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(CF<INF>3</INF>CH<INF>2</INF>O)<INF>2</INF>P&dbd;NSiMe<INF>3</INF> (R = Ph−, p-BrPh−, p-H<INF>3</INF>CPh−, CH<INF>2</INF>&dbd;CHCH<INF>2</INF>−, and CH<INF>2</INF>&dbd;CHPh−) were synthesized via a reaction between a bromophosphoranimine and the appropriate organic amine. Ditelechelic polymers [R−NH]<INF>2</INF>−[Cl<INF>2</INF>P&dbd;N]<INF>n</INF><INF></INF> were prepared by quenching living poly(dichlorophosphazene) chains, [Cl<INF>3</INF>P&dbd;N(Cl<INF>2</INF>P&dbd;N)<INF>n</INF>−PCl<INF>3</INF>]⁺[PCl<INF>6</INF>]^- with small quantities of the amino phosphoranimines. Cationic initiators of the amino phosphoranimines were also generated using PCl<INF>5</INF> and were used to polymerize Cl<INF>3</INF>P&dbd;NSiMe<INF>3</INF>, 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.