Effect of Disulfide Bond Density on the Properties of Polyurethane/Epoxy Interpenetrating Networks

Interpenetrating polymer networks (IPNs) are widely used as damping materials across various industries. However, they are susceptible to issues such as microcracking or fracture over long-term service periods. To address these challenges and improve the long-term performance of IPNs, this research focused on designing and synthesizing self-healing polyurethane (PU)/epoxy (EP) interpenetrating networks (PU/EP-IPNs) enhanced with dynamic disulfide bonds. The incorporation of these bonds significantly enhanced the damping and self-healing properties of the materials. The shape memory performance was evaluated, demonstrating high shape fixation rates of up to 95.0% and exceptional shape recovery rates of up to 99.7%. These results indicate the materials' ability to revert to their original shape upon heating above the glass transition temperature (T_g). In addition, the effective damping temperature range of the material reached 61.4 °C, and the loss factor was 0.859. This indicates that the enhancement of damping performance is closely related to the increase in disulfide bond density. The formation of the IPN between PU and EP also contributed to improved mechanical and thermomechanical properties. These PU/EP-IPNs exhibit significant potential as innovative damping materials with self-healing capabilities.