There is described a polymer blend of a first and second polymer comprising: a) a first polymer of: vinyl (co)polymer; alkyd; urethane acrylic copolymer; polyurethane and/or polyester; b) a second copolymer from: b1) optionally at least 10 wt-% of one or derivatives of itaconic acid and/or isomers thereof; b2) up to 20 wt-% of one or more acid functional (or potentially acid functional) monomer(s) and b3) vinyl monomer(s) where wt % of each monomer (b1 to b3) is based on total (b) and where at least one of the first and second polymer is obtained from an itacon-functional monomer such as itaconic acid and/or its derivatives.