Castor oil-based self-healing polyurethane based on multiple hydrogen bonding and disulfide bonds

Abstract

Self-healing materials have gained significant attention due to their ability to autonomously repair damage, extending material lifespan. In this study, bio-based self-healing polyurethanes were synthesized using modified castor oil (MCO) as the soft segment and 5-(2-hydroxyethyl)- 6-methyl- 2-aminouracil (UPY) and 2,2'-diaminodiphenyldisulfide (DTDA) as dynamic components. The synergistic effect of quadruple hydrogen bonding and disulfide bonds was investigated by varying the n(UPY)/n(DTDA) ratio. Structural and mechanical properties were characterized using IR, DSC, TGA, XRD, and tensile testing. The results revealed that the castor oil-based polyurethanes exhibited transparency and amorphous structures, making them promising bio-based self-healing materials. When the DTDA content was 9.54% and the UPY content was 1.62%, the material achieved a self-healing efficiency of 96.38% under 80 °C for 12 h. Additionally, at a DTDA content of 6.65% and a UPY content of 2.43%, the tensile strength reached 17.76 MPa. Mechanistic analysis revealed that disulfide bonds played a dominant role in self-healing, while hydrogen bonds provided additional reinforcement. This work presents a novel bio-based polyurethane system with tunable mechanical and self-healing properties, contributing to the development of sustainable smart materials.