New synthetic routes towards polyphosphazenes

Abstract

A b s t r a c t : Two new methods for the synthesis of polyphosphazenes are described. The first is based on the catalyzed polycondensation of phosphoranimines using various catalysts and initiators. Certain mechanistic aspects of this process with reactive intermediates are discussed. Linear polymers are formed quantitatively at temperatures around 100 OC in a few hours (the thermal process requires a few days at 200 OC). The second method is based on the direct reaction between phosphonites and phosphinites with silyl azides. This reaction proceeds by phosphine azide intermediates and provides new polyphosphazenes.

Ambient-Temperature Direct Synthesis of Poly(organophosphazenes) via the “Living” Cationic Polymerization of Organo-Substituted Phosphoranimines

“…The growing polymer chains remained active after all the initial monomer 8 had been consumed. A sample of [NdPMe(Et)] n (8) was prepared via the reaction of 1 with PCl 5 in a 40:1 ratio under conditions where all the phosphoranimine had been converted to polymer, as determined by 1 H and 31 P NMR spectroscopy. A portion of this mixture was shown by GPC to have an M n ) 1.1 × 10 4 and PDI ) 1.09.…”

“…[5][6][7] This polymerization proceeds at temperatures near 180-200 °C, to produce a range of poly(aryl/alkylphosphazenes) with molecular weights (M n ) which approach 1 × 10 5 and with polydispersity indices (PDI) of 1.5-3.0. In addition, Matyjaszewski and co-workers have demonstrated that phosphoranimines, such as (CF 3 CH 2 O) 3 PdNSiMe 3 , undergo both anionic 8,9 and cationic 10 CF 3 ) 2 ] n with molecular weights of (1.0-5.0) × 10 4 and with a wide range of polydispersities (1. 3-2.5).…”

“…The most established synthetic route to poly(organophosphazenes) of this type is via the condensation polymerization of N -silylphosphoranimines as developed by Neilson and Wisian-Neilson. − This polymerization proceeds at temperatures near 180−200 °C, to produce a range of poly(aryl/alkylphosphazenes) with molecular weights ( M n ) which approach 1 × 10 5 and with polydispersity indices (PDI) of 1.5−3.0. In addition, Matyjaszewski and co-workers have demonstrated that phosphoranimines, such as (CF 3 CH 2 O) 3 PNSiMe 3 , undergo both anionic , and cationic induced polymerizations at temperatures above 100 °C, to yield [NP(OCH 2 CF 3 ) 2 ] n with molecular weights of (1.0−5.0) × 10 4 and with a wide range of polydispersities (1.3−2.5).…”

Ring-Opening Polymerization—An Introductory Review

“…The poor yields of soluble polymer have proved a major limitation for the commercialization of polyphosphazenes. Thus, alternative, non-ROP, routes have also been investigated [164][165][166][167], albeit with, as yet, limited commercial success. Almost one hundred years after polyphosphazenes were first documented, Allcock's group showed how to convert the base polymer into useful materials (see, e.g., Reference [168]).…”

Controlled Synthesis of Polyphosphazenes with Chain-Capping Agents

“…The first catalyzed/initiated polymerization of a phosphoranimine monomer by fluoride ion was previously reported ( Scheme 1 a) and then extensively investigated [ 33 ]. The successful conversion of these monomers to polyphosphazenes initiated/catalyzed by fluoride anion, trifluoroethoxide anion, and N -methylimidazole was described [ 34 , 35 , 36 ]. Polyphosphazene random and block copolymers with mixed alkoxy/alkoxyether substituents were subsequently prepared by the fluoride/anionic method and characterized [ 37 ].…”