Sustainable leather alternatives: High-performance and dyeable bio-based materials from fungal chitin and tannic acid

Leather alternatives (LAs) offer a promising solution to address the environmental and ethical concerns associated with traditional leather production relying animal hides and chemical tanning agents. However, synthetic polymer-based LAs, such as polyurethane and polyvinyl chloride, have limited broader applications due to their complex manufacture process, high emission of volatile organic compounds, and poor biodegradability. Herein, we present the development of biomass-based LAs fabricated by combining two low-cost natural components - fungal chitin and plant polyphenols (i.e., tannic acid, TA), through non-covalent interactions. Specifically, chitin was extracted from common mushrooms (e.g., Pleurotus ostreatus and Agaricus bisporus) through alkali treatment, and the biodegradable LAs were subsequently prepared by filtration, TA crosslinking, hot pressing, and dyeing. The incorporation of TA significantly enhanced the mechanical and antibacterial properties of LAs, achieving a tensile strength of 156 MPa. Additionally, the chitin-based LAs exhibited good water vapor permeability and were dyed in various colors with excellent levelness and fastness. Importantly, this synthetic strategy avoided the use of organic solvents and hazardous chemicals, showing potential for large-scale production. This work provides a simple and effective strategy to prepare biodegradable LAs from low-cost non-animal resources, aligning with social ethical standards and environmental requirements for sustainable development.