Self-nucleation parameters

The nucleation rate of a polymer is the product of a mass transport and nucleation parameter (Avrami, 1939), where the transport factor is related to a chain s self-diffusion therefore the reduction in crystalline phase and crystallisation temperature could be explained by the coupling of functional carbonyl anhydride molecules with the reactive silanol sites on the silicate... 

These contradictory results about the sequence of calcium phosphate phase nucleation and growth demonstrate vividly how complex and in many important details not yet understood mechanisms appear to govern biomimetic formation of bone-like hydroxyapatite. In particular, the transformation of OCP to HAp was shown to be crystallographically controlled (Fernandez et al., 2003) because hydroxyapatite and octacalcium phosphate can form an epitaxial interface. A new OCP-HA interface model based on an earlier configuration model (Brown, 1962) and using the minimum interface free-energy optimisation was presented. In this new model a structure is formed that consists of half a unit cell of HAp and one unit cell of OCP whereby [0001]HAp is parallel to [001]OCp and [1210]HAp is parallel to [010]Ocp (Figure 7.66). It was shown by self-consistent field methods that the atoms of this model possess similar environments as in the HAp and OCP unit cells and that, as a result of the differences between HAp and OCP unit cell parameters, this interface displays misfit dislocation-like features. 

Parameter Solution-cast plaque Unnucleated moulding Self-seeded moulding Nucleated moulding... 

The preparation of crystalline low-dimensional molecular solids, commonly is performed by electrocrystallization techniques wherein redox active molecules are reduced or oxidized at a working electrode in the presence of appropriate counterions. Very little is known, however, about the effect of electrochemical parameters and interfacial structure on the self assembly processes that lead to crystallization on the electrode surface. This work will describe the electrocrystallization of various crystalline molecular solids, focusing on the control of nucleation, growth, morphology and stoichiometry of these materials through manipulation of the electrochemical growth conditions and interfacial properties of the electrode. 

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