Membrane comprising cross-linked polyfunctional epoxy compound

A microporous membrane comprises a microporous support and a hydrophilic coating on the microporous support, the coating being made by applying to the microporous support a quantity of a polyfunctional epoxy compound comprising at least two epoxy groups, and then cross-linking the polyfunctional epoxy compound to yield a water-insoluble polymer. Also claimed is a method of making the membrane. There are independent claims for a composite polyamide reverse osmosis membrane comprising a microporous support, a polyamide layer on the support and a cross-linked polyfunctional epoxy layer on the polyamide layer, and a method of making such a membrane. The composite polyamide reverse osmosis membrane is preferable made by an interfacial reaction between a polyfunctional amine and an amine-reactive reactant, such as an acyl halide, a sulfonyl halide or an isocyanate. The method of making the membrane involves contacting the membrane support with a solution of the reactants and effecting curing, optionally catalysed by an acid, a base or heat. The microporous support may be a microfiltration membrane of an ultrafiltration membrane.