The laterally attached tartaric acid of polyurethane copolymer and its impact on shape memory and low-temperature flexibility

The tartaric acid was laterally attached to polyurethane through the carbamate of polyurethane, and the impact on the shape-memory and tensile properties of polyurethane was investigated. The electrostatic repulsion of the tartarate could reduce the molecular interactions between polyurethanes, a result that was designed to improve low-temperature flexibility while maintaining high and reproducible tensile strength and shape recovery above room temperature. The attachment of the tartaric acid was quantitatively determined by acid–base titration, and the change in the molecular interaction between hard segments was confirmed via infrared spectroscopy. Both cross-linking density and viscosity experienced an unusual increase with increasing tartarate content due to partial cross-linking caused by the grafting reagent. Shape recovery and retention were reproducible over repeated shape-memory tests. Finally, the low-temperature flexibility was determined at −10°C, and the reason for the difference was discussed.