Cluster Coagulation and Growth Limited by Surface Interactions with Polymers

Abstract

The physical and chemical properties of metal nanoparticles differ significantly from those of free metal atoms as well as from the properties of bulk metals, and therefore, they may be viewed as a transition regime between the two physical states. Within this nanosize regime, there is a wide fluctuation of properties, particularly chemical reactivity, as a function of the size, geometry, and electronic state of the metal nanoparticles. In recent years, great advancements have been made in the attempts to control and manipulate the growth of metal particles to pre-specified dimensions. One of the main synthetic methods utilized in this endeavor, is the capping of the growing clusters with a variety of molecules, e.g. polymers. In this paper we attempt to model such a process and show the relationship between the concentration of the polymer present in the system and the final metal particle size obtained. The theoretical behavior which we obtained is compared with experimental results for the cobalt-polystyrene system.

Distribution Patterns Due to Diffusion in a Coagulation-Fragmentation Process With Cluster-Wall Interactions

“…A combination of both has been proposed by Rotstein et al (1998) to account for changes in the mechanism of coagulation as the cluster size increases. As in Rotstein and Tannenbaum (2002), we recognize the fact that there is a decline in particle mobility through the medium as a function of increased particle size.…”

“…A combination of both has been proposed by Rotstein et al (1998) to account for changes in the mechanism of coagulation as the cluster size increases. As in Rotstein and Tannenbaum (2002), we recognize the fact that there is a decline in particle mobility through the medium as a function of increased particle size. Moreover, the presence of the polystyrene molecules in the reaction solution contributes to the formation of a viscous medium that will impose an upper boundary on the ability of larger clusters to interact via surface-surface interactions, and hence these types of interactions will have a negligible contribution to the overall coagulation process.…”

“…Therefore, the expression that we propose for the coefficients of coagulation of the cobalt fragments in our model (with or without polymer interactions) is (Rotstein and Tannenbaum, 2002) …”

“…We assume that large clusters dissociate preferentially into smaller fragments of similar size rather than into fragments of large size difference. Therefore, the expression that we propose to describe the dissociation of large cobalt clusters into smaller fragments is (Rotstein and Tannenbaum 2002) …”

A Facile Plant Mediated Synthesis of Magnetite Nanoparticles Using Aqueous Leaf Extract of Ficus Hispida L. for Adsorption of Organic Dye

“…Among all magnetic metal oxides, magnetite (Fe 3 O 4 ) have emerged potential candidates for advance technological applications due to their low toxicity, biocompatibility and super paramagnetic behaviour [7][8][9]. Upto now, various morphologies, such as nanorods, nanowires, nanofibers, nanoflowers, nanotubes, nano cage, and nanoparticles have been prepared for Fe 3 O 4 NPs by several chemical and physical approaches such as Co-Precipitation, hydrothermal, thermal decomposition of iron carbonyls, poloyl, electrochemical deposition, spray and laser pyrolysis and sono chemical method [10][11][12][13][14][15][16][17][18][19][20]. In all these methods, synthesis of Fe 3 O 4 NPs uses toxic or potentially hazardious materials and requires more energy.…”