Exploring the Limits of Branching and Gel Content in the Emulsion Polymerization of n-BA

The possibility of synthesizing a highly branched poly( n -butyl acrylate) by emulsion polymerization was explored. Branching levels as high as 6.3% were obtained at high temperatures under starved conditions. Gel, which ranged from 53% to 78%, increased with temperature and process time. Highly branched polymers with gel contents of about 70% showed a very good shear resistance. It was found that the polymerization rate decreased with temperature. The mechanisms responsible for this surprising kinetics as well as for the formation of the microstructure were discussed.