Fluorinated copolymers are prepared via copolycondensation polymerization in a process comprising reacting A) a telechelic fluoroazido compound of formula N3(Y)p—(CH2)n—R—(CH2)m—(Y)pN3, wherein Y is SO, SO2, C6H4, or CO, p=0 or 1, n and m are independently 1 to 4, and R is selected from the group consisting of i) a C3-C10 fluoroalkylene group, ii) a C3-C10 fluoroalkoxylene group, iii) a substituted aryl group, iv) an oligomer comprising copolymerized units of vinylidene fluoride and perfluoro(methyl vinyl ether), v) an oligomer comprising copolymerized units of vinylidene fluoride and hexafluoropropylene, vi) an oligomer comprising copolymerized units of tetrafluoroethylene and perfluoro(methyl vinyl ether), and vii) an oligomer comprising copolymerized units of tetrafluoroethylene and a hydrocarbon olefin with B) a telechelic diyne or dinitrile compound in the presence of copper halide catalyst.