Synthesis of Telechelic Polyphosphazenes via the Ambient Temperature Living Cationic Polymerization of Amino Phosphoranimines

A method for the synthesis of well-defined mono-, di-, and mixed-telechelic polyphosphazenes produced via a living cationic polymerization of phosphoranimines is described. Amino phosphoranimines R-NH(CF₃CH₂O)₂P=NSiMe₃ (R = Ph-, p-BrPh-, p-H₃CPh-, CH₂=CHCH₂-, and CH₂=CHPh-) were synthesized via a reaction between a bromophosphoranimine and the appropriate organic amine. Ditelechelic polymers [R-NH]₂-[Cl₂P=N]_n were prepared by quenching living poly(dichlorophosphazene) chains, [Cl₃P=N(Cl₂P=N)_n-PCl₃] ⁺[PCl₆]^- with small quantities of the amino phosphoranimines. Cationic initiators of the amino phosphoranimines were also generated using PCls and were used to polymerize Cl₃P=NSiMe₃, to give monotelechelic poly(dichlorophosphazenes). In addition, a mixed telechelic system was produced by the termination of an allylamino monotelechelic poly(dichlorophosphazene) chain with a bromoanilino phosphoranimine. In all cases, displacement of the chlorine atoms with sodium trifluoroethoxide yielded hydrolytically stable telechelic polymers with controlled molecular weights and low polydispersities.