The invention pertains to a method for making a methacrylate unit-containing polymer with polydispersity 1.7 and containing at least one cross-linkable functional group comprising a step of radically polymerizing a mixture of ethylenically unsaturated monomers comprising at least 50 mole % of methacrylate monomers to a polymer, in the presence of a) a radical precursor and b) I₂ or a sulfonyl iodide.