Preparation and characterization of colloidal dispersions of vinyl alcohol-vinyl acetate copolymers: application as stabilizers for vinyl chloride suspension polymerization

Well‐defined colloidal dispersions of vinyl alcohol–vinyl acetate copolymers (PVAs) with different degrees of hydrolysis (DH) were prepared by a coacervation technique. Colloidal particles in the size range 150–250 nm, with an acetate‐rich core and a hydrophilic PVA corona, were obtained using a combination of a hydrophobic PVA (PVA II) having an average DH ($\overline{DH}$) value of 43 mol% with a ‘blocky’ hydrophilic PVA (PVA I) with a $\overline{DH}$ value of 72 mol%. The core–shell structure of these particles was demonstrated using 1H NMR and using fluorescence‐labelled PVA I. The stabilization efficiency of PVA I and PVA II and their combination was examined for 1‐chlorobutane–water emulsions, as a ‘model solvent’ for vinyl chloride–water emulsions. Preliminary tests of vinyl chloride suspension polymerization confirmed the beneficial effect of PVA I and PVA II combinations as stabilizers on the granulometry and the porosity specifications of the poly(vinyl chloride) grains. Copyright © 2006 Society of Chemical Industry