Semibatch Emulsion Copolymerization of Butyl Acrylate and Glycidyl Methacrylate: Effect of Operating Variables

Semibatch emulsion copolymerization was carried out to prepare poly(butyl acrylate-co-glycidyl methacrylate) latexes at 75 degrees C, using potassium persulfate as an initiator, sodium dodecylbenzene sulfonate as an emulsifier and sodium bicarbonate as a buffer. The reaction was conducted in three stages; a further stage (called the steady stage, 2 h) was added to the traditionally stages (i.e., feed and seed stages) to improve considerably the monomer conversion. The monomer conversion and particle size distribution were studied by gravimetric and laser light scattering methods, respectively. The effects of variables such as agitation speed, emulsifier concentration, initiator concentration, feeding rate and comonomers ratio were fully investigated based on the monomer conversion-time profiles and the particle size distribution to find the optimized copolymerization conditions. Increasing the agitation speed had a negative effect on the monomer conversion, but reduced coagulation of polymer particles. Monomer conversion could be improved by increasing the initiator or emulsifier contents. Feeding rate increased the polymer particle size sharply; however, it showed no significant effect on conversion. The final conversions were as high as 97-99% and they were recognized to be independent of the comonomers ratios employed. Morphological studies by scanning electron microscopy showed nano-sized isolated particles which were partially aggregated. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 2771-2780, 2010