Composite polyamide membrane with branched poly(alkylene oxide) modified surface
Composite membranes that exhibit long-term resistance to biofouling comprise a porous support and a crosslinked polyamide discriminating layer having an external surface, the discriminating layer comprising a branched poly(alkylene oxide) (PAO) polymer attached to its external surface. The branched PAO polymer typically has the structure of a molecular comb or brush, and is made by polymerization of a PAO macromonomer of the following formula: RO—[(CHR′) n —O] m —V in which R is hydrogen or a C 1-20 aliphatic or aromatic group, V is any group containing a polymerizable site, each R′ is independently hydrogen or a short chain alkyl group, n is an integer of 1-6, and m is an integer of 1 to about 200. The α end group can be either polymerized or copolymerized.
1. 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).
2. The method of claim 1 wherein the branched poly(alkylene oxide) polymers comprise copolymers of the poly(alkylene oxide) macromonomers of formula (I) and glycidyl methacrylate (GMA).
3. The method of claim 1 wherein the branched poly(alkylene oxide) polymers comprise copolymers of the poly(alkylene oxide) macromonomers of formula (I) and 2-isopropenyl-2-oxazoline (IPO).
4. The method of claim 1 wherein the branched poly(alkylene oxide) polymers comprise copolymers of the poly(alkylene oxide) macromonomers of formula (I) and maleic anhydride (MAH).
5. A method of preparing a composite membrane comprising a porous support and a crosslinked polyamide 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 V is a derivative of at least one of: p- and m-vinyl benzene, p- and m-vinyl benzoic acid, methacryloyl chloride, acryloyl chloride and isopropenyl oxazoline; R is independently hydrogen or a C 1-20 aliphatic or aromatic group, 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.
6. The method of claim 5 wherein V is a derivative of at least one of: p-vinyl benzene, m-benzene, p-vinyl benzoic acid and m-vinyl benzoic acid.
7. The method of claim 5 wherein V is a derivative of at least one of: methacryloyl chloride and acryloyl chloride.
8. The method of claim 5 wherein V is a derivative of isopropenyl oxazoline.