Membrane post treatment
View Patent ↗The invention relates to polymeric ultrafiltration or microfiltration membranes of, for instance, Halar, PVDF or PP, incorporating PVME or vinyl methyl ether monomers. The PVME may be present as a coating on the membrane or dispersed throughout the membrane or both. The membranes are preferably hydrophilic with a highly asymmetric structure with a reduced pore size and/or absence of macrovoids as a result of the addition of PVME. The PVME maybe cross-linked. The invention also relates to methods of hydrophilising membranes and/or preparing hydrophilic membranes via thermal or diffusion induced phase separation processed.
1. A method of making a hydrophilic membrane prepared from a polymeric material, comprising preparing a dope comprising the polymeric material and a compatible at least partially water soluble polymeric hydrophilising agent comprising vinyl methyl ether monomers to produce a hydrophilic membrane comprising the polymeric material and poly(vinyl methyl ether).
2. A method according to claim 1 wherein the at least partially water soluble polymeric hydrophilising agent is soluble in an amount of at least 5-10 g/l at standard temperature and pressure.
3. The method according to claim 1 , further comprising crosslinking the poly(vinyl methyl ether).
4. The method according to claim 3 , wherein crosslinking the poly(vinyl methyl ether) comprises exposing the hydrophilic membrane to irradiation.
5. The method according to claim 1 , wherein the dope comprises between 0.1 weight % and 2.5 weight %.