Premium
Diffusion‐controlled and `diffusionless' crystal growth: relation between liquid dynamics and growth kinetics of griseofulvin
Author(s) -
Li Fang,
Xin Junbo,
Shi Qin
Publication year - 2021
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576720014636
Subject(s) - crystal growth , supercooling , diffusion , crystallization , thermodynamics , crystal (programming language) , amorphous solid , relaxation (psychology) , glass transition , materials science , growth rate , chemistry , chemical physics , crystallography , organic chemistry , physics , mathematics , psychology , social psychology , geometry , computer science , programming language , polymer
Understanding how liquid dynamics govern crystallization is critical for maintaining the physical stability of amorphous pharmaceutical formulations. In the present study, griseofulvin (GSF), a classic antifungal drug, was used as the model system to investigate the correlations between crystal growth kinetics and liquid dynamics. The temperature dependence of the kinetic part of the bulk crystal growth in a supercooled liquid of GSF was weaker than that of the structural relaxation time τ α and scaled as τ α −0.69 . In the glassy state, GSF exhibited the glass‐to‐crystal (GC) growth behavior, whose growth rate was too fast to be under the control of the α‐relaxation process. Moreover, from the perspective of τ α , the GC growth of GSF also satisfied the general condition for GC growth to exist: D / u < 7 pm, where D is the diffusion coefficient and u the speed of crystal growth. Also compared were the fast surface crystal growth rates u s and surface relaxation times τ surface predicted by the random first‐order transition theory. Here, the surface crystal growth rate u s of GSF exhibited a power‐law dependence upon the surface structural relaxation time: u s ∝ τ surface −0.71 , which was similar to that of the bulk growth rate and τ α . These findings are important for understanding and predicting the crystallization of amorphous pharmaceutical solids both in the bulk and at the surface.