Aqueous oligomer / polymer emulsion with cationic functionality

An aqueous emulsion comprising a substantially insoluble vinyl oligomer in the form of a block copolymer comprising at least blocks [A]x[B]y, where at least block [A] is obtained by a controlled radical polymerisation of at least one ethylenically unsaturated monomer via a reversible addition-fragmentation chain transfer (RAFT) mechanism in solution in the presence of a control agent and a source of free radicals;

• and wherein the block copolymer comprises:
• 5 to 90 wt % of block [A] comprising:
• i) 10 to 100 mol % of ethylenically unsaturated monomers bearing quaternary ammonium ion and/or quaternisable amine functional groups;
• ii) 0 to 90 mol % of ethylenically unsaturated monomers bearing water-dispersing or potentially water-dispersing functional groups;
• iii) 0 to 50 mol % of C1 to C18 alkyl(meth)acrylates and/or styrenic monomers;
• iv) 0 to 10 mol % of ethylenically unsaturated monomers different from those from i), ii) and iii);
• where i), ii), iii) and iv) add up to 100 mol %, and
• 10 to 85 wt % of block [B] comprising:
• i) 0 to 10 mol % of ethylenically unsaturated monomers bearing quaternary ammonium ion and/or quaternisable amine functional groups;
• ii) 0 to 5 mol % of ethylenically unsaturated monomers bearing water-dispersing or potentially water-dispersing functional groups;
• iii) 50 to 100 mol % of C1 to C18 alkyl(meth)acrylates and/or styrenic monomers;
• iv) 0 to 50 mol % of ethylenically unsaturated monomers different from those from i), ii) and iii);
• where i), ii), iii) and iv) add up to 100 mol %;
• where [A] has an average degree of polymerisation x, where x is an integer in the range of from 3 to 80;
• where [B] has an average degree of polymerisation y, where y is an integer >3.