Facile fabrication of dual-crosslinked single network heterostructural polyurethane hydrogels with superior mechanical and fluorescent performance

Mechanical properties (such as strength and toughness) of commonly synthetic polyurethane hydrogels (PUHs) cannot satisfy demands of practical load-bearing applications. Consequently, it is still a challenge to develop PUHs combined with excellent strength and toughness. Here, a new type of PUHs is synthesized through using polyethylene glycol, isophorone diisocyanate, trimethylolpropane (TMP) and polyphenol compound resveratrol (RST). Both TMP and RST as crosslinkers are linked to polyurethane main chains by a sequentially chemical crosslinking pre-polymerization, which results in the formation of a dual crosslinking network structure of PUHs, and the interconnected porous networks generated after freeze-drying PUHs are further studied by scanning electron microscope. Interestingly, the PU-RST hydrogels prepared by varying the weight ratio of RST versus TMP exhibit high mechanical properties and good load recoverability, in which the optimal tensile strength and breakage elongation of the equilibrium swollen hydrogels reach 1.87 MPa and 801%, respectively. This work offers a facile method for preparing dual-crosslinked PUHs with high mechanical strength and toughness, broadening application fields of the PUHs. [Display omitted] •A new dual-crosslinked polyurethane hydrogel was prepared by twice chemical crosslinking.•During preparation, trimethylolpropane and natural polyphenol compound resveratrol were both used as chemical crosslinkers.•The obtained polyurethane hydrogel can fluoresce and possess interconnected porous networks after lyophilized.•By adjusting the weight ratio of TMP versus RST, the dual-crosslinked PU hydrogel showed excellent mechanical performance.