A pore modified microporous membrane is disclosed which is made by the process of incorporating a polymerizable vinyl monomer within the pores of a microporous membrane followed by polymerization to secure the resulting polymer within the pores. The process is particularly suitable for modifying a hydrophobic microporous membrane with a hydrophilic polymer, as occurs for example when polyacrylic acid is secured into the pores of a polypropylene microporous membrane. In further applications of the present invention, the inventive method may be used to produce liquid membrane supports for use with or without active carriers.