Fabrication of multifunctional cellulose nanocrystals/poly(lactic acid) nanocomposites with silver nanoparticles by spraying method

• Ternary PLA/CNF/Ag nanocomposite films were prepared by novel spraying method.
• Both Ag nanoparticles and CNFs showed efficient reinforcing effect on the properties of PLA.
• The reduced water vapor permeability and lower migration level were detected for nanocomposites.
• The nanocomposite films show great potentials in food packaging applications.

The poly (lactic acid) (PLA)/functionalized cellulose nanocrystals formates (CNFs) were prepared by solution casting and then the binary films were sprayed with silver ammonia aqueous solution to fabricate PLA/CNF/Ag ternary nanocomposites. It was found that both deposited silver (Ag) nanoparticles and CNFs showed efficient reinforcing effect on the thermal, mechanical, barrier properties and antibacterial activity of PLA matrix. Especially, the maximum decomposition temperature (Tmax) and Young's modulus of PLA/CNF/Ag(6) nanocomposite film increased by 15.5 °C and 48.7%, respectively. Meanwhile an obvious reduction in the water vapor permeability was detected. Furthermore, the migration levels of the ternary nanocomposite films were well below the permitted limits in both non-polar and polar food simulants (60 mg kg−1), and they showed a significant antibacterial activity influenced by the Ag contents. This study reveals that the novel nanocomposite films will offer a good perspective for food packaging applications.