Curable Compositions and Membranes

An ion exchange membrane obtainable from curing a composition comprising:

• (i) a curable compound comprising at least two (meth)acrylic groups and a sulphonic acid group and having a molecular weight which satisfies the equation:
• MW<(300+300n)
• wherein:
• MW is the molecular weight of the said curable compound;
• and
• n has a value of 1, 2, 3 or 4 and is the number of sulphonic acid groups present in the said curable compound;
• optionally (ii) a curable compound having one ethylenically unsaturated group;
• optionally (iii) a curable compound comprising at least two (meth)acrylic groups and being free from sulphonic acid groups;
• optionally (iv) a radical initiator;
• and
• (v) a solvent;
• wherein the composition comprises:
• (a) 2 to 80 wt % of component (i), 1 to 70 wt % of component (ii), 0 to 40 wt % of component (iii), 0 to 10 wt % of component (iv);
• and 15 to 70 wt % of component (v);
• or
• (b) 5 to 75 wt % of component (i), 0 to 60 wt % of component (ii), 0 to 30 wt % of component (iii), 0.1 to 10 wt % of component (iv);
• and 20 to 45 wt % of component (v);
• wherein the molar fraction of curable compounds comprising at least two (meth)acrylic groups, relative to the total number of moles of curable compounds present in the composition, is at least 0.25.