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