A stretchable and elastic supramolecular hydrogel with water-responsive shape-memory behavior, which can be realized under mild and green conditions, was developed.

to now, fabrication of strong and stimuli-responsive supramolecular hydrogels via easy molecular design and synthesis procedure is still a big challenge. In this work, a series of hydrophobicly 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 effect. FT-IR and various mechanical performance studies show that not only longer hydrophobic spacer (C12) but also stronger hydrogen-bonding unit (urea) are 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.

Hydrogels with obvious strain hardening and high resilience properties in both stretching and compressing processes are constructed by simple free-radical copolymerization of acrylamide and reactive pseudo-polyrotaxane.

Microfluidic fabrication of helical microfibers is still a big challenge. The reason is that this always includes designing the necessary geometrical channels and chemical conditions to first form a flowing liquid jet, which has to be continually reacting and rapidly evolving in time from viscous liquid to a flexible solid to maintain the helical structure inside the microfluidic channels. In this report, dextran aqueous solution and liquid PEG400 are infused separately into the inner and outer channels of a simple single emulsion microfluidic device, respectively. The formed two phase stream then enters a widening collection tube, where automatically formation of dextran helical fiber happened due to water shifting and widening of the channel cooperatively induced buckling. Various experimental conditions that influence the amplitudes, wavelengths, and diameters of the formed helical fibers are discussed.