Poly(carbonate‐urea‐urethane) networks exhibiting high‐strain shape‐memory effect

Abstract

A challenge in the design of shape-memory polymers (SMPs) is to achieve high deformability with a simultaneous high shape recovery ratio. Here we explored, whether SMPs featuring large deformation capability and high shape recovery ratios can be created as polymer networks providing two kinds of netpoints based on covalent bonds and physical interactions. As a model system, we selected poly(carbonate-urea-urethane)s (PCUUs) synthesized by a precursor route, based on oligo(alkylene carbonate) diols, isophorone diisocyanate (IPDI), and water vapor. The PCUU networks exhibited a one-way shape-memory effect (1W-SME) with programmed strains up to εprog = 1000% whereby they provided excellent shape fixity (92–97%) and shape recovery (≥99%) ratios. The switching temperatures (Tsw) varied between 36 and 65 °C and increased with the increasing molecular weight of the oligo(alkylene carbonate) diol and length of the hydrocarbon chain between the carbonate linkages. Tsw was also influenced by the strain applied during programming (εprog). Poly(carbonate-urethane)s have been reported to have good biocompatibility and biostability, which in the combination of high-strain capacity and high Young's modulus makes the obtained PCUUs interesting candidate materials suitable for medical devices such as medical sutures or vascular stents.