Abstract: The present invention relates to a method to prepare a polymer dispersion using an aqueous substantially surfactant-free emulsion polymerization process comprising a seed and a feed stage, in which seed stage at least one ethylenically unsaturated monomer, having a water-solubility of at least 0.3 g/l at polymerization conditions, is polymerized in the presence of an addition fragmentation chain transfer agent and a hydrophilic free radical initiator to form a seed polymer that is substantially insoluble in water and in which feed stage at least one ethylenically unsaturated feed monomer is added to the seed polymer to form polymer particles. With this method a polymer dispersion can be obtained having at least 25 wt. % solid contents in combination with an average polymer particle size smaller than or equal to 300 nm.

Abstract: The invention pertains to a polymer obtainable from the steps: polymerizing a mixture, that is substantially free or organic solvents, of ethylenically unsaturated monomers which consist for at least 70% of methacrylates, and which comprises specific chain transfer agents, ?-methylstyrene dimer being preferred, to form a first polymer, aqueous emulsion polymerizing a mixture comprising ethylenically unsaturated monomers in the presence of the first polymer to form a dispersion of a water-insoluble second polymer, wherein these steps are preferably performed in the absence or the substantial absence of a surfactant.

Abstract: The invention pertains to a polymer obtainable from the steps: