Highly Cross-Linked and Stable Shape-Memory Polyurethanes Containing a Planar Ring Chain Extender

Shape-memory biomaterials, especially those stable against degradation, are attractive for applications in the biomedical fields, such as artificial bone scaffold material, artificial blood vessel material, and so on. In this study, shape-memory polyurethanes (SMPUs) were synthesized based on poly(ε-caprolactone) (PCL) diol, dicyclohexylmethylmethane-4,4′-diisocyanate (HMDI), and planar ring chain extenders. Catechol (PCTE), 1,4,9,10-anthracenetetrol (ANTE), and 2,3,6,7,10,11-hexahydroxytriphenylene hydrate (HHTP) with different rigidities were used as the stationary phase to produce the SMPUs. Shape-memory and degradation properties of the SMPUs were characterized. It was found that poly(PCL & PCTE urethane) (PCPU), poly(PCL & ANTE urethane) (PCAU), and poly(PCL & HHTP urethane) (PCHU) showed outstanding shape-memory properties with the shape fixity rate of 90.9%, 90.4%, and 94.0% and shape recovery rate of 99.1%, 99.1%, and 98.7%, respectively, following the triple-shape-memory testing procedure. Moreover, during the 6 month hydrolysis process, all SMPUs had 90.6%–94.3% of weight remaining, demonstrating good hydrolysis resistance with highly stable thermomechanical performance. These SMPUs possess excellent shape-memory properties and are highly promising for applications as implant materials in vivo.