Synthesis and Characterization of the Novel Injectable Hydrogels Based on Waterborne Polyurethane

ABSTRACT Bone tissue engineering requires injectable scaffolds that can fill irregular bone defects, provide mechanical support, and deliver bioactive molecules. In this study, injectable hydrogels based on waterborne polyurethane (WPU) were synthesized using polycaprolactone (PCL) and polyethylene glycol (PEG) as soft segments, with gelatin incorporated as a natural biopolymer. Cross‐linking was achieved via Schiff‐base bonding between gelatin and glyoxal. To enhance mechanical properties and enable controlled drug release, Folic acid‐loaded layered double hydroxide (LDH‐FA) nanoparticles were incorporated at weight percent concentrations of 3%, 5%, and 7%. The resulting hydrogels exhibited good compressive strength, reaching up to 2.59 kPa, which falls within or above the range reported for conventional injectable hydrogels used as bone scaffolds (1–5 kPa). They also demonstrated good biocompatibility and sustained release of Folic acid. Characterization techniques, including NMR, FT‐IR, GPC, DLS, and rheological tests, confirmed the desirable properties of the hydrogels. These findings highlight the novelty of integrating LDH‐FA nanoparticles into WPU/gelatin hydrogels and demonstrate their potential as biocompatible and mechanically suitable injectable scaffolds for future application in bone defect repair.