Patent ID: 7918349

Claim:
A method of preparing a composite membrane comprising a porous support and a crosslinked polyimide discriminating layer having an external surface to which are attached branched poly(alkylene oxide) polymers; the method comprising the step of coating the external surface of the discriminating layer with branched poly(alkylene oxide) polymers, wherein a branched poly(alkylene oxide) polymer comprises a backbone with poly(alkylene oxide) side chains, and where the polymer is derived from poly(alkylene oxide) macromonomers represented by formula (I): RO—[(CHR′) n —O] m —V (I) wherein R is hydrogen or a C 1-20 aliphatic or aromatic group, V is any group including a polymerizable site, each R′ is independently hydrogen or a C 1-3 alkyl group, n is an integer of 1 to 6, and m is an integer of 1 to about 200 and wherein the branched poly(alkylene oxide) polymers comprise copolymers of the poly(alkylene oxide) macromonomers of formula (I) and at least one of: glycidyl methacrylate (GMA), 2-isopropenyl-2-oxazoline (IPO) and maleic anhydride (MAH).