Liquefied chitin-derived super tough, sustainable, and anti-bacterial polyurethane elastomers

Considerable amounts of waste chitin are produced every year from the fishing industry; however, the efficient utilization of natural chitin remains a challenge. To expand the applications of natural chitin, we herein report the thermal liquefaction of chitin to promote chain extension and synthesize a liquefied chitin-based polyurethane (LCPU) elastomer with a desirable tensile strength (∼43 MPa), superior toughness (∼417.66 MJ m−3), and an extremely high fracture energy (∼567.89 kJ m−2). In this study, liquefied chitin was used for the first time as a chain extender to replace traditional polyols and polyamino compounds in the preparation of tough PU materials. The acquired extraordinary mechanical features mainly originated from the highly efficient energy dissipation of strong hydrogen-bonding clusters and strain-induced crystal structures. The prepared LCPU materials exhibited considerable recyclability and self-healing properties owing to their dynamic hydrogen bonding. In addition, they exhibited excellent anti-bacterial properties and a good biocompatibility, thereby indicating their potential for application in biomedicine, such as in the contexts of minimally invasive surgical procedures and anti-bacterial medical instruments. We believe that this strategy will encourage researchers in academia and industry to develop strong, tough, degradable, and biosafe elastic materials from natural resources.