Crosslinking as an efficient tool for decreasing moisture sensitivity of biobased nanocomposite films

Chitosan-nanoclay bio-hybrid films were successfully crosslinked with glutaraldehyde, genipin and glyoxal. Moisture sensitivity of films decreased as a result of crosslinking which led to improved barrier properties against water vapor and oxygen. Films containing chitosan (6.6 g/m2) with genipin (3.3 g/m2) and nanoclay (6.6 g/m2) had water vapor transmission rate of 72 g × 100 µm/(m2 × 24 h) which was 34% lower as compared to pure chitosan and 30% lower as compared to chitosan/nanoclay without crosslinkers. Glyoxal induced crosslinking resulted in 92% reduction in oxygen transmission rate at 80% relative humidity as compared to pure chitosan films. Oxygen transmission through glyoxal (3.3 g/m2) treated chitosan/nanoclay film was 2.8 cm3 × 100 µm/( m2 × 24 h) which was 53% lower as compared to chi-tosan/nanoclay without crosslinkers. In addition, nanoclay and especially glyoxal crosslinking prevented the water va-por sorption of chitosan considerably. Crosslinking may be used as an efficient tool for enhancing the exploitability of naturally hydrophilic biopolymers towards new high-value applications, such as food packaging.