In this study, a novel polyurethane porous 3D scaffold based on polyethylene glycol (PEG) and polytetrahydrofuran glycol (PTMG) was developed by in situ polymerization and freeze drying. Aliphatic hexamethylene diisocyanate (HDI) as a nontoxic and safe agent was adopted to produce the rigid segment in polyurethane polymerization. The chemical structure, macrostructure, and morphology—as well as mechanical strength of the scaffolds—were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), and tensile tests. The results show that the HDI can react mildly with hydroxyl (–OH) groups of PEG and PTMG, while gas foaming action caused by the release of CO₂ occurred simultaneously in the reactive process, resulting in a uniform porous structure of PU scaffold. Moreover, the scaffolds were soaked in water and freeze dried to obtain higher porosity and more interconnective microstructures. The scaffolds have a porosity of over 70% and pore size from 100 to 800 μm. The mechanical properties increased with increasing PEG content, while the hydrophilicity increased as well. After immersion in simulated body fluid (SBF), the scaffolds presented a stable surface structure. The gas foaming/freezing drying process is an excellent method to prepare skin tissue engineering scaffold from PTMG/PEG materials with high porosity and good inter connectivity.

Due to the complexity of surgery for large-area bone injuries, implanting a large volume of materials into the injury site remains a big challenge in orthopedics. To solve this difficulty, in this study, a series of biomimetic hydroxyapatite/shape-memory composite scaffolds were designed and synthesized with programmable pore structures, based on poly(ε-caprolactone) (PCL), polytetrahydrofuran (PTMG) and the osteoconductive hydroxyapatite (HA). The obtained scaffolds presented various pore structures, high connectivity, tunable mechanical properties, and excellent shape memory performance. Moreover, the mineralization activity of the developed scaffolds could enhance the formation of hydroxyapatite and they showed good biocompatibility in vitro. The in vivo experiments show that scaffolds could promote the formation of new bone in critical size cranial defects. The programmable porous scaffold biomaterials exhibited potential application promise in bone regeneration.

A novel shape memory polymer composite scaffold was developed with programmable pore structures, and the introduction of citrate into calcium phosphate could improve the formation of a new bone.