Polycaprolactone scaffolds or anisotropic particles: The initial solution temperature dependence in a gelatin particle-leaching method

A porogen-leaching method was applied to intend fabrication of polycaprolactone (PCL) scaffolds. Following with a routine solution infiltration, freeze-drying and porogen-leaching process, the porous scaffolds were normally prepared at an initial solution temperature of 25 °C. However, the PCL anisotropic particles with the smooth and fuzzy surfaces toward the gelatin porogen and the solution, respectively, were unexpectedly obtained when the initial solution temperature was maintained at 37 °C. The freezing temperature was a governing factor for formation of the different PCL products too, while the coarsening time and the PCL concentration within 10–20% had no substantial influence. The PCL anisotropic particles are highly crystallized than the PCL raw materials. To clarify the intrinsic mechanisms, the temperature, cloud point, crystalline ability, and particle size in the solution were quantified. It is demonstrated that the sponges are formed by the traditional liquid–liquid demixing for the 25 °C solution, whereas the anisotropic particles are obtained by the solid–liquid demixing for the 37 °C solution and under the assistance of gelatin particles as nucleation sites.