Kinetic modeling of a comonomer photopolymerization system using high-throughput conversion data

A kinetic model was developed for copolymerization of (meth)acrylate formulations to optimize both kinetic parameters and predict the kinetics of unknown formulations. This model incorporates free volume theory and reaction diffusion changes in the kinetic constants as a function of conversion and reactivity ratios for the copolymerization events. High-throughput analysis data were collected for two systems as a function of composition and exposure time. Hexyl acrylate (HA) and hexanediol diacrylate (HDDA) show a nonlinear dependence on composition, with the maximum overall conversion occurring at 60 wt % HDDA. In addition, faster photopolymerization is observed as HDDA is added to a pure monoacrylate system but eventually limits the overall conversion in the system. Similar results were found with HDDA and tetrahydrofurfuryl acrylate (THFFA) with the highest conversion observed at 20 wt % HDDA. A model optimization was performed on both systems using a particle swarm optimization protocol to find the kinetic parameters which best fit the analyzed data. These optimizations show similar conversion profiles, and the optimized kinetic parameters were then used to predict conversion for a copolymerization of HA and THFFA. The monotonic increase in conversion as a function of composition is confirmed from the high-throughput data, with an average absolute error of 4.0%. A prediction of a formulation with all three monomers using the original optimized parameters and no further adjustable parameters produces a conversion profile similar to the observed profile with an average error of 5.0%.