US Patent 10369725 Method for preparing free-standing polymer film with micropores

The present invention relates to a method for preparing a free-standing polymer film with micropores in a simple and economical way, and particularly to a method for preparing a free-standing polymer film with micropores that includes: (a) forming a thin film of a water-soluble polymer on a substrate; (b) forming a thin film of a hydrophobic polymer on the water-soluble polymer thin film; (c) treating the substrate having the polymer thin films formed on with a mixed solution of a solvent and a C1-C3 alcohol and drying the substrate; and (d) immersing the dried substrate in water to dissolve the water-soluble polymer thin film and thereby to peel the hydrophobic polymer thin film from the substrate.