Impact of Cooling Profile on Batch Emulsion Solution Crystallization

Abstract

Emulsion solution crystallization can achieve a narrow and predictable crystal size distribution (CSD) when the emulsion droplets are uniform. The crystallization kinetics of emulsion solution crystallization are generally different from those of conventional bulk crystallization. This work characterizes the impact of temperature profile on emulsion solution cooling crystallization. The temperature is controlled by a tubular heat exchanger, and a membrane is used to create an emulsion with controllable droplet size distribution. The crystallization performance is characterized by the dynamic development of the crystal number density and the CSD, which are compared with those of bulk cooling crystallization. The crystal number density is highly sensitive to the cooling profile, and the process behavior is consistent with a system dominated by primary nucleation. Regardless of the cooling profile, secondary nucleation is suppressed in the emulsion with confined crystallization inside the droplets, which results in a narrow CSD. In contrast, secondary nucleation is dominant in bulk crystallization, leading to a broader CSD with a higher crystal number density. The mean crystal length decreases as the batch time increases with emulsion crystallization, which is different from bulk crystallization. A more predictable and narrower CSD can be obtained from emulsion crystallization, but a higher supersaturation or longer batch time is needed in emulsion crystallization to achieve a similar yield when compared to that in conventional bulk cooling crystallization.

In‐Drop Thermal Cycling of Microcrystal Assembly for Senescence Control with Minimal Variation in Efficacy

“…After 7 thermal cycles and a 24 h hold time to reach complete crystallization, 86.3% of drops containing HA‐dopa had at least 1 crystal ( M + ), a 4‐fold improvement than previously reported efficiencies for similar cooling crystallization timescales (Figure S1b, Supporting Information). [ 39,41,42 ] Furthermore, the time for 50% of drops to contain a crystal is 10‐fold faster for HA‐dopa loaded drops, illustrating the drastic effect of HA‐dopa on early nucleation kinetics and considerably improving the practicality of crystallization using droplet microfluidics.…”