Modeling of an Oxygen Threshold in Aqueous Free Radical and RAFT Polymerization Reactions

Fluence Analytics recently teamed up with its academic research partner, Tulane PolyRMC, to investigate the complex role that oxygen (O2) plays during both free and controlled radical polymerization reactions in an aqueous medium with ACOMP. It is common knowledge that oxygen stops free radical polymerizations, and this study found that the polymerization reactions stopped abruptly at the threshold concentration of oxygen. Many research groups have studied the role of O2 in polymerizations, but there still remains much uncertainty about O2 and reactions, as well as its ability to function as an inhibitor and a promoter of polymerization reactions.

Reaction media are typically deoxygenated prior to initiation to avoid undesired inhibition by the presence of O2. Moreover, many research groups have developed new techniques for oxygen tolerant reactions to address in situ deoxygenation. However, most of these techniques depend on extensive modeling, and the lack of extensive experimental data is a huge barrier to developing these kinetic models. In such instances, ACOMP is an extremely valuable tool because it provides online, continuous polymerization reaction data. This work uses controlled O2 flow into the reactor and the continuous multi-characteristic data from ACOMP to show the detailed effects of O2 on acrylamide and sodium styrene sulfonate during radical and RAFT polymerizations. This work is not intended to probe polymerization systems resistant to O2, but rather to present detailed experimental results and kinetic modeling concerning the O2 threshold phenomenon, in order to stimulate further experimentation and discussion in this area.

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