Influencing Crystal Nucleation by Glass Preparation Method

Amorphous solids exist in a metastable state and tend to change over time, with driving forces towards more thermodynamically stable states, such as the crystalline form. Efforts exist to find tools to kinetically prevent crystallization of glassy materials, for applications including pharmaceuticals. Pharmaceutical glasses may be utilized in an amorphous form due to improvements in solubility and bioavailability, but storage of such forms may lead to crystallization. In exploring crystallization of a typical amorphous pharmaceutical, we find that, even as crystal growth rates remain constant, a thickness-dependence of crystal nucleation is observed in surprisingly thick films (~200 nm). Exploration of this apparent "confinement" effect leads to intriguing influences of preparation on both spin-coated and melt-quenched molecular glasses. This presentation seeks to explain the relationships between preparation conditions and crystal nucleation rates.