Biodegradable layered double hydroxide based polymeric films for sustainable food packaging applications

In this study, solution casting was used to create hybrid biodegradable films that were made of Polycaprolactone (PCL) and Zn-Al layered double hydroxide (LDH) intercalated with salicylate (SA) (P-L-S nanocomposites). P-L-S (5%) nanocomposite film has a water vapor transmission rate of just 212.5 g/m²/day at 85% relative humidity, which is 55.5% less than that of pure PCL film. This outstanding performance of the water vapor barrier is mostly due to the convoluted action of 2D LDH nanohybrids. In addition, the hydroxyl groups of LDH create hydrogen bonds with the entering water molecules, further preventing the passage of water vapor. The aforementioned nanocomposite showed excellent biodegradability by decomposing by over 75% in just 90 days. More than 94% inhibition of E. coli and S. aureus in 30 min, which is a promising finding when compared to the existing literature, was demonstrated as a result of a controlled release of salicylate (intercalated between the inorganic lamella) to the medium. The P-L-S (5%) nanocomposite additionally showed the best radical scavenging ability against DPPH. (82%) in only 72 h. The aforementioned characteristics point to the possible uses for P-L-S nanocomposite films in the domain of biodegradable packaging.