Method for synthesis of thin film composite membranes
The present invention relates to improved methods for the preparation of thin film composite membranes by interfacial polymerization, preferably (organic) solvent resistant thin film composite membranes. More in particular the method of the present invention allows for the preparation of thin film composite membranes wherein a thin film is deposited on a porous crosslinked support. Said method comprises the one step solidification, impregnation and crosslinking of the porous support through phase inversion by immersion of the cast membrane polymer film in an (aqueous) solvent comprising a polyfunctional monomers.
1. A method for preparing a thin film composite (TFC) membrane comprising a support, which comprises a cross-linked first polymer, and a top layer comprising a film of a second polymer, wherein said method comprises:
(i) casting a solution of said first polymer onto a suitable substrate;
(ii) preparing a solidified and impregnated support by immersing said cast first polymer solution into an aqueous coagulation medium comprises first polyfunctional monomers, such that during coagulation of said first polymer, part of said first polyfunctional monomers cross-links said first polymer, while another part of said first polyfunctional monomers are comprised in an aqueous solution that impregnates the solidified first polymer; and
(iii) contacting the solidified and impregnated support of (ii) with a water-immiscible solvent comprising second polyfunctional monomers, whereby said second polyfunctional monomers interfacially polyermise with at least one of the impregnated polyfunctional monomers of (ii) to form a thin film second polymer layer.
2. The method according to claim 1 , wherein said TFC membrane comprises a cross-linked polyimide, and a top layer comprising a polyamide film, wherein said method comprises:
(i) casting a polyimide solution onto a suitable substrate;
(ii) preparing a solidified and impregnated support by immersing said casted polyimide solution into an aqueous coagulation medium to solidify the polyimide, wherein said aqueous coagulation solution comprises polyfunctional amine monomers, such that during coagulation of said polyimide, part of said polyfunctional amine monomers cross-links said polyimide, while another part of said polyfunctional amine monomers are comprised in an aqueous solution that impregnates said solidified polyimide; and
(iii) contacting said solidified and impregnated polyimide support of (ii) with a water immiscible-solvent comprising polyfunctional acyl halide monomers, whereby said acyl halide monomers and said impregnated polyfunctional amine monomers of (ii) interfacially polymerise to form a thin film polyamide layer.
3. The method according to claim 2 wherein said polyfunctional acyl halide monomers comprise an acylchloride.
4. The method according to claim 2 wherein said polyimide is present in 6-35 weight percent of the casting solution in (i).
5. The method according to claim 2 wherein said polyimide is a polymer with the following structure:
6. The method according to claim 2 wherein said polyimide is a polymer with the following structure:
7. The method according to claim 2 wherein said polyfunctional amine monomers comprise an amine having at least two functional groups in its chemical structure, said functional groups are selected from primary amines or secondary amines.
8. The method according to claim 7 wherein said amine is a primary and/or secondary di-, tri- or polyamine.
9. The method according to claim 8 wherein said amine is at least one compound selected from: 1,2-diaminoethane, 1,3-diaminopropane, diaminobutane, diaminopentane, diaminohexane, diaminoheptane, diamino-octane, diaminononane, diaminodecane, ethylene diamine, N,N′ -dimethylethylene diamine, N,N′-diethylethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylene pentaamine, pentaethylenehexamine, tris(2-aminoethyl)amine, polyethyleneimine, polyallylamine, polyvinylamine, polyether diamines based predominantly on a polyethylene oxide backbone with a molecular weight of 50 to 20,000, trimethoxysilylpropyl-substituted polyethyleneamine having a molecular weight of 200 to 200,000, polyethyleneamine having a molecular weight of 1,000 to 200,000, m-xylylendiamine, p-xylylenediamine, multifunctional aniline derivatives, phenylene diamines, methylene dianiline, and oxydianiline.
10. The method according to claim 2 wherein said polyimide casting solution of (i) comprises any or a mixture of organic solvents selected from N-methylpyrrolidone, etrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, 1,4-dioxane, gamma-butyrolactone, water, alcohols, ketones or formamide.
11. The method of claim 1 , wherein the first polymer is a polyimide and wherein the aqueous coagulation medium comprises polyfunctional amine monomers.
12. The method of claim 11 , wherein the second polyfunctional monomers for interfacial polymerization of (iii) are selected from the group consisting of acyl halides, isocyanates, sulfonyl halides, haloformyloxy-substituted acyl halids, and isocyanate-substituted acyl halides.