Green Fabrication of High-Performance Chitin Nanowhiskers/PVA Composite Films with a “Brick-and-Mortar” Structure

Chitin is a biobased and renewable biopolymer which consistents with the green and sustainable development. However, the strong inter- and intra-molecular hydrogen bonding interactions of chitin endow it with very poor solubility and processability, which extremely limit its broad application. In this work, a simple “building block reorganization” strategy has been developed to prepare chitin-based composite film with a “brick-and-mortar” structure. After successively experiencing salt-induced “preaggregation” and alkali-induced “hydrogen bonds remolding”, the mixture of chitin nanowhiskers (ChNWs) and poly(vinyl alcohol) (PVA) was processed into high strength and transparent composite film with ChNWs as “bricks” and PVA as “mortar”. The hydrogen-bond remolding process had successfully promoted the interactions between ChNWs and PVA, and optimized the microscopic “brick-and-mortar” structure, therefore resulting in much improved mechanical properties, water resistance, and barrier properties of the composite films. Moreover, the whole process for preparing the composite films was carried out in aqueous medium at room temperature, which makes it a promising candidate for green processing of natural polysaccharide.