Abstract: Disclosed are reverse osmosis anisotropic gel-type membranes having the structure: ##STR1## WHEREIN N IS A WHOLE NUMBER; A is a divalent group derived from piperazine and having the structure: ##STR2## WHEREIN X IS 0 TO 8 AND R is an alkyl group, and Q is at least two divalent organic groups selected from the group consisting of: ##STR3## wherein Y is O or S, ##STR4## Also disclosed are processes for preparing such membranes.

Abstract: Polymeric piperazinamides suitable for use in reverse osmosis membranes. These polymeric piperazineamides consist essentially of the repeating unit ##STR1## wherein x is zero or a whole number from 1 to 8, R is a substituent such as alkyl, and --A-- is a bivalent radical, namely an organic dicarbonyl radical which either is always of the formula ##STR2## wherein X is oxygen or sulfur, and R' and R" are each hydrogen, alkyl, or aryl, or else where some of said radicals --A-- are of formula (III) and the remainder of said radicals --A-- are organic dicarbonyl radicals differing from said formula (III).