 9.92 % as compared with PP-g-PAA films. In addition, the PP-g-PAA/(CS/ALG)n films had chelation activity for both Cu2+ and Fe2+, suggesting the potentiality in antioxidant food package application.