Non-covalent interaction cooperatively induced stretchy, tough and stimuli-responsive polyurethane-urea supramolecular (PUUS) hydrogels

Up to now, fabrication of strong and stimuli-responsive supramolecular hydrogels via an easy molecular design and synthesis procedure is still a big challenge. In this work, a series of hydrophobically modified linear polyurethane-urea copolymers and one polyurethane copolymer were prepared via a greatly simplified one-pot approach to investigate the synergistic effect between hydrogen-bonding and hydrophobic effects. FT-IR and various mechanical performance studies show that not only a longer hydrophobic spacer (C-12) but also a stronger hydrogen-bonding unit (urea) is necessary for their synergistic effect to yield high water containing, transparent, stretchy and tough supramolecular hydrogels. Moreover, these supramolecular materials also show nice cyclic shape-memory behaviours which can be realized under mild conditions, e.g. in air and water at room temperature. The noncovalent interaction's synergistic effect and stimuli-responsive character are expected to dramatically expand the design and choice of tough and smart supramolecular hydrogels/materials for biomaterials.