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

Abstract

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 β‐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.

In Silico Screening To Achieve Fast Lab-Scale Nitroxide-Mediated Polymerization of n-Butyl Acrylate with Maximal Control over Macromolecular Properties

“…Model-based design for acrylate radical polymerization is also possible upon considering step-wise T j variations and semibatch operation, as recently demonstrated under FRP conditions. ,, In the present work, this is further illustrated under NMP conditions in ( i ) Figure a–f, considering three variable T j profiles, with temperature variations between 383 and 403 K, and with three flat counter cases with fixed T j values of 383, 393, and 403 K, and in ( ii ) Figure a–f, considering three semibatch profiles with nitroxide and one batch counter case.…”

Mechanism-Guided Discovery of Cleavable Comonomers for Backbone Deconstructable Poly(methyl methacrylate)

“…Gradient structures (in controlled radical polymerizations) or compositional drift (in free-radical polymerizations) emerge when one reactivity ratio is >1 and the other <1, with the monomer having the larger reactivity ratio being consumed first. Previous studies have used Monte Carlo simulations to examine copolymer sequences based on reactivity ratios. − This methodology can be extended to model fragment sizes post-degradation in the context of the CC approach. − For example, we conducted simulations involving 2.5% CC loading with a degree of polymerization (DP) of 1000 and plotted the weight-average molar mass ( M w ) of the oligomeric fragments obtained after CC cleavage relative to the M w of the starting copolymer under various reactivity ratio scenarios (Figure A; see Supporting Information for simulation details). The use of M w for plotting conveys information about the largest fragments, which is important for assessing the performance of CCs.…”

Exploring the Kinetics of Solution Polymerization of Butyl Acrylate for Tailoring a Microstructure at Elevated Temperatures

“…Knowledge of acrylate polymerization kinetics has continued to evolve, as summarized in a review by Ballard and Asua . In particular, backbiting, MCR migration, Beta-Scission, and its effect on the average molar mass and microstructure have been investigated. − The kinetics of polymerization of acrylate monomers has been studied by different research groups. ,,,− Numerous advancements have been made in this regard, particularly through the use of electron spin resonance (ESR) spectroscopy and pulsed laser polymerization (PLP) methods. ,,, Different methodologies have been used to report rate coefficients for various reactions, ,− ,,,− e.g., Beta-Scission, ,, chain transfer to solvent, ,, termination of secondary radicals, ,, and termination of tertiary radicals. , …”