Hierarchical Structure of Glucosamine Hydrochloride Crystals in Antisolvent Crystallization

The crystal morphology of glucosamine hydrochloride (GAH) during antisolvent crystallization was investigated in this work. Particles of different shapes, such as plate-like crystals, leaflike clusters, fan-like dendrites, flower-like aggregates, and spherulites, were produced by tuning the type of antisolvents and crystallization operating conditions. The hierarchical structures of GAH crystals tended to be formed in a water + isopropanol mixture. The effects of operation parameters on the polycrystalline morphology were studied, including crystallization temperature, solute concentration, feeding rate of GAH aqueous solution, solvent-to-antisolvent mass ratio, and stirring rate. The evolution process of GAH spherulites was monitored using SEM, indicating a crystallographic branching mode. The crystal habit was predicted to identify the dominant faces. Molecular dynamics simulations were performed and the interaction energy of solute or solvent molecules on crystal surfaces was calculated. The experimental and simulation studies help to understand the branching mechanism and design a desired particle morphology.