Abstract:
The solubility parameters, roughening temperatures and edge free energies
have been measured as a function of temperature and interpreted for
n-C23H48 and n-C25H52 crystals.
The crystals have been grown from solutions consisting of n-hexane and
toluene mixtures. The dissolution
enthalpy is used to determine the strongest bond in the bulk of the
crystal Phi(str)(bulk) and the roughening temperature is used to determine
the
strongest bond in the crystalline interface Phi(str)(int). The ratio
of these two bonds is called the wetting kappa of the crystalline interface.
It turns out
that the solutions containing mixtures of n-hexane and toluene behave
according to a regular solution, which follows directly from thermodynamics
with the use of a mean field approach. The strongest bond in the bulk
of the crystal has the same dependence on the composition of the solution
as
the dissolution enthalpy. In contrast with this, the strongest bond
in the interface stays approximately constant and, therefore, the dependence
of the
wetting re on the composition of the solution follows that of the enthalpy
of dissolution. (C) 1998 Elsevier Science B.V. All rights reserved.