Effects of polycaprolactone viscosity on morphology, mechanical properties, water uptake, and cellular viability in poly(3‐hydroxybutyrate)/polycaprolactone blends for tissue engineering

Abstract In this study, two polycaprolactones (PCLs) with different molar masses were evaluated regarding their influence on the melt processability, morphology viscoelastic and mechanical properties, water uptake, and fibroblast and pre‐osteoblast viability of poly(3‐hydroxybutyrate)/polycaprolactone (PHB/PCL) blends. PHB/PCL blends were prepared in a mixing chamber following 90/10 and 70/30 ratios and later compression molded. The torque rheometry results show that the blends' processability is influenced by the ratio and molar mass of the PCL used in its obtaining, those being more strongly affected by the PCL with lower molar mass. The results indicate that the polymeric blend was immiscible in any proportion and molar mass of PCL used. The blends showed a sea‐island morphology in which the diameter of the dispersed phase depended on the composition. In general, even though the molar mass of PCL differed, the blends showed similar behaviors. However, a great difference was observed in the fracture mechanism for the blend with PCL of lower molar mass, which did not present the ability to fibrillate before rupture, due to its low mechanical resistance. The blends showed greater water uptake capabilities when compared to the pure polymers due to the diffusion of water through the gaps in between the phases. The blends showed high cell viability when tested in fibroblast cells of the L929 lineage and pre‐osteoblast cells of the MCT3‐E1 lineage, indicating that these materials are promising for application in bone tissue engineering.