| Abstract: | Poly(vinyl alcohols) derived from the product of polymerization of vinyl acetate in methanol have been characterized by various physical and chemical methods before and after NaIO4 cleavage. The 220-MHz 1H-NMR spectra confirm the reliability of NaIO4 titrimetry for estimating 1,2-glycol content and help explain the tendency for viscometry to grossly underestimate the 1,2-glycol content for low molecular weight polymers. The spectra and related chemical evidence indicate that the major endgroups are HOCH2CH2? and CH3CH(OH)CH(OH)CH2? . ß-Hydroxyethyl groups also occur as short chain branches, mainly attached to α carbon atoms in the normal head-to-tail polymer chain sequence. The concentrations of the branch and endgroups depend on polymerization conditions and help explain polymerization “solvent” effects on physical properties. |
