Liquid crystalline polyurethane composites based on supramolecular structure with reversible bidirectional shape memory and multi-shape memory effects

In this study, a novel series of supramolecular liquid crystalline (LC) polyurethane composites, named SMPU-#HOBA (# represents the molar ratio of HOBA/BINA), were successfully prepared by incorporating hexadecyloxybenzoic acid (HOBA) into pyridine-containing polyurethane (PU). The effect of HOBA on the structure, morphology, and properties has been carefully investigated. The results demonstrate that the obtained SMPU-#HOBA composites not only maintained the LC property of the HOBA mesogen, but also enhanced the intrinsic crystallization of the soft segment phase. Thus, the composites showed an excellent multi-shape memory property with two crystalline temperatures. Moreover, self-gripping was demonstrated revealing reversible bidirectional shape memory by virtue of molecular flipping and movement of the hard segment domain. These composites display a rare combination of LC properties, multi-shape memory properties, and reversible bidirectional shape memory properties, which makes them ideal for many potential applications in smart temperature sensitive devices.