Self-healing properties and repairing mechanism of biobased polyurethanes with ethoxylated castor oil and with oxime-urethane dynamic bonds

Non-covalent adaptive networks offer innovative solution for the self-healing polyurethanes. However, achieving a balance between quick self-healing and good mechanical performance remains a challenge. This study focuses on design and synthesis of bio-based polyurethane (PU) materials with tailored properties by manipulating the reactivity and steric accessibility the hydroxy groups of castor oil polyols (primary and secondary hydroxy groups). Using neat castor oil and its ethoxylated derivative, we developed PU materials with varying mechanical properties and self-healing ability. The ethoxylated castor oil PU materials exhibited enhanced self-healing abilities and elasticity. The IR investigation demonstrated that the formation and breaking of ordered hydrogen bonds in urethane and oxime- urethane units of soft PU matrix is the main factor responsible for elasticity and self-healing ability of polyurethanes. The self-healing process does not affect the hard domains and microphase structure remains constant, which provides reservation of mechanical performance. This work highlights the critical role of stereochemistry in designing high-performance, self-healing polymer materials with tailored properties.