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

Abstract 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.