Organosolv lignin as natural grafting additive to improve the water resistance of films using cellulose nanocrystals

Abstract

Within the framework of research on the valorization of by-products from 2nd generation biorefineries, we designed novel nanocomposite materials composed of lignin and cellulose nanocrystals. These nano-composites were in the form of thin films which could be self-supported or supported on glass or quartz slides. These materials were prepared by coating or casting the polymer mixtures at ambient conditions. The lignins used included synthetic lignin oligomers as standards and organosolv lignin fractions from maize stalks and spruce wood. The Fenton’s reagent was incorporated into the polymeric mixture to improve the dispersion of lignin and to facilitate its grafting onto the surface of cellulose nanocrystals. This grafting process improved the anti-UV property, water resistance, water retention of the thickener films and micromechanical properties of cellulose/lignin films. On the nanocomposite market, the combination of these physico-chemical properties with known antibacterial property of lignin on one hand and oxygen barrier property of cellulose nanocrystal films on the other hand, would make relevant the use of these films in food and non-food (medical, packaging, surface coverings) application fields.