{HEAD ~ Asymmetric polyimide membranes} are prepared from {TAIL ~ tetracarboxylic acid dianhydrides} and diamines 
are prepared from
{ HEAD ~ Asymmetric polyimide membranes } are prepared from { TAIL ~ tetracarboxylic acid dianhydrides } and diamines
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH