Influence of fraction of porogen and polymer concentration on the surface and mechanical properties of thermoplastic polyurethane/HA/rGO composites

Porous scaffolds are critical for tissue regeneration because they provide structural support while also allowing cell adhesion, proliferation, and nutrient delivery. The systematic creation of polymeric scaffolds with variable structure-property correlations is critical to the advancement of regenerative medicine. In this study, porous thermoplastic polyurethane (TPU, 15-20 wt.%) composites reinforced with hydroxyapatite and reduced graphene oxide (HA+rGO, 2-3 wt.%) were fabricated using solvent casting/particulate leaching (SCPL) to investigate the coupled effects of polymer concentration and porogen ratio (NaCl/TPU = 4.5-5.75 v/v) on scaffold performance. A systematic matrix of formulations was studied to determine the relationships between porosity, morphology, mechanical behavior, and surface qualities. Scaffolds demonstrated significant porosity (89–94%) with pore dimensions within the biologically advantageous range of 367–456 μm, which was directly influenced by the polymer concentration and porogen ratio. Increasing the porogen ratio enhanced pore interconnectivity and surface wettability, leading to reduced contact angles and increased surface energy, which promotes protein adsorption and cell adhesion. Higher TPU concentrations, on the other hand, resulted in thicker pore walls and significantly increased compressive strength (up to 0.82 MPa), which is commensurate with the criteria for cartilage-like tissues. These findings demonstrate strong structure-property connections, revealing how porogen-rich formulations maximize interfacial bioactivity while polymer-rich formulations improve mechanical robustness.