Porous polyimide films obtained by using lithium chloride as pore‐forming agent

Porous polymer films have been obtained from polyimide based on benzophenonetetracarboxylic dianhydride and 4,4'‐diamino‐3,3'‐dimethyl‐diphenylmethane by incorporating lithium chloride (LiCl) in the poly(amidic acid) precursor and subsequently leaching out the maximum possible LiCl by water Soxhlet extraction for 6 h. The resulting porous polyimide films were characterized with regard to their pore size, thermal stability and dielectric properties. The morphology of the porous polyimide films showed a uniform distribution and various pore sizes depending on the initial quantity of added pore‐forming agent. © 2013 Society of Chemical Industry