A dynamic hard domain-induced self-healable waterborne poly(urethane/acrylic) hybrid dispersion for 3D printable biomedical scaffolds

Abstract

Polyurethane (PU) with its efficient self-healing ability and high mechanical properties is highly anticipated but an arduous challenge to achieve. In this study, to create a win–win situation, a new strategy was introduced which is based on the triple synergistic effect of a ‘dynamic hard domain’, ‘multiple hierarchical hydrogen bonding’, and ‘semi-interpenetrating network (IPN) formation’. The dynamic disulfide bond of 2-APDS and multiple hierarchical hydrogen bonding raised from urea and urethane linkages supplement the healing ability, and concurrently, the polyacrylates and rigid aromatic moiety improve the mechanical properties of the SWPUA films. Owing to the judicious molecular engineering and aforementioned tactic, a series of self-healable waterborne PU/polyacrylic (SWPUA) films were prepared by using bis(2-aminophenyl) disulfide (2-APDS) as the ‘dynamic hard domain’, monoglyceride of castor oil (MG_CO) as a chain extender, glycerol ester of citric acid (GECA) as an internal emulsifier and different acrylate monomers with other desired reactants (polyols/diamines and diisocyanate). The resulting films exhibit good mechanical robustness, high thermal stability, and biodegradability. Notably, a maximum healing efficiency of 82.53% can be achieved within 330 s under microwave exposure (800 W) and the cut films were re-processable at 60 °C under a pressure of 60–80 kg cm⁻². Most importantly, the MTT and live/dead assays of mouse fibroblast cell lines (L929) treated with the SWPUA-2 dispersion (up to 30%) confirmed its biocompatibility. Most interestingly, SWPUA-2 can be employed to prepare a SWPUA-2/methacrylate anhydride-modified gelatin (GelMA)/gelatin hybrid ink for the development of 3D printable biomedical scaffolds.