INTERFACIAL FREE-ENERGIES AND CRYSTALLIZATION IN AQUEOUS-MEDIA

Hitherto, most discussions of nucleation phenomena have been concerned with the condensation of vapors. In this paper, thermodynamic argumen ts are presented to show that such classical nucleation models are ina dequate for interpreting nucleation in aqueous media The use of the Yo ung equation involving force balance solutions is applicable only for uncharged interfacial systems. To avoid the involvement of a contact a ngle concept, which provides little kinetic information about heteroge neous nucleation, the present paper is concerned with the use of inter facial measurements to calculate the rates of these reactions. The met hod is illustrated by calculation of a rate of heterogeneous nucleatio n of hydroxyapatite at elastin surfaces (4.4 x 10(-8) mol min(-1) m(-2 )) that is close to the value, 3.9 x 10(-8) mol min(-1) m(-2), reporte d in the literature. (C) 1996 Academic Press, Inc.