Toward rational
design of tailor-made additives using growth site statistics
Deij MA (Deij, M. A.), Vissers T (Vissers, T.), Meekes H (Meekes, H.),
Vlieg E (Vlieg, E.)
Cryst. Growth & design 7, number 4 (2007) 778-786
Abstract:
Tailor-made additives are generally designed by optimizing the chemical
compatibility between an adsorbing additive and a flat crystalline
surface. Crystal growth, however, mainly takes place at step edges
where growth units incorporate into the advancing step. In this paper,
a new method is introduced that quantifies the importance of all
possible growth site configurations from Monte Carlo crystal growth
simulations, taking the crystalline surface, steps, and other
configurations into account. This allows the identification of growth
site configurations that are good candidates for a blocking strategy
using tailor-made additives. Application to an anisotropic Kossel model
shows that the importance of growth sites at step edges is equal to or
higher than the importance of growth sites at a flat crystalline
surface. As a "real-world" example, aspartame phase II-A, which has a
needle-like morphology, is studied. When comparing the needle side
faces with faces on top of the needle, it turns out that there are a
minor number of growth site configurations that have different
contributions to the growth process. When these configurations are
excluded from the growth process, in a first attempt to simulate the
effect of a habit modifier, the results show a large blocking effect
for flat faces. Rough growing faces, on the other hand, do not seem to
be affected by the exclusion of growth site configurations from the
growth process.