Abstract: This invention provides a process for making microporous membranes from a polymer solution and the membranes therefrom. A thermal assist, such as heating of the polymer solution can be effected subsequent to shaping the solution, such as by forming a film, tube or hollow fiber of the solution under conditions that do not cause phase separation.. In a preferred embodiment, the formed solution is briefly heated to generate a temperature gradient through the body of the formed solution. The polymer in solution then is precipitated to form a microporous structure. The formation of a wide variety of symmetric and asymmetric structures can be obtained using this process. Higher temperatures and/or longer heating times effected during the heating step result in larger pore sizes and different pore gradients in the final membrane product.

Abstract: The present invention provides for a method of producing an integral multilayered porous membrane by simultaneously co-casting a plurality of polymer solutions onto a support to form a multilayered liquid sheet and immersing the sheet into a liquid coagulation bath to effect phase separation and form a porous membrane. The support can be a temporary support or form an integrated support for the membrane. The plurality of layers may be of the same polymer or different, same concentration or viscosity or different and may be subjected to the same processing conditions or different ones to form unique structures.