The influence of cavitation radicals on the suspension polymerization of n‐butyl methacrylate during ultrasonic emulsification

The influence of cavitation‐generated free radicals on the suspension polymerization of n‐butyl methacrylate under ultrasonic irradiation was investigated experimentally and by kinetic modeling. A kinetic model of radical polymerization was proposed, considering the interaction of free radicals generated in cavitation bubbles with both monomer molecules and free radicals formed within the monomer droplets. It was found that the primary contribution to the polymerization acceleration come from cavitation radicals generated inside the monomer droplets, whereas the impact of cavitation radicals formed in the dispersion medium decreases as the fraction of monomer in the mixture decreases. Increasing the concentration of cavitation radicals was shown to lead to a reduction in the average chain length and the dispersity of terminated chains. It was demonstrated that the computational results are in good agreement with experimental data. Highlights Kinetic model for suspension polymerization in ultrasonic field is proposed. Impact of cavitation radicals on suspension polymerization kinetics is studied. Chain length and dispersity decrease with increasing amount of cavitation radicals. Schematic representation of suspension polymerization with ultrasonic emulsification (left), conversion and average chain length evolution over time for different concentration of cavitation radicals (right).