Synthesis, Microstructure, and Acidity of Poly(vinylphosphonic acid)

Abstract

Abstract Summary: Vinylphosphonic acid is polymerized at 80 °C by free radical polymerization to give a high‐molecular‐weight polymer ( $\overline M _{\rm w}$ of 6.2 × 10 4 ) as determined by static light scattering. High‐resolution NMR spectroscopy is used to gain microstructure information. Information based on tetrad probabilities is utilized to deduce an almost atactic configuration. In addition, 13 C NMR spectroscopy gives evidence for the presence of head‐to‐head and tail‐to‐tail links. Refined analysis of the 1 H NMR spectra allows for the quantitative determination of the fraction of these links (23.5% of all links). Experimental evidence suggests that the polymerization proceeds via cyclopolymerization of the vinylphosphonic acid anhydride as an intermediate. Titration curves indicate that high‐molecular‐weight poly(vinylphosphonic acid) PVPA behaves as a monoprotic acid. Radical polymerization of vinylphosphonic acid proceeds by cyclopolymerization of its anhydride. magnified image Radical polymerization of vinylphosphonic acid proceeds by cyclopolymerization of its anhydride.