the present invention is a method of manufacturing polymer particles . the method includes providing an oil in water emulsion , wherein the oil phase comprises a volatile solvent and at least one water insoluble polymer . the volatile solvent has a solubility of not more than 10 % in water and the water insoluble polymer has a weight average molecular weight of at least 2000 . the water insoluble polymer is soluble in the volatile solvent . the emulsion is supplied to a rotating surface of a rotating surface reactor . the temperature of the rotating surface is maintained at the boiling point of said solvent or greater . the rotating surface of the reactor spins at a speed sufficient to cause the emulsion to spread over the rotating surface as a continuously flowing thin film wherein a vapor phase containing the volatile solvent is removed . the water insoluble polymer particles are then collected as a slurry of polymer particles and water .