KINETIC STUDY ON THE INTER-MOLECULAR AND INTRA-MOLECULAR ACETALIZATION REACTIONS OF POLYMERIC REACTANTS

Inter-and intramolecular acetalizations of poly(vinyl alcohol) (PVA) carrying one or two terminal aldehyde groups were carried out in aqueous solutions as well as in dimethyl sulfoxide (Me2SO) solutions over a wide range of the polymer concentration. The observed rate constant for intermolecular acetalization was in both the solutions independent of the polymer concentration and not significantly different from that for the acetalization of a conventional PVA with aldol, a homologous low molecular weight aldehyde. The results strongly suggest that the polymer coils interpenetrate rather freely with each other in concentrated solutions even of Me2SO which is a good solvent of PVA (water is almost a 0 solvent of PVA). This finding is in agreement with the theory predicting that the excluded volume effect may not be large enough to be detectable under the experimental conditions of this study. In addition, the observed OH concentration effective for the intramolecular acetalization was compatible with that predicted by the statistics of polymer chains. © 1979, American Chemical Society. All rights reserved.