Particle Growth and Nucleation

Eisele, F. L., and P. H. McMurry, Recent Progress in Understanding Particle Nucleation and Growth, Philos. Trans. R. Soc. London, 352, 191-201 (1997). 

Figure 7. Particle nucleation and growth kinetics determined by laser light scattering Rayleigh ratio vs. time. Exp. 1 no surfactant present Exp. 2 (SDS) = 6 X 10 4 mol dm 3. Theor Calculated from Curve 4, Figure 5, considering particle growth by polymerization.

Fig. 6. Schematic model for the particle nucleation and growth of sterically stabilized particles in dispersion polymerization using macromonomer...

Asua and Schoonbrood [49] have produced an extensive review of the literature dealing with copolymerization of Surfmers, of the Surfmers polymerization loci and the influence of Surfmers on particle nucleation and growth. From this, they concluded that the main feature of a Surfmer is its intrinsic reactivity and provided suggestions for the choice of the reactive group in a Surfmer. They also made proposals to maximize Surfmer performance and effectiveness, namely ... 

Macro- and miniemulsion polymerization in a PFR/CSTR train was modeled by Samer and Schork [64]. Since particle nucleation and growth are coupled for macroemulsion polymerization in a CSTR, the number of particles formed in a CSTR only is a fraction of the number of particles generated in a batch reactor. For this reason, their results showed that a PFR upstream of a CSTR has a dramatic effect on the number of particles and the rate of polymerization in the CSTR. In fact, the CSTR was found to produce only 20% of the number of particles generated in a PFR/CSTR train with the same total residence time as the CSTR alone. By contrast, since miniemulsions are dominated by droplet nucleation, the use of a PFR prereactor had a negligible effect on the rate of polymerization in the CSTR. The number of particles generated in the CSTR was 100% of the number of particles generated in a PFR/CSTR train with the same total residence time as the CSTR alone. 

The most successful NQD preparations with respect to nanocrystal quality and monodispersity entail pyrolysis of metal-organic precursors in hot coordinating solvents (120 360 °C). Understood in terms of La Mer and Dinegar s studies of colloidal particle nucleation and growth, these preparative routes involve a temporally discrete nucleation event followed by relatively rapid growth from solution-phase monomers and finally slower growth by Ostwald... 

An interesting development in this field is the recent report by Dameron et al. (88) of the biosynthesis of quantum-sized CdS crystals in the yeast cells Candida glabrata and Schizo saccharomyces pombe. Exposed to Cd ions these cells synthesize certain peptides with an enhanced sulfide production. Small CdS crystals are formed inside the cells. These crystallize in the rock salt structure (and not in the thermodynamically stable hexagonal configuration). The organism controls particle nucleation and growth, so that uniformly sized CdS particles of about 20 A are formed. They show pronounced quantum-size effects. This is the first example of the biosynthesis of quantum-sized semiconductor crystallites. It constitutes a metabolic route for the detoxification of Cd " -infected living cells (see also 89). 

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