Thin-film composite membranes synthesized by multi-step coating methods
The invention relates to methods for the synthesis of a thin-film composite membrane, comprising the following steps: a) providing an ultrafiltration porous support membrane, coated at the outer surface with a thin film, synthesized through interfacial polymerisation or interfacial initiation of polymerisation, b) contacting the membrane with a first solution comprising a first monomer, and allowing the solution to impregnate inside the thin film of the membrane, c) discarding the first solution comprising the first monomer, d) contacting the membrane with a second solution comprising a second monomer, and allowing the solution to impregnate inside the thin film of membrane, whereby the second monomer reacts with the first monomer and optionally with reactive groups of the thin film, e) discarding the second solution comprising the second monomer.
1 . A method for synthesizing a thin-film composite membrane, the method comprising a first cycle of (a), (b), (c), (d), and (e):
(a) providing an ultrafiltration porous support membrane having an outer surface coated with a thin film and synthesized through interfacial polymerization or interfacial initiation of polymerization;
(b) contacting the ultrafiltration porous support membrane with a first solution comprising a first monomer, and allowing the first solution to impregnate inside the thin film of the ultrafiltration porous support membrane;
(c) discarding the first solution;
(d) contacting the ultrafiltration porous support membrane with a second solution comprising a second monomer, and allowing the second solution to impregnate inside the thin film, whereby the second monomer reacts with the first monomer and optionally with reactive groups of the thin film; and
(e) discarding the second solution, and
repeating at least one additional cycle of (b), (c), (d), and (e),
wherein in the at least one additional cycle of (b), (c), (d), and (e), monomer order of the first monomer and the second monomer in (b) and (d) is switched.
2 . The method according to claim 1 , wherein the first monomer and/or the second monomer in the at least one additional cycles are different from the first monomer and/or the second monomer in the first cycle.
3 . The method according to claim 1 , wherein the first monomer and the second monomer in the first cycle and each of the at least one additional cycle are identical.
4 . The method according to claim 1 , further comprising repeating (b) to (e) in a consecutive cycle after the first cycle, wherein the first solution in the consecutive cycle comprises the second monomer of the first cycle and the second solution in the consecutive cycle comprises the first monomer of the first cycle.
5 . The method according to claim 1 , wherein the first monomer or the second monomer contains a functional group selected from the group consisting of an acid halide, a diamine, a triamine, a polyamine, an isocyanate, a polyol, a monocarboxylic acid, a dicarboxylic acid, and a functionalized triazine.
6 . The method according to claim 1 , wherein the first monomer or the second monomer contains a functional group selected from the group consisting of a tertiary amino, a tertiary thiol, a base, and a hydroxyl group.
7 . The method according to claim 1 , wherein:
the first monomer is a nucleophilic monomer; and
the second monomer is a polyfunctional epoxide monomer.
8 . The method according to claim 1 , wherein the second solution is a solvent or ionic liquid that is immiscible with the first solution.
9 . The method according to claim 7 , wherein the polyfunctional epoxide monomer is selected from the group consisting a phenyl glycidyl ether, bisphenol-A-diglycidyl-ether, tetraphenolethane tetraglycidylether, neopentylglycol diglycidylether, trimethylolpropane triglycidylether, 1,4-butanediol diglycidylether, triglycidyl-p-aminophenol, tetraglycidyl-4,4′-diaminodiphenylmethane, and diglycidyl ester of hexahydrophthalic acid.
10 . The method according to claim 1 , wherein the porous support membrane has a thickness from 0.1 μm to 500 μm.
11 . The method according to claim 1 , further comprising repeating (b), (c), (d), and (e) until a top layer is obtained with a thickness greater than 100 μm and pores having pore sizes less than 15 nm.
12 . A method for nanofiltration or reverse osmosis of components, the method comprising filtering a solution over a thin-film composite membrane obtained by the method of claim 1 .
13 . The method according to claim 12 , wherein the components are suspended in an organic solvent, in a combination of organic solvent and water, or in a polar aprotic solvent.
14 . The method according to claim 12 , wherein the components are suspended in an aqueous solvent having a pH from 0 to 4 or from 10 to 14.
15 . The method according to claim 12 , wherein the components are suspended in an aqueous oxidizing solvent.
16 . The method according to claim 12 , wherein the components are suspended in NaOCl.