[en] If sodium dodecyl sulphate, SDS, is added to a latex of poly(vinyl acetate), PVAc in water, to give an overall SDS concentration greater than 4.5 mM, the polymer latex particles swell reversibly to a final volume of the particles up to fifty times their original volume. 96% of the increase is due to water carried in with the SDS. The swelling is attributed to the formation of polymer micelle complexes (PMCs) along the polymer chains. The charges on these PMCs repel, thus expanding the particles. Entanglement of higher molecular weight chains inhibit swelling beyond an equilibrium value. If, however, the swollen particles are irradiated in a gamma source and then dialysed, they shrink only slightly to approx. forty times the original volume indicating that the charges are attached irreversibly to the PVAc chains. The maximum effect is observed at 12 kGy (dose rate 0.12 Gy/s) and at a molecular ratio PVAc : SDS of 12; both of which indicate that grafting has occurred. The stabilised lattices show a remarkable increase in colloidal stability towards coagulation in sodium chloride solution. The stabilised particles do not coagulate in salt solution 400 times as concentrated as that in which as-prepared unstabilised lattices coagulate. In 2% VAc monomer / 20 mM SDS solution the nonstabilised expanded dose particles contract as the PMCs are displaced by monomer but stabilised particles remain the same size