Uniform colloids

Zorbax PSM particles are made from small (80-2000 A), extremely uniform colloidal silica sol beads. In a patented polymerization process, these beads are agglutinated to form spherical particles. The size of the Zorbax PSM particles is controlled by the polymerization process, and the pore size is determined by the size of the silica sol beads. After polymerization, the silica is heated to remove the organic polymer and sinter the particles. The result is a spherical, porous, mechanically stable, pure silica particle that provides excellent chromatographic performance (Pig. 3.1). 

Johnson, J.E. Matijevic, E. (1992) Interactions of proteins with uniform colloidal hematite and chromium hydroxide particles. II. Stability and mobility. Colloid Polymer Sd. 270 364-369... 

Kraemer, S.M. Hering, J.G. (1997) Influence of solution saturation state on the kinetics of ligand-controlled dissolution of oxide phases. Geochim. Cosmochim. Acta 61 2855-2866 Kraemer, S.M., Xu, J., Raymond, K.N. Spo-sito, G. (2002) Adsorption of Pb(II) and Eu(III) by oxide minerals in the presence of natural and synthetic hydroxamate sidero-phores. Environ. Sd. Technol. 36 1287-1291 Kraemer, S.M. Cheah, S.-F. Zapf, R. Xu, J. Raymond, KN. Sposito, G. (1999) Effect of hydroxamate siderophores on Fe release and Pb(II) adsorption by goefhite. Geochim. Cosmochim. Acta 63 3003—3008 Kratohvil, S. Matijevic, E. (1987) Preparation and properties of coated uniform colloidal partides. I. Aluminum (hydrous) oxide on hematite, diromia, and titania. Adv Ceram. Mater. 2 798-803... 

Maruthe,V.R. Trautwein, A. (1983) Calculation of charge density, electric field gradient and internal magnetic field using molecular orbital cluster theory. In Thosar, B.V. (ed.) Advances in Mossbauer spectroscopy. Elsevier, Amsterdam, 398-449 Matijevic, E. Cimas S. (1987) Formation of uniform colloidal iron(lll) oxides in ethylene... 

Regazzoni, A.E. Matijevic, F. (1983) Formation of uniform colloidal mixed cobalt nickel ferrite particles. Colloids Surfaces 6 189—... 

Despite the fact that the hydrolysis of the ferric ion is exceedingly sensitive to various experimental parameters (temperature, pH, etc.), hematite (a-Fe203) and akageneite ((3-FeOOH) were apparently the first reasonably uniform colloidal metal (hydrous) oxides dispersions reported in the literature, as already indicated in the introduction. Since then, this family of compounds has been the most extensively investigated, with specific emphases on particle uniformity, composition, and morphology. 

These generators, and some others described in the literature, such as the Berglund apparatus (40), result in droplets of a rather narrow size distribution (31,32,39,41), but their major difficulty is in the extremely low quantities of products. While these designs are most useful in establishing the optimum conditions for the preparation of uniform colloids, they are impractical for mass production. To achieve... 

Woods,M.E., Krieger,I.M. Rheological studies on dispersions of uniform colloidal spheres. I. Aqueous dispersions in steady shear flow. J. Colloid Sci. 34,91-99 (1970). 

In the original solventless (or nonsolvent) method, patented in 1889 by Lundholm St Sayers, the soluble NC NG were stirred in hot water by means of compressed air. The dough thus produced was passed betw two rolls heated to 50-60°, whereby the bulk of water was pressed out and the NC-NG gel made into a sheet. This was folded over and passed thru the hot rolls again, and the opn was repeated until the material was converted into a uniform colloid, and all the water removed by evaporation. The sheet was then cut into square flakes, generally coated with graphite, and these were blended with flakes obtained from other sheets... 

Choi, G. R. and Krieger, 1. M. 1986. Rheological studies on sterically stabilized model dispersions of uniform colloidal spheres II. Steady-shear viscosity. J. Colloid Interface Sci. 113 101-113. 

Garg, A. and Matijevic, E. (1988) Preparation and properties of coated uniform colloidal particles. II. Chromium hydrous oxide on hematite. Langmuir 4 38-44. 

Methods of filler pretreatment preparation of a very uniform colloidal suspension of filler especially for chemical synthesis of nanocomposites the quality of the suspension determines the particle size of primary particles, the thickness of the coating and the uniformity of the material... 

Sprycha, R. and Matijevic, E., Electrokinetics of uniform colloidal dispersions of chromium hydroxide, Langmuir, 5,479, 1989. 

Perez-Maqueda, L.A. and Matijevic, E., Preparation of uniform colloidal particles of salts of tungstophosphoric acid, Chem. Mater, 10, 1430, 1998. 

Matijevifi, E., Uniform colloidal barium ferrite particles, J. Colloid Interfac. ScL, 117, 593 (1987). 

Fan, X. Matijevic, E. (1988). Preparation of uniform colloidal strontium ferrite particles. Journal of the American Ceramic Society, 71, C-60-2. 

E. Matijevic Uniform Colloid Dispersions — Achievements and Challenges. Langmuir, 10, 8-16 (1994). 

Y.-S. Her, E. Matijevic, and M.C. Chon Preparation of Well Defined Colloidal Barium Titanate Crystals by the Controlled Double Jet Precipitation. J. Mater. Res., 10, 3106-3114 (1995). Controlled Double-Jet Precipitation of Uniform Colloidal CiystalUne Sr-and Zr-Doped Barium Titanates. J. Mater. Res., 11, 3121-3127 (1996). 

Li Y, Deng Y, Tong X, Wang X. 2006. Formation of photoresponsive uniform colloidal spheres from an amphiphilic azobenzene containing random copolymer. Macromole... 

In the water addition process, the water-adding rate shows a critical influence on the colloid formation. The slow addition rate is necessary to obtain uniform colloids. In a broad water-dropping rate, the sizes of the colloids obtained at the final stage are almost the same. However, when the water-dropping rate is extremely slow, the colloid size will abruptly increase as the dropping rate further decreases and even the aggregates will precipitate from the suspension. 

Figure 5.8 shows some typical TEM images of the colloids, which were obtained from the stable dispersions of PEAPE (Fig. 5.8a), BP-AZ-CA (Fig. 5.8b), and PEAPE/BP-AZ-CA (1 1, wt wt) colloids (Fig. 5.8c). It can be seen from the images that all three systems can produce uniform colloidal spheres. The hybrid colloidal spheres seem to possess a more uniform shape compared with the monocomponent colloids. The DLS measurements were used to characterize the size of colloids in the stable suspensions of the colloids. For the colloids of PEAPE, BP-AZ-CA, and PEAPE/BP-AZ-CA (1 1, wt wt), the average hydrodynamic radii (i h) are 154, 102, and 111 nm. The hybrid colloids show an obviously lower polydispersity (0.061) compared with both the PEAPE colloids (0.138) and the BP-AZ-CA colloids (0.156). UV-vis spectroscopic study on the PEAPE/BP-AZ-CA colloid suspension shows characteristics of both types of azo...

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