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

Abstract

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 (D̄H) value of 43 mol% with a 'blocky' hydrophilic PVA (PVA I) with a D̄H 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. © 2006 Society of Chemical Industry.