Synthesis of Trifluoromethyl- and Methylphosphazene Polymers: Differences between Polymerization and Initiator/Terminator Properties

A new polyphosphazene, [N=PPh(CF 3 )] n , has been prepared via the PCl 5 -induced cationic polymerization of Me 3 SiN=P(CF 3 )(Ph)Br. In addition, the cationic route has been used to produce [N= PPh(Me)] n with controlled molecular weights and narrow polydispersities. By contrast, the new monomer Me 3 SiN=P(t-Bu)(Ph)F failed to polymerize under any conditions but was used as an initiator and terminator to prepare both mono- and ditelechelic polymers. This monomer was also used to prepare [F(Ph)(t-Bu)P=N(PCl 2 =N)P(t-Bu)(Ph)F] + , which was used as a substrate for reactions with alkoxy and aryloxy groups to yield the hydrolytically stable materials, [R(Ph)(t-Bu)P=N(PR 2 =N)P(t-Bu)(Ph)R 2 ].