Abstract: A polymer film comprising anionic groups and 0.008 to 25 mg/g of each of components (a) and (b): (a) a crosslinking agent which is free from fluoro groups and comprises a group of Formula (I); and (b) a non-ionic crosslinking agent; Formula (I) wherein M+ is a cation and * indicates the attachment points to other elements of the crosslinking agent.

Abstract: A polymer film obtainable by polymerising a composition comprising: (a) a compound Formula (I); wherein: R is C1-4-alkyl, NH2 or C6-12-aryl; and M+ is a cation; (b) a monomer comprising at least two polymerisable groups; and (c) a solvent. Also claimed are compositions and processes for making the polymer films.

Abstract: A membrane comprising an anion exchange layer (AEL) and a cation exchange layer (CEL) wherein the CEL is obtainable by a process comprising curing a curable composition comprising a compound of Formula (I): Formula (I) wherein: X is is of the formula —OCnH2n+1 or —OCqH2q?1, wherein n has a value of of 1 to 6 and q has a value of 5 or 6; and m has a value of 1 or 2.

Abstract: A polymer film obtainable by curing a composition comprising a compound of Formula (I) wherein: R? is vinyl, epoxy C1-3_alkylenethiol: n has a value of 1 or 2; m has a value of 1, 2 or 3; M?+ is a cation; wherein X is as defined in the claims; and wherein the molar fraction of the compound of Formula (I) in relation to all curable compounds in the composition is greater than 0.25. Also claimed are compositions, processes membranes and their uses.

Abstract: Ion exchange membranes obtainable by curing a composition comprising: (a) a curable monomer comprising at least one anionic or cationic group; (b) a photoinitiator which has an absorption maximum at a wavelength longer than 380 nm when measured in one or more of the following solvents at a temperature of 23° C.: water, ethanol and toluene; (c) at least one co-initiator; and optionally (d) optionally a curable monomer which is free from anionic and cationic groups; wherein at least one of the curable monomers present in the composition comprises an aromatic group.

Abstract: Ion exchange membranes obtainable by curing a composition comprising: (a) a monomer comprising an aromatic group and at least one polymerisable ethylenically unsaturated group; (b) a photoinitiator which has an absorption maximum at a wavelength longer than 380 nm when measured in one or more of the following solvents at a temperature of 23° C.: water, ethanol and toluene; and (c) at least one co-initiator.

Abstract: Bipolar membranes (BPMs) comprising a cation exchange layer (CEL) and an anion exchange layer (AEL) wherein the colour properties of the CEL are visibly different to the colour properties of the AEL. The CEL and the AEL are easily distinguishable so that a stack of membranes comprising the BPMs can be built fast and without mistakes in layer order.

Abstract: A stack of ion exchange membranes suitable for water purification comprising a plurality of anion exchange membranes (AEMs) and a plurality of cation exchange membranes (CEMs), wherein the colour properties of the AEMs are visibly different to the colour properties of the CEMs. The invention also provides a process for making membrane stacks in which the likelihood of there being two consecutive membranes of like charge is reduced. Furthermore, it is easy to identify whether there are two consecutive membranes of like charge present in the stacks.