31P MAS NMR Spectroscopy of Hexachlorocyclotriphosphazene at Different Stages During Thermal Ring-Opening Polymerization

Abstract

Thermal ring-opening polymerization of hexachlorocyclotriphosphazene was probed using 31 P magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The spectrum of unreacted hexa- chlorocyclotriphosphazene was compared with the spectra of a reaction mixture at 3, 8 and 17.5 h of polymerization. Signals from trimer, oligomer, polymer and hydrolysis products were identified in the spectra and used to observe changes in the mixture during polymerization. The signal of poly(dichlorophosphazene) exhibits a complex behavior where ten individual components were observed and ana- lyzed by deconvolution. These lines were preliminarily assigned to species with differing chain lengths based on their chemical shifts and relative intensities. This work shows that 31 P MAS NMR has the potential to provide quantitative information about the rates of chain propaga- tion and cross-linking during thermal ring-opening polymerization.