Effect of Confinement on Crystallization Above and Below T_g in Small Molecule Glasses

The unique properties of small molecule organic glasses offer a wealth of applications. For example, solubility challenges in pharmaceuticals may be overcome via amorphous packing. However, thermodynamic forces eventually lead to the crystallization of these systems, and efforts to improve physical stability are important. Literature suggests a potentially useful role of confinement, commonly investigated using controlled pore glass, on increasing stability against crystallization in small molecule glasses. This work is primarily limited to experiments performed at typical storage temperatures, well below the glass transition temperature. At these temperatures, crystallization may occur via the diffusionless growth mode, where growth rates are faster than anticipated based on diffusion constants. Using two methods to confined a typical amorphous pharmaceutical (indomethacin), we find that, above the glass transition, diffusion-limited growth is not significantly impacted by confinement, while we continue to find evidence of increased stability below the glass transition temperature. This result is repeated across confinement methods including nanoparticle packings (via Capillary Rise Infiltration) and thin films (via spin coating from dilute solutions).