Stronger when wet: Water-resistant chitinous objects via zero-waste coordination with metal ions

TL;DR

This paper introduces a water-resistant, eco-friendly material inspired by arthropod cuticle, made from chitosan and nickel, which becomes stronger when wet and offers a sustainable alternative to traditional plastics.

Contribution

It presents a novel zero-waste method to produce water-resistant chitinous materials using environmentally friendly processes and metal ion coordination, mimicking biological structures.

Findings

Material's strength exceeds that of commodity plastics when wet

Method preserves original chemistry of chitosan, ensuring ecological integration

Zero waste production of large objects and consumables

Abstract

Plastics have become integral to our society due to their durability and water stability, which is achieved through strong intermolecular interactions. However, these properties also make them persistent disruptors of ecological cycles, in contrast with biological structures, which work with their environments to achieve both excellent mechanical properties and ecological integration. This study takes inspiration from the arthropod cuticle to adapt Earth's second most abundant organic molecule for use in water. The process involves the vitrification of chitosan with small traces of nickel to create a dynamic network of intermolecular bonds using environmental water, resulting in a material that increases its strength to values well above commodity plastics when wet. The approach preserves the molecule's original chemistry and therefore its seamless integration into Earth's metabolism while avoiding the use of the strong organic solvents typically associated with biomolecules. The method demonstrates the potential for a paradigm shift in manufacturing, with zero waste production of both consumables and large objects that could meet the global demand for plastic.