Organophosphazenes 27: the Synthesis and Polymerization of (4- Ethenylphenyl)Pentafluorocyclotriphosphazene

Abstract

The synthesis and homopolymerization of a fluorocyclotriphosphosphazene with a directly bonded styrene moiety is presented. A multistep sequence was employed wherein commercially available p-bromostyrene is first converted to 1-(4-bromophenyl)-1-methoxyethene, 4-BrC₆H₄C(OCH₃)CH₂ which in turn is lithiated and added to N₃P₃F₆ to give (4-(1-methoxyethenyl)phenyl)pentafluorocyclotri phosphazene, N₃P₃F₅(4-C₆H₄C(OCH₃)˭CH₂)(2). Addition of tri(n-butyl)tin hydride to 2 followed by elimination of tri(n-butyl)tin methoxide over silica produced the target monomer, (4-ethenylphenyl)- pentafluorocyclotriphosphazene, and N₃P₃F₅(4-C₆H₄CH˭CH₂)(3). The new phosphazene derivatives were characterized by mass spectrometry, NMR (¹H,¹³C,¹⁹F,³¹P) and IR spectroscopy. Radical addition polymerization of 3 resulted in the formation of poly(p-pentafluorocyclotriphosphazenylstyrene)(4). Molecular weights of the new polymer were determined by GPC and membrane osmometry. The GPC data suggested the occurrence of chain transfer in the polymerization. TGA studies showed that 4 exhibits high thermal stability compared to other organophosphazene polymers. The T_g value is significantly greater than that of polystyrene.

GRAPHICAL ABSTRACT

Keywords:

• Fluorocyclophosphazenes
• NMR
• organophosphazene polymerization
• GPC
• TGA

Additional information

Funding

Partial support from the office of Naval Research and the Vermont EPSCoR programs is gratefully acknowledged.