Crystallization and Phase Transformation Kinetics of Suberic Acid Particles Formed via Monodisperse Droplet Evaporation

In order to effectively deliver an Active Pharmaceutical Ingredient (API), pharmaceutical companies rely on specific particle properties including size, morphology, and structure to achieve the desirable drug performance. This thesis utilizes monodisperse droplet evaporation technology to determine the morphology, internal structure, and phase transformation kinetics for particles formed from the model API, suberic acid, and suberic acid/PVP solutions. Particles are formed from a vibrating orifice aerosol generator (VOAG). The suberic acid particles formed were determined to be a new, unknown polymorph, denoted γ-suberic acid. Over time, γ-suberic acid transitions to the stable polymorph, α-suberic acid. The suberic acid particles formed are round with a small dimple, but suberic acid/PVP particles do not exhibit this dimple and are much smoother. Over time, the morphology of the suberic acid/PVP particles does not drastically change, but suberic acid particles lose the dimple and become much more wrinkled. Particles formed from an initial solution of 50 wt% suberic acid 50 wt% PVP were determined to be partially amorphous and partially crystalline, specifically a combination of the alpha and gamma polymorphs. Over time, the particles transition to more crystalline. Particles formed from an initial solution of 31.25 wt% suberic acid 68.75 wt% PVP were determined to be fully amorphous. Over time, they also transition to more crystalline, specifically the alpha polymorph. However, while the particles transition to crystalline, the morphology does not change. A new suberic acid polymorph was observed, thereby expanding the polymorph space and knowledge available to industrial companies and research facilities and institutes. In addition, the observed results show that less stable forms observed in suberic acid particles produced via monodisperse droplet evaporation transform to the more stable form over time, which can affect the shelf life of a potential drug