Isolation of thermostable cellulose II nanocrystals and their molecular bridging for electroresponsive and pH-sensitive bio-nanocomposite

Abstract

Sustainable, economical, and green extraction of cellulose Ⅱ nanocrystals from lignocellulose under mild conditions is still challenging since the highly recalcitrant nature of lignocellulose. Herein, a sustainable system using ammonium persulfate (APS)-catalyzed deep eutectic solvent (ADES) was developed to produce functional cellulose Ⅱ nanocrystals (CNCs) with a high yield of 82.3 %. The obtained CNCs had excellent thermal stability (>350 ℃), high crystallinity of 76.6 % with surface carboxyl groups, and superior dispersion stability. CNCs played a role of both molecular bridging and nano-sized effect in gelatin matrix, which combined with gelatin tightly through multiple hydrogen bonds to prepare bio-nanocomposite films with outstanding electric-responsiveness and pH-sensitivity. It was proved that CNCs had remarkable reinforcing potential and effective stress transfer capacity, contributing to a 187 % enhancement in tensile strength and an approximately 110 % increase in Young’s modulus of the formed CNCs/gelatin nanocomposite films when 0.5 wt % CNCs was loaded. Therefore, the study may open the door for developing a green and sustainable avenue to produce functional CNCs, and is of great significance for the building of CNCs-based functional nanocomposites.