Carboxymethyl cellulose/polyvinyl alcohol-based antioxidant film strengthened by physical/chemical bonding of cinnamaldehyde-tannin-metal nanoparticles

Carboxymethyl cellulose (CMC) is a potentially biodegradable substrate widely used in antioxidant food packaging films. However, the rigid structure and large number of hydroxyl groups of CMC films result in poor mechanical properties and are prone to hygroscopicity, which limits their practical application. In this study, we developed a self-assembled multifunctional cinnamaldehyde-tannin-metal composite nanoparticle (CIN-TA metal nanoparticle) that coats cinnamaldehyde via catechol bonds between metal ions and tannic acid to form nanocomposites that produce physical and chemical crosslinks with the CMC matrix. This modification significantly improved the mechanical properties of the CMC-based composite film (tensile strength of 69.78 MPa and elongation at break of 104.4 %), while improving its hydrophobicity (contact angle of 119.31°) and DPPH radical scavenging rate up to 89.4 %. This method is convenient and promising for the preparation of CMC-based food packaging films with mechanical strength, hydrophobicity and antioxidant properties.