Effect of ultrasonic pretreatment on emulsion polymerization of styrene

• Emulsion polymerization of styrene was intensified using ultrasound pretreatment.
• Ultrasound irradiation as short as 1 min drastically improved monomer dispersion.
• Ultrasound pretreatment gave increase of the polymerization rate even under the slow agitation.
• Kinetics of ultrasound assisted emulsion polymerization was discussed in detail.
• Fine dispersion resulted in the increase of polymer particle diameter due to partition equilibrium.

This study investigated the effect of pretreatment of ultrasonic irradiation on emulsion polymerization of styrene to propose a process intensification method which gives high conversion, high reaction rate, and high energy efficiency. The solution containing styrene monomer was irradiated by a horn mounted on the ultrasonic transducer with the diameter of 5 mm diameter and the frequency of 28 kHz before starting polymerization. The pretreatment of ultrasound irradiation as short as 1 min drastically improved monomer dispersion and increased reaction rate even under the agitation condition with low rotational speed of impeller. Furthermore, the ultrasonic pretreatment resulted in higher monomer concentration in polymer particles and produced larger polymer particles than conventional polymerization without ultrasonic pretreatment.