Synthesis of completely solvent-free biomedical waterborne polyurethane with excellent mechanical property retention and satisfactory water absorption

In the physiological environment, implanted biomaterials require hydrophilicity for biocompatibility and mechanical retention for deformation resistance; however, synthesizing waterborne polyurethane (WPU) materials that exhibit both properties remain a challenge. Herein, we report a WPU material crosslinked with trifunctional polycaprolactone synthesized using the microemulsion method under completely solvent-free conditions, exhibiting high retention of mechanical properties and satisfactory water absorption rates. The hydrophobic polycaprolactone triol serves a dual role: it acts as a co-stabilizer, protecting the isocyanate (-NCO) groups inside the colloid from hydrolysis during microemulsion and enhances the material's resilience to mechanical property degradation under wet conditions. The water absorption test and the retention of mechanical properties in the wet and dry states demonstrated that both the films and scaffolds retained their excellent mechanical properties under high water absorption conditions, making the material suitable for applications in biological organisms. In addition, the hemolysis rate test, degradation solution cytotoxicity, and cell death staining preliminarily demonstrated that the material exhibited excellent biocompatibility. This synthesis process and structural design allowed WPU to exhibit mechanical retention and water absorption under wet conditions. This WPU material was synthesized using a completely solvent-free microemulsion process (MWPU) and has broad application potential in the biomedical field. Synthesis biomedical waterborne polyurethane with high strength retention and satisfactory water absorption by a solvent free method.