Patent ID: 7317050

Claim:
A process for the preparation of a Nth generation block copolymer by radical polymerization, N being greater than or equal to 2, which comprises: a first stage of radical polymerization, to form the first generation polymer, which comprises: (a) the preparation of a mini-emulsion comprising: at least one ethylenically unsaturated monomer, at least one control agent selected from the group consisting of xanthates, dithiocarbamates, thioether-thiones, xanthates comprising phosphorus and optionally fluorine and dithiophosphoric acid esters, an aqueous solution, at least one surfactant, and a cosurfactant, and (b) the reaction of said mini-emulsion, in the presence of a source of free radicals, at a sufficient temperature and/or for a sufficient time to form polymers, followed by N−1 stages of radical polymerization, each of these stages being carried out from a mini-emulsion, according to the first stage, comprising: at least one ethylenically unsaturated monomer, the polymer obtained in the preceding radical polymerization stage, optionally an aqueous solution, and optionally a surfactant, and (ii) the reaction of said emulsion, in the presence of a source of free radicals, at a sufficient temperature and/or for a sufficient time to form polymers, the ethylenically unsaturated monomer or monomers being such that the block formed at this stage is different in nature from the block formed in the preceding stage.