Study on Mass Transfer during the Formation of PLLA 3-D Scaffolds by ScCO2 Induced Phase Separation

The two-way mass transfer behavior between solvent and non-solvent is a key factor effecting on the pore size and size distribution of 3-D scaffolds formed by ScCO2 induced phase separation process. The mathematical model of the mass transfer related to this process is presented on the basis of the model developed by Reuvers. By means of the composition paths calculated by this model in the ternary phase diagram, the pore size and size distribution of PLLA 3-D scaffolds are analyzed under different conditions (solution concentrations, CO2 pressures and temperatures).The calculated results are verified by experiment. The results show that the pore size of the PLLA 3-D scaffolds increases with the decrease of solution concentration and increase of the CO2 pressure and temperature.