Ionic complex for enhancing performance of water treatment membranes

DETAILED DESCRIPTION OF THE INVENTION The ionic complex which constitutes a discriminating layer of the membranes of this invention results from electrostatic attraction between the cationic groups of the first compound and the anionic groups of the second compound.
The cationic groups of the first compound are preferably quaternary ammonium, pyridinium or imidazolinium groups.
The anionic groups of the second compound are preferably carboxylate, sulfonate or phosphonate moieties.
Optionally, in some embodiments of the invention, the first and second compounds, after deposition on the support, can be crosslinked via reaction of reactive groups these compounds bear or by use of a crosslinking agent.
Illustrative of reactive groups are epoxide, vinyl, ##STR1## Normally, the quaternary ammonium, imidazolinium or pyridinium group does not react with carboxylate, phosphonate or sulfonate groups to form covalent bonds via nucleophilic displacement under the conditions of membrane formation and use.
Both compounds bearing quaternary ammonium, imidazolinium and/or pyridinium groups and those bearing carboxylate, phosphonate and/or sulfonate groups, which are operable in the subject process, are well known in the art.
These compounds can include: (1) hydrophobic groups, (2) polymerizable moieties or (3) polymers.
The hydrophobic groups can be hydrocarbyl (i.
e.
, a monovalent hydrocarbon) or substituted hydrocarbyl, such as perfluoroalkyl or dialkyl siloxane moieties.
Exemplary hydrophobic groups are described in the surfactant literature.
The hydrophobic group can bear other substituents provided these substituents do not deleteriously affect membrane characteristics.
Illustrative hydrophobes include C.
sub.
8 to C.
sub.
20 mono- or divalent hydrocarbon radicals, C.
sub.
4 to C.
sub.
20 perfluorinated hydrocarbon radicals or poly(dimethyl siloxane) moieties.
Prepolymer compounds are compounds bearing at least one group capable of reactions in situ to form polymers which are not deleterious to desired membrane characteristics