Emulsion polymerization of vinylidene fluoride polymers in the presence of trichlorofluoromethane as chain transfer agent

In a process for preparing a high molecular weight vinylidene fluoride polymer by the emulsion polymerization of vinylidene fluoride monomer in a stirred, aqueous reaction medium which comprises charging to a heated reactor water, and with agitation from about 0.05 to 0.5 weight percent, based on the total amount of monomer used in the process, of a water-soluble fluoroalkyl surfactant capable of emulsifying both the initiator and the reaction mass for the duration of the polymerization, and sufficient monomer, at least about 50 mole percent of which is vinylidene fluoride, to obtain a pressure in the reactor of at least about 300 psig, adding from about 0.5 to 6.0 grams of initiator per kilogram of monomer to start the polymerization, and feeding additional amounts of monomer and initiator to the reacton medium during the polymerization process, the improvement which comprises including in the polymerization process from about 0.5 to 8.0 mole percent, based on the total amount of monomer used in the process, of trichlorofluoromethane as a chain transfer agent.