Compositional heterogeneity in partially hydrolysed poly(vinyl alcohol) by reversed phase liquid chromatography

Reversed phase high performance liquid chromatography (HPLC) was employed to elucidate the composition distribution of partially hydrolysed samples of poly(vinyl alcohol) (PVOH), demonstrating that elution across a chromatogram proceeded from higher to lower degree of hydrolysis (DoH). Fractions isolated by preparative HPLC fractionation and characterised by H-1 nuclear magnetic resonance spectroscopy (NMR) were used as HPLC standards to construct a calibration curve of retention time versus DoH, allowing for DoH determination of any PVOH sample once its chromatogram was available. Plots of cumulative and differential distributions as a function of DoH were determined, allowing for comparisons of samples having average DoH in the range 70-90 mol%. A second set of fractions originating from a parent polymer having different molar mass was also isolated to confirm that calibration was not influenced by molar mass or size exclusion effects. (C) 1999 Elsevier Science Ltd. All rights reserved.