Properties of poly(phosphazene-siloxane) block copolymers synthesized via telechelic polyphosphazenes and polysiloxane phosphoranimines

Linear A-B, A-B-A, and B-A-B block copolymers containing polyphosphazenes and polysiloxanes were synthesized and characterized. Two methods were used in the synthesis of these novel block copolymers. The first utilized hydrosilylation chemistry to couple monotelechelic polyphosphazenes with commercially available dihydride-terminated poly(dimethylsiloxane) (PDMS). The second involved the termination of living poly(dichlorophosphazene) chains with phosphoranimine-terminated PDMS. The semicrystalline, hydrophobic copolymers, [(CF₃CH₂O)₂P=N]_x -[(Me)₂Si-O]_y, and the water-soluble copolymers, [(CH₃OCH₂CH₂OCH₂ CH₂O)₂P=N]_x-[(Me)₂ -Si-O]_y, were prepared by the linkage of either hydrophobic or hydrophilic organic groups to the polyphosphazene backbone. These materials, with a polyphosphazene content from 19 to 73 mol % (43-90 wt %) were obtained with controlled molecular weights that ranged from 5600 to 108 900 Da. The syntheses, characterization, and physical properties of the linear polyphosphazene-polysiloxane block copolymers are reported.