Transparent maltitol- cellulose nanocrystal film for high performance barrier

Abstract

The broad applications of cellulose nanocrystal (CNC) films are restricted by their low resistance against water and brittleness. In this study, high barrier transparent films composed of CNCs and maltitol, used as a bio-plasticizer (at up to 30% weight), were prepared by spray deposition. Addition of plasticizer increased the optical transmittance of the films. It also improved elongation at break and flexibility of the films, while reducing Young’s modulus and tensile strength. The barrier properties of CNC films plasticized with maltitol were significantly improved over CNC. In particular, films containing 30 wt.% maltitol showed a water vapor permeability of 3.67 × 10–12 (g/Pa.s.m) and oxygen permeability of 4.75 (cm3.µm/m2.day.Pa) corresponding to 94% and 78% reductions over CNC films, respectively. This remarkable barrier improvement is attributed to a combination of decreased porosity and the interaction of hydroxy groups of maltitol and CNCs. This interaction led to a reduction of the free hydroxy groups available to interact with the water molecules diffusing in the nanocomposite films, as confirmed by dynamic vapor sorption measurements. This study presents maltitol as a green plasticizer significantly improving the CNC film properties and enabling new barrier applications.