Use of intermolecular hydrogen bonding to synthesize triple-shape memory supermolecular composites

We have developed a simple and controllable strategy to synthesize a triple-shape memory supermolecular composite (SMPU-INCh-n) through H-bonding interactions between a polymer and mesogenic units. The polymer is shape memory polyurethane (SMPU) with carboxyl groups; the mesogenic unit, named as cholesteryl isonicotinate (INCh), is a liquid crystal compound with an electron-rich pyridine ring. The H-bonding interactions between carboxyl and pyridine ring are proved by FT-IR spectroscopic analysis and 1H solid-state NMR. The introducing of INChs promotes the bonded PU segments to change into glassy form by restraining the movement of polymer chains, which is responsible for the triple-shape memory property. Therefore, the composite presents excellent triple-shape effect, and may be of great potential for applications in the biomedical field.