Synthesis and Functional Evaluation of <scp>PCL</scp>‐<scp>SS</scp> Self‐Healing Polyurethanes With <scp>NIR</scp>‐Responsive Behavior

ABSTRACT Self‐healing shape memory polyurethanes (SHSMPUs) integrate shape recovery and damage restoration, offering enhanced reliability and adaptability for biological applications. In this study, PCL‐SS SHSMPUs are synthesized using polycaprolactone (PCL) as the soft segment and hexamethylene diisocyanate (HDI) and 2‐hydroxyethyl disulfide (HEDS) as the hard segment. Increasing hard segment content enhances tensile strength but reduces elongation at break, with PCL‐SS3 showing the highest tensile strength (14.9 MPa) and PCL‐SS1 achieving the greatest elongation at break (1120.7%). All polyurethanes exhibit a shape fixation rate above 90%, and PCL‐SS2 achieves the highest shape recovery rate of 74%. The self‐healing properties are studied under varying time, temperature, and hard segment content, revealing that PCL‐SS1 achieves the highest healing efficiency of 97.6% after 12 h of self‐healing at 90°C. Furthermore, multi‐walled carbon nanotubes (MWCNTs) are introduced to develop polyurethane composites with near‐infrared (NIR) light‐induced self‐healing functionality. The polyurethane composites with 5% MWCNTs achieve the highest healing efficiency of 85.5% within 1 min of NIR irradiation. However, excessive MWCNTs content reduces mechanical properties due to poor dispersion. This study offers a basis for optimizing and designing self‐healing shape memory polyurethanes for applications in biomedical devices and smart materials.