Nucleation, crystal growth, nuclei stability, and polymorph selection in supercooled tolbutamide melt.

Nucleation is an essential step of overall crystallization, yet crystal nuclei are elusive to direct observation due to their small size and transient nature. A method for assessing the nuclei size distribution and growth rate based on selective melting/dissolving was developed recently, making use of the rapid heating/cooling rate available in fast scanning calorimetry. The method was first employed to study the nuclei in the polymer poly-L-lactic acid.