Polytypic Transition of n-Hexatriacontane during Solution Crystallization

The crystallization process of n-hexatriacontane (n-C36H74) was investigated by means of micro-FTIR spectroscopy. From the results of in-situ oblique IR transmission measurements, it was confirmed that single crystals of the M011 modification exhibited a polytypic transformation during solution growth. At the initial stage of the crystallization, single crystals appeared as the single-layered polytype (Mon). The overgrowth of the double-layered polytype (Orth II) took place subsequently on the (001) face of the single crystal. After that, the single crystal gradually transformed into a single crystal of the Orth II type through a solution-mediated phase transition. It was suggested that the transformation from Mon to Orth II was caused by a drop in the supersaturation of the solution.