Grafted Polyurethane Copolymers with Notable Changes in Tensile and Shape Memory Properties upon Addition of Acid and Base

Ionic cross-linking of polyurethane (PU) was performed using grafted glutaric acid (GA) or dimethylamino propanol (DAP) to enhance the mechanical properties and control the degree of interaction using acid or base. The effect of ionic cross-linking on the water compatibility, thermal phase transition of soft segments, tensile mechanical strength, and shape memory properties were determined by comparison with ordinary PU. The water compatibility of PU could be improved by grafted acidic or basic functional groups. The breaking tensile stress and shape recovery capability increased significantly relative to ordinary PU due to ionic cross-linking but notably decreased upon the addition of acid or base due to the disruption of ionic cross-linking. It was demonstrated that the water compatibility and mechanical properties of PU could be controlled using ionic cross-linking and the disruption of ionic cross-linking by adding acid or base.