The carbon dioxide molecule becomes cluster to minimize the free energy; as a result pore nucleation is created. These pores cause the significant expansion of polymeric volume and decrease in polymeric density. A three- dimensional porous structure (scaffolds) is formed after completion of foaming process. The porosity of the scaffolds is controlled by the use of porogens like sugar, salts and wax (Ikada, 2006). The polymer (eg, PLGA) that expands in foaming process fused together around the porogen to create a continuous polymeric matrix, and also entrap any other molecule which is present in the mixture. The mix polymer and.
