Porous biodegradable polyesters. II. Physical properties, morphology, and enzymatic and alkaline hydrolysis of porous poly(epsilon-caprolactone) films

Porous poly(epsilon -caprolactone) (PCL) films were prepared by water extra ction of poly(ethylene oxide) (PEO) from their solution-cast phase-separate d blend films and the dependence of their blend ratio [X-PCL = PCL/(PEO + P CL)] and molecular weight of PEO on the porosity, pore size, crystallinity, crystalline thickness, mechanical properties, morphology, and enzymatic an d alkaline hydrolysis of the porous PCL films were investigated. The film p orosity or extracted weight ratio was in good agreement with the expected v alues, irrespective of X-PCL and molecular weight of PEO. The maximum pore size was larger for the porous films prepared using PEO having a lower mole cular weight, compared with films prepared using PEO having a higher molecu lar weight at the same X-PCL. Differential scanning calorimetry of the poro us PCL films revealed that their crystallinity and crystalline thickness we re almost constant, regardless of X-PCL and molecular weight of PEO. The Yo ung's modulus and tensile strength of the porous films decreased, whereas t he elongation-at-break increased with decreasing X-PCL. The enzymatic and a lkaline hydrolysis rates of the porous films increased with a decrease in X -PCL and an increase in the molecular weight of PEO. The porous PCL films h aving Young's modulus in the range of 2-24 kg/mm(2) and enzymatic hydrolysi s rate in the range of one- to 20-fold that of the nonporous PCL film could be prepared by altering X-PCL and the molecular weight of PEO. (C) 2001 Jo hn Wiley & Sons, Inc.