Abstract: A polymeric composition comprising main chains, side chains attached thereto and crosslinking units between side chains. The main chains comprise a copolymer of two or more ethylenically unsaturated monomers at least one of which contains hydroxyl groups, the side chains comprise lactone chains attached to said hydroxyl groups and the crosslinking units comprise amino resins. The copolymers may be prepared and subsequently modified or the side chain may be attached to an ethylenically unsaturated monomer and the modified copolymer prepared directly by polymerization with other unsaturated monomers. The modified copolymers are crosslinked and cured with an amino resin.