Polymer matrix material

A method of making an ionic conducting membrane comprising:

• providing a polyamide substrate;
• polymerizing upon said polyamide substrate an aqueous solution of
• one or more monomers selected from the group consisting of water-soluble, ethylenically-unsaturated acids and acid derivatives and
• a crosslinking agent, and
• replacing a portion of the water of the aqueous solution with an alkaline solution,
• wherein the membrane is swelled to a thickness upon curing prior to replacing a portion of water of the aqueous solution with the alkaline solution,
• wherein the quantity and concentration of the alkaline solution is selected such that the thickness of the membrane after species replacement deviates from the thickness of the membrane before species replacement by less than about 50% to minimize excessive swelling or shrinking of the membrane.