Heterogeneous, co-continuous copolymers of vinylidene fluoride

The invention relates to a heterogeneous, co-continuous copolymer composition of vinylidene fluoride and at least one other comonomer. Preferred comonomers are hexafluoropropylene and perfluoroalkylvinyl ether. The co-continuous morphology is provide by first forming a first phase polymer, then adding one or more comonomers before half of the original monomer stream has been added, and at an effective level to cause phase separation of the copolymer. The co-continuous morphology provides a means for incorporating a high level of comonomer into the copolymer with little or no adverse effect on the melting temperature. The morphology also provides the copolymer composition with a unique combination of properties, including a high melting point, good flexibility and good low temperature impact resistance. The unique properties of the polymer make it useful in end-use application where those properties provide performance advantages, such as in the wire and cable market, and in oil and gas applications.