Vanillin Oxime-Enabled Castor-Oil-Based Waterborne Polyurethane with Tunable Mechanical, Self-Healing, and Fluorescent Properties

It is highly desirable yet challenging to develop sustainable bio-based polyurethane with excellent mechanical properties, self-healing, and reprocessing abilities. In this study, a rigid bio-based diol (VO) containing oxime group is synthesized via the condensation reaction of lignin-derived vanillin and hydroxylamine. Subsequently, VO is introduced into a castor oil-based WPU (CWPU) system to prepare CWPU-VOs with high biobased content. The presence of dynamic oxime-carbamate bonds endowed CWPU-VOs with excellent self-healing (self-healing efficiency>95%, at 80 °C for 1 h,) and reprocessing properties. By adjusting the ratio of VO and castor oil, the mechanical properties of CWPU-VOs (tensile strength of 11.0–24.3 MPa, elongation at break of 642.2–312.0%) can be effectively tuned. In addition, due to the photolysis behavior of oxime-urethane moieties, CWPU-VOs show outstanding fluorescence anti-counterfeiting potential. This work provides a new idea for the development of high-performance waterborne polyurethane with adjustable mechanical properties, self-healing ability, and fluorescent properties.