An Investigation of Amorphous and Unique Organic Molecular Structure Via Monodisperse Droplet Evaporation and Spray Drying

Producing solid particles where the size and morphology are controlled is important in many industrial processes including those in the food, cosmetics, and pharmaceutical industries. In the pharmaceutical industry specifically, the purity, size, and internal structure are very important and being able to control all three aspects in one processing step is very beneficial in creating a product. Additionally, research has shown that changing the structure of a pharmaceutical agent can increase the bioavailability of the drug making the ability to control the structure of a particle very important. The work in this thesis focuses on controlling the internal structure of particles formed by monodisperse droplet evaporation and spray drying by observing the crystal structures of the particles produced by both methods and by intentionally altering the crystal structure by the addition of a polymer in particles formed by monodisperse droplet evaporation. Observations of surface morphologies are also performed. Particles were created using a vibrating orifice aerosol generator (VOAG) and a Buchi B290 spray dryer to take advantage of the rapid evaporation achieved by both machines. Dicarboxylic acids and vanillin were chosen as solutes due to their high propensity to crystalize and the possibility to from metastable polymorphs. Experimental results show that both methods of particle formation can produce particles containing metastable polymorphs. The addition of the polymer polyvinylpyrrolidone (PVP), when added in high enough percent, will fully disrupt the crystal structure of a particle making it fully amorphous. Addition of PVP also changed the morphology of the particles in an observable way