Exploiting (Multicomponent) Semibatch and Jacket Temperature Procedures to Safely Tune Molecular Properties for Solution Free Radical Polymerization of n-Butyl Acrylate

Free radical polymerization (FRP) of acrylates is under conventional lab-scale batch conditions characterized by strong nonisothermicity. Hence, side reactions with a high activation energy such as beta-scission are highly relevant already at intermediate temperatures (313-333 K), broadening the log-molar mass distribution and decreasing the average molar masses. To avoid thermal runaway, one can design jacket temperature profiles or exploit semibatch reactor operations. Model-based design with stochastic solvers is a strong tool to support the identification of optimal reactor settings although rarely applied upon mutually addressing reactor temperature changes and concentration variations due to (multicomponent) feeding strategies. Here such coupled design is performed for lab-scale solution FRP of n-butyl acrylate, benefiting from i) many inputted kinetic parameters (e.g., Arrhenius parameters) that have been benchmarked based on individual experimental techniques, ii) previous kinetic Monte Carlo validation under batch nonisothermal conditions including a prediction of reactor temperature extrema; and iii) systematic screening of semibatch operations in combination with flat and stepwise (average) jacket temperature profiles. It is demonstrated that many molecular properties are safely within hand for different total batch times, taking 2,2 '-azobis(2-methylpropionitrile) as initiator. The model for viscosity control is also employed, expanding the traditional output of FRP simulations.