Multilayer photonic films based on interlocked chiral-nematic cellulose nanocrystals in starch/chitosan

In this study, a new approach to employ and control cellulose nanocrystal (CNC) chiral nematic structure as a biodegradable, intelligent material was investigated. Tuned CNC self-assembled films were interlocked between two layers of citric acid, cross-linked starch/chitosan (1:1) films through the solvent casting process. This method increased the mechanical properties of produced films and created a selective reflection band from UV to near-IR depending on the helical pitch of the chiral nematic CNC layer. The features of these intelligent films have potential for different applications, from UV protective packaging to biomedical uses. The water vapor permeability (WVP) of the produced films decreased considerably by adding a CNC layer into the cross-linked starch/ chitosan structure. Also, the WVP was different for the different helical pitches of the CNC layer. The starch/ chitosan (outer layer) also showed a remarkable antibacterial property against E. coli, P. fluorescens, S. Enteritidis, and S. aureus which could be useful for biomedical applications or antibacterial packaging.

Automated summary

This study investigated a new approach to utilize and control cellulose nanocrystal (CNC) chiral nematic structure as a biodegradable, intelligent material, producing films with potential applications ranging from UV protective packaging to biomedical uses. The addition of a CNC layer into the cross-linked starch/chitosan structure significantly decreased the water vapor permeability (WVP) of the produced films, with different WVP values observed for different helical pitches of the CNC layer. The outer layer of starch/chitosan also exhibited remarkable antibacterial properties against various bacteria strains, which could be beneficial for biomedical applications or antibacterial packaging.