Synthesis of Core/Shell Latexes in a Continuous Stirred Tank Reactor

The feasibility of obtaining core/shell (poly(butyl acrylate-butadiene)/poly(methyl methacrylate)) latexes in a continuous stirred tank reactor was investigated. The effect of mean residence time, premixing of the reactants, nitrogen purge, core/shell ratio, and initiator type and concentration on the kinetics was studied. It was observed that neither the nitrogen purge nor the premixing significantly affected monomer conversion. On the other hand, initiators giving hydrophobic radicals are highly efficient at polymerizing the monomer. Furthermore, the grafting efficiency of the shell polymer on the core was analyzed, and higher grafting was found when the shell proportion increased. The morphology and the performance as impact modifiers of these core/shell latexes were compared with those of conventional products synthesized by a semibatch process. Similar coverage level and comparable properties to the impact performance were obtained.