[0048] The polymer material used in this example is PLGA polymer prepared by ring-opening polymerization and having the molecular weight of 200,000 determined by gel permeation chromatography.
[0049] First, a lump of PLGA polymer material was pulverized in a disintegrator. Polymer particles were passed through a sieve of 60-80 meshes to obtain polymer particles in the size of between 177 and 250 micrometers. The soluble material selected in this example is sodium chloride particles which have a particle size of about 250 micrometers. The solvent used to solve the polymer material is 1,4-dioxane.
[0050] The PLGA polymer particles were mixed with sodium chloride particles at different weight percentages. The mixture of PLGA polymer particles and sodium chloride particles were poured into the apparatus shown in FIG. 1. The apparatus in the example comprises a filtration apparatus 1 and a suction apparatus 2 which is connected to the filtration apparatus 1 and provides a pressure difference. The filtration apparatus 1, one of the conventional apparatuses, comprises a filtration vessel 3 for holding the polymer particles and the soluble particles, a Teflon filter film 4, a valve 5 for controlling a filtrate flowing in the filtration vessel 3, a filtrate conduit 6 for the filtrate flow, and a filtrate vessel 7 for receiving the filtrate. A mixture 8 of the polymer material and the soluble material was placed into the filtration vessel 3.
[0051] Please refer to FIGS. 2a to 2f which show the embodiment of the process of the invention. FIG. 2a depicts the mixture 8 of the polymer material and the soluble material which is placed in the filtration vessel 3 of the filtration apparatus 1. Then the organic solvent 9, 1,4-dioxane, was poured into the mixture for solving the surface of the polymer material, shown in FIG. 2b. The suction apparatus 2 was turned on to provide a pressure difference for sucking the surplus solvent and causing the dissolved surface of the polymer particles to fuse.
[0052] As shown in FIG. 2d, a mass of distilled ionic water 10 was poured into the filtration vessel 3 and the suction apparatus 2 was turned on again. A mass of distilled water 10 passed through the materials to solidify and precipitate the dissolved polymer material and to wash out the inside sodium chloride particles.
[0053] The solidified polymer material was taken out of the filtration vessel 3, shown in FIG. 2e, and put into a beaker 12 with distilled ionic water 11. The distilled water 11 was changed every six hours at room temperature. The polymer material was stirred in the distilled water for one day to get a porous polymer material 13, shown in FIG. 2f.
[0054] The pores of the porous polymer material 13 produced in the invention is tested according to ASTM D-3576-94. The porosity test of the porous polymer material is according to Hsu et al in J. Biomed. Mater. Res. vol:35, 107-116, 1997. The microstructure of the porous materials is observed in scanning electron microscope, operated at a current of 40 mV.
[0055] FIG. 3a shows the scanning electron microscopic results of the porous polymer material 13, wherein the mixing weight ratio of PLGA particles and sodium chloride particles is 10/90. The pore size of the porous material is between 150 and 350 micrometers. The porosity distribution within the material is quite uniform, and the pores of the porous structure are interconnecting. FIG. 3b shows the microstructure of the porous material in high magnification. It is found that the porous polymer material 13 obtained in the present invention has not only the large pores but also the micro pores, i.e. less than about 5 micrometers. The different pores structures existing in the porous material are beneficial in applications of the tissue engineering.
[0056] FIG. 4 shows the porosity of the porous polymer material 13 obtained in the present invention, wherein the mixing weight ratio of the PLGA particles and sodium chloride particles is varied. The different porosity of the porous polymer materials is formed due to different mixing ratios of PLGA particles and sodium chloride particles. The porosity of all the porous polymer materials is high than 85 vol %.
[0057] The process disclosed in the present invention can massively and rapidly produce the porous polymer materials with high porosity and interconnecting pores.
[0058] The methods and features of this invention have been thoroughly described in the above example and description. It should be understood that any modifications or changes without departing from the spirits of the invention are intended to be covered in the protection scopes of the invention.
