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)2PNSiMe3 (R = Ph−, p-BrPh−, p-H3CPh−, CH2CHCH2−, and CH2CHPh−) were
synthesized via a reaction between a bromophosphoranimine and the appropriate organic amine. Ditelechelic polymers [R−NH]2−[Cl2PN]
n
were prepared by quenching living poly(dichlorophosphazene) chains,
[Cl3PN(Cl2PN)
n
−PCl3]+[PCl6]- with small quantities of the amino phosphoranimines. Cationic initiators
of the amino phosphoranimines were also generated using PCl5 and were used to polymerize Cl3PNSiMe3,
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.
Mono- and ditelechelic linear polyphosphazenes, functionalized with a norbornene end group,
were synthesized through the termination of living poly(dichlorophosphazene) with norbornenyl phosphoranimines. These materials were employed as macromonomers for the synthesis of graft copolymers
via the ring-opening metathesis polymerization (ROMP) of the terminal norbornenyl component.
Norbornenyl monotelechelic polyphosphazenes with various molecular weights yielded un-cross-linked
graft copolymers when subjected to ROMP. The ditelechelic polyphosphazenes yielded branched or cross-linked materials due to the multiple reactive sites. In addition, the 5-norbornene-2-methoxy phosphoranimine was polymerized via ROMP to yield materials that consisted of a polynorbornene backbone with
phosphoranimine pendent side groups.
The synthesis of polyphosphazene-co-poly(ethylene oxide) block copolymers with well-defined molecular weights has been accomplished via end-functionalized polymer intermediates. Mono-and diamine-terminated poly(ethylene oxides) (PEO ) (CH 2CH2O)n-CH2CH2-) were used to produce polymerbased phosphoranimines, CH3O-(CH2CH2O)n-CH2CH2-NH(CF3CH2O)2PdNSiMe3 and Me3SiNdP(OCH2-CF3)NH-(CH2CH2O)n-CH2CH2-NH(CF3CH2O)2PdNSiMe3. These were then converted to macroinitiators via reaction with PCl5 to produce CH3O-PEO-NH[(CF3CH2O)2PdNPCl3] + [PCl6]and [Cl3PNdP(OCH2-CF3)NH-PEO-NH[(CF3CH2O)2PdNPCl3] 2+[PCl6]2 -, respectively. These macroinitiators were used to polymerize Cl3PdNSiMe3 in a living manner to produce diblock copolymers of polyphosphazenes with poly(ethylene oxide) or triblock copolymers with poly(ethylene oxide) blocks flanked by polyphosphazene components. In addition, the monophosphoranimine-terminated PEO was employed as a terminator in the living, cationic polymerization of Cl3PdNSiMe3 to produce triblock copolymers with a polyphosphazene block flanked by two poly(ethylene oxide) blocks. Polymers for use as solid-ionic conduction media or hydrogels were produced by nucleophilic replacement of the chlorine atoms along the polyphosphazene segments by methoxyethoxyethoxy units. The ionic conductivities of these materials, after complexation with varying ratios of lithium triflate, ranged from 7.6 × 10 -6 to 1.0 × 10 -4 S cm -1 for a temperature range of 20-80 °C.
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