An aqueous emulsion comprising at least a covalently bound vinyl oligomer and vinyl polymer, wherein said vinyl oligomer comprises 5 to 85 mol % of vinyl monomers bearing quaternary ammonium ion functional groups or quaternisable amine functional groups and is obtained by a controlled radical polymerisation of at least one vinyl monomer via a reversible addition-fragmentation chain transfer mechanism in solution in the presence of a control agent and a source of free radicals; wherein said vinyl polymer is obtained by emulsion polymerisation of vinyl monomers in the presence of the vinyl oligomer; wherein the weight % ratio of vinyl oligomer to vinyl polymer is in the range of from 0.5:99.5 to 65:35.