Reactive synthetic membranes have been synthesized from a porous polypropylene substrate and a variety of methacrylate monomers using the interpenetrating polymer network technique, and subsequently functionalized to anion exchangers. The chemical composition of these membranes can be controlled in the synthesis stage by varying the monomer ratio or by incorporation of new monomers with the desired properties. The influence of the membrane composition and the type of functionalization reagent is discussed with respect to membrane characteristics such as anion transport, selectivity and water uptake.