Fabrication of composite particles through single pass using a coaxial tube reactor

Composite particles were prepared by liquid-liquid interfacial crystallization in a coaxial tubular reactor. A microfluidic channel was utilized for controlling particle properties and fabricating composite particles via a single pass in a continuous flow process. Changes in flow patterns with Weber number were investigated by visualizing flow patterns in the reactor; four types of flow patterns were observed. Particle size distributions of sodium chloride (NaCl) in the reactor were optimized by controlling flow patterns. Crystal nucleation rates and growth rates were calculated using the Rosin-Rammler distribution, which is also used in conventional crystallizers. Indomethacin (IMC) crystals with a fibrous morphology were obtained in any of three flow patterns by ultrasonic irradiation of the tube reactor; however, precipitation of IMC did not occur without ultrasonic irradiation. Composite particles of NaCl and IMC were produced by ultrasonic irradiation in a dispersed flow. The process involving dispersed flow could be used to continuously fabricate composite particles in a single pass through the reactor.