Polyphosphazenes: Telechelic polymers and copolymers

The living, cationic polymerization of halogenated phosphoranimines (X ₃P=NSiMe₃, XR₂P=NSiMe₃ where X = halogen) allows the synthesis of well-defined polyphosphazenes, [R₂P=N] _n. This ambient temperature polymerization route can produce polyphosphazenes with controlled architectures that include star polymers, telechelic (end functionalized) polymers, and block and graft copolymers. The work described in this thesis includes the synthesis and characterization of novel telechelic polyphosphazenes and copolymers containing polyphosphazenes with organic and inorganic polymers. Specifically, this research focuses on (1) telechelic polyphosphazenes synthesized via the utilization of trisorganophosphoranimines (R₃P=NSiMe₃) as initiators and/or terminators in the living cationic polymerization of trichlorophosphoranimine (Cl₃P=NSiMe ₃), (2) the synthesis of block copolymers of polyphosphazenes and poly(ethylene oxide), poly(dimethylsiloxanes), and polystyrene through polymeric based phosphoranimines, (3) the synthesis of polynorbornene- graft-polyphosphazene and polystyrene-graft-polyphosphazene copolymers from telechelic polyphosphazenes, and (4) the investigation of the polymerization of fluoro based phosphoranimines such as FR₂P=NSiMe ₃.; Chapter 2 is a description of the synthesis of well-defined mono-, di-, and mixed-telechelic polyphosphazenes produced via the living cationic polymerization of phosphoranimines. Trisorganophosphoranimines (R₃P=NSiMe ₃) were synthesized via a reaction between a bromo-phosphoranimine (BrR ₂P=NSiMe₃) and an amino or alkoxy functional group. These phosphoranimines were then used as initiators and/or terminators in the living polymerization of polyphosphazenes. Ditelechelic polymers R′ -[R₂P=N]_n-R′ were prepared through the termination of living poly(dichlorophosphazene) chains, [(Cl ₂P=N)_n-PCl₃]+[PCl₆] −, with small quantities of a trisorganophosphoranimine. Monotelechelic polyphosphazenes were produced by converting the trisorganophosphoranimines into cationic initiators through a reaction with PCl₅. This initiator was then used to polymerize Cl₃P=NSiMe₃, which resulted in the formation of monotelechelic poly(dichlorophosphazenes).; The synthesis and characterization of linear A-B, A-B-A, and B-A-B block copolymers containing polyphosphazenes and polysiloxanes are described in Chapter 3. 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. Semi-crystalline, hydrophobic copolymers, [(CF₃CH₂O)₂P=N]_x-[(Me)₂Si-O] _y, and water-soluble copolymers, [(CH₃OCH₂CH ₂OCH₂CH₂O)₂P=N]_x-[(Me) ₂Si-O]_y, were prepared by altering the pendent group on the polyphosphazene backbone.; Chapter 4 covers the synthesis of polyphosphazene-co-poly(ethylene oxide) block copolymers with well-defined molecular weights. The synthesis of these materials was accomplished via the use of phosphoranimine terminated polyethylene oxide). (Abstract shortened by UMI.)...