No abstract

The mechanism of polymorph selection is still not fully understood in crystallization. This study demonstrates the impact of Taylor vortex flow on the crystallization and polymorph selection of l-glutamic acid as an organic model compound. Our results show that amorphous intermediates preceded the formation of a crystalline phase. The morphology of these amorphous precursorsranging from spherical, oval, and ellipsoidal to irregular shapeswas governed by the velocity of the Taylor vortex flow. We attribute this observation to a transient liquidlike state of the amorphous precursor; simulations indeed corroborated this assumption as the morphology of droplets of a liquidlike precursor varies with the velocity of fluid motion accordingly. The phase selectivity depended on the intensity of the Taylor vortex flow. We found that the metastable α-form crystallized at low Taylor numbers, whereas the thermodynamically stable β-form was obtained at high Taylor numbers, suggesting an impact of Taylor vortex flow on the amorphous-to-crystalline rearrangement of the intermediates. Moreover, a critical value of the Taylor number as Ta ∼ 3636 was determined, which triggered the fast formation of the β-polymorph. We assume that the high shear rate and mass transfer of Taylor vortex flow facilitate the phase transformation from the α- to the β-polymorph.

No abstract

No abstract

No abstract