Cationic homo- and copolymerization of fluorophosphoranimines as an ambient temperature synthetic route to poly(fluorophosphazenes), [N=PF(R)]n, with controlled architectures

James M. Nelson, Harry R. Allcock, Ian Manners

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Abstract

The PCl5-induced polymerization of the fluorophosphoranimine PhF2P=NSiMe3 at ambient temperatures (35 °C) yields the poly(fluorophosphazene) [N-PF(Ph)]n This THF-soluble product was treated with an excess of sodium triflouroethoxide in refluxing dioxane to replace the fluorine atoms by trifluoroethoxy groups and generate the known hydrolytically stable polymer [N=PPh(OCH2CF3)]n. The molecular weights in this system can be controlled by variation of the monomer to initiator ratios, and polydispersities for [N=PPh(OCH2CF3)]n are in the range of 1.05-1.32. In order to explore the synthetic utility of [N=PF(Ph)]n, the polymer was treated with Grignard or alkyllithium reagents such as MeLi, n-BuLi, or p-tolylmagnesium bromide to produce the poly(organophosphazenes) [N-PPh(R)]n (R = Me, n-Bu, p-tolyl). Complete replacement of the fluorine atoms using alkyl/aryllithium reagents induced a significant decline in molecular weights However, treatment of [N=PF(Ph)]n with a 0.5 molar equiv of MeLi at -78 °C, followed by replacement of the remaining fluorine atoms with NaOCH2CF3 in refluxing dioxane, produced the mixed-substituent polyphosphazene {[N-PPh(OCH2CF3)0.5(Me)0.5] y} with Ma = 2.4 × 104 (PDI = 1.10) The phosphoranimine PhF2P=NSiMe3 also reacts at 35 °C with "living" poly-(dichlorophosphazene). (N=PCl2)n, to produce the block copolymer {[N=PCl2]n[N=PPh(F)]m}. Halogen replaoement by NaOCH2CF3 in refluxing dioxane produced the known hydrolytically stable block copolymer {[N=P(OCH2CF3)2]n[N=PPh(OCH 2CF3)]m} with Wn = 4.5 × 104 (PDI = 1.30).

Original languageEnglish (US)
Pages (from-to)3191-3196
Number of pages6
JournalMacromolecules
Volume30
Issue number11
DOIs
StatePublished - Jun 2 1997

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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