Self-Repairing Oxetane-Substituted Chitosan Polyurethane Networks

TLDR

Polyurethanes are high‑performance polymers yet remain vulnerable to mechanical damage. The study develops ultraviolet‑activated self‑repairing polyurethane networks. The networks incorporate oxetane‑substituted chitosan that, upon damage, opens oxetane rings to generate reactive ends, and UV‑induced chitosan scission crosslinks these ends to restore the network. The materials self‑repair within an hour and are suitable for coatings in transportation, packaging, fashion, and biomedical fields.

Abstract

Polyurethanes have many properties that qualify them as high-performance polymeric materials, but they still suffer from mechanical damage. We report the development of polyurethane networks that exhibit self-repairing characteristics upon exposure to ultraviolet light. The network consists of an oxetane-substituted chitosan precursor incorporated into a two-component polyurethane. Upon mechanical damage of the network, four-member oxetane rings open to create two reactive ends. When exposed to ultraviolet light, chitosan chain scission occurs, which forms crosslinks with the reactive oxetane ends, thus repairing the network. These materials are capable of repairing themselves in less than an hour and can be used in many coatings applications, ranging from transportation to packaging or fashion and biomedical industries.