CARBOXYLATED STYRENE-BUTYL ACRYLATE AND STYRENE-BUTADIENE EMULSION COPOLYMERS - MODELING THE DISTRIBUTION OF THE ACID MONOMER BETWEEN SERUM, PARTICLE SURFACE AND THE PARTICLE CORE

The concept of the critical chain length for radical entry Z was used for modelling the rate of carboxylation between the particle surface a nd particle core. An average Z value was computed by a semi-empirical method from the individual Z values for homopolymers. Grafted, buried and water soluble polymerized acid could be computed as well as the mo lecular weight of the grafted and water soluble species. The model was tested on two different systems involving either styrene/butadiene or styrene/butyl acrylate as the main monomers and acrylic acid as the c arboxylated monomer; it gave a good approximation of the actual rate o f grafting and molecular weight. In butadiene containing recipes, gel permeation chromatography (g.p.c.) of the aqueous phase showed an unus ual peak that might be assigned to the exit of butadiene radical follo wed by propagation and particle capture. Copyright (C) 1996 Elsevier S cience Ltd.