An Improved Iterative Method to Obtain Optimal Monomer Addition Profiles in Copolymerizations

Abstract

Controlling the chemical composition distribution (CCD) of copolymers through optimal monomer addition profiles (OMAP) is of great importance for their properties. However, the requirement to know various kinetic parameters of the polymerization often complicates obtaining such addition profiles on a time basis. A simpler approach is to forecast OMAP based on monomer conversions, which only requires the reactivity ratios for solution or bulk polymerizations. For emulsion copolymerization, it's also necessary to include the solubilities of the monomers in both water and polymer. Starting with an OMAP on a conversion basis, one can establish an OMAP on time basis by performing two or three experiments measuring the conversion-time relationships as part of the iterative process. In this paper, an improved procedure is described that requires minimal knowledge of kinetics parameters and therefore is very suitable for monomers where most kinetic parameters are not known, like biobased monomers. The process starts with an initial guess of the kinetics and, within 2–3 iterations, results in a time-based OMAP. Examples are included for solution copolymerizations.