Tunable linear fluoropolymers

A method of preparing a fluoropolymer comprising:

• preparing a polymerization reaction mixture comprising a diene of formula VII with an α,ω-iodoperfluorocarbon of formula VIII:
• and reacting the polymerization reaction mixture with sodium dithionite, thereby creating a fluoropolymer comprising repeat units according to formula I, Ia, or Ib:
• wherein:
• each R1 is independently a divalent linker;
• each R3 is independently H, alkyl, alkenyl, alkynyl, alkoxy, allyl, aryl, heteroaryl, alkylthio, disulfide, OH, SH, SeH, CN, amino, carboxy, ester, thioester, amide, azide, phosphine, halogen, nitro, carbonyl, silyl, or boron;
• and
• n is an integer from 1-100.