Interpolymers of 1-99 mol % vinyl fluoride and 99-1 mol % of at least one highly fluorinated monomer such as tetrafluoroethylene are disclosed. The interpolymers are characterized by the presence of ionic end groups and are prepared by polymerizing VF and fluorinated monomer in water with water-soluble free-radical initiators such as azoamidine initiators or persulfate initiators at temperatures within the range of 60 to 100° C. and reactor pressures within the range of 1 to 12 MPa (145 to 1760 psi). The invention further provides for protective self-supporting films and coatings formed from nonaqueous dispersions of the interpolymers, both for use on the surfaces of substrates including metal, plastic, ceramic, glass, concrete, fabric and wood.