Production of nanochitins via a shell biorefinery process for self-assembly applications as photonic films and Pickering emulsions

Abstract

The concept of sustainable development is driving shell biorefineries to develop a cost-effective and environmentally benign approach to transform chitin into high-value products. This study describes a green, simple, and flexible shell biorefinery process for producing two kinds of nanochitins (NCh), chitin solid residues (ChSRs) and chitin nanocrystals (ChNCs), by using p-toluenesulfonic acid-assisted hydrothermal treatment. The ChSR is a bundled nanocrystal with a long length ranging from 100 nm to 450 nm and a width ranging from 10 nm to 30 nm. It has an excellent interfacial behavior between the water and oil phases due to its amphiphilic nature; thus, a foodstuff-related emulsion has been successfully fabricated from soybean oil and a ChSR suspension without the addition of any synthetic surfactants. The further hydrolysed ChNC with a length and width range of 25–225 nm and 15–30 nm, respectively, and a high zeta potential of 41 mV exists as an individual nanocrystal. Owing to the abundance of positively charged groups distributed on its surface, ChNC enables self-assembly to a highly ordered hierarchical structure. Hence, ChNCs show promising results in fabricating large-area photonic films, e.g. for application in bright and vivid automobile painting. Altogether, we provide a novel approach to produce NCh materials from crustacean shell waste and bridge the gap from process engineering to high-value product development.