Control of pore size in L-lactide/ε-caprolactone copolymer foams for tissue regeneration by the freeze-drying method

In the regeneration and repair of missing tissues, synthetic polymer scaffolds need many pores to involve cells and to supply cells with nutrients. The control of the pore size of biodegradable L-lactide/ε-caprolactone copolymer foams was studied by changing the polymer concentration and the cooling temperature in the freeze-drying method. The mixtures of polymer and 1, 4-dioxane solution were poured into an 18-8 stainless steel Petri dish and frozen. The pore size of a polymer foam tends to increase from the bottom towards the top of a Petri dish. The pore size decreased to one-half with increasing polymer concentration (1 to 10 wt%). The mean pore size in foams of 8% polymer concentration decreased from 100 μm to 20 μm as cooling temperature was lowered. This suggests that the higher cooling rate due to lower cooling temperature can produce smaller ice-crystals and result in smaller pores.