Monodisperse polystyrene latex

The adsorption of fully and partially hydrolyzed (88%) polyvinyl alcohol (PVA) on 190-1lOOnm monodisperse polystyrene latex particles was investigated. The effect of molecular weight was investigated for 190 nm-size particles using the serum replacement adsorption and desorption methods. The adsorption density at the adsorption-isotherm plateau followed the relationships for the fully hydrolyzed... 

Ali, S. A. Sengupta, M. J., Preparation and characterization of monodisperse polystyrene latexes of varying particle sizes without the use of surfactants, Polym. Mater. Sci. Eng. 1991, 8, 243 250... 

Calibration of these single-particle counters is usually carried out using monodisperse polystyrene latex or polyvinyl latex spheres, which are available in sizes from 0.1 to 3 /im and have a refractive index of 1.6 alternatively, aerosols with lower refractive indices may be generated from liquids such as dioctyl phthalate (m = 1.49). Whitby and Willeke (1979) discuss the... 

High molecular weight monodisperse polystyrene latexes have been prepared by this method [158]. A number of factors were found to influence the size and dispersity of the particles. The size decreased with increasing surfactant concentration and decreasing internal phase volume, and a more monodisperse latex... 

FIG. 1.8 Electron micrograph of cross-linked monodisperse polystyrene latex particles. The latex is a commercial product (d = 0.500 jun) sold as a calibration standard. (Photograph courtesy of R. S. Daniel and L. X. Oakford, California State Polytechnic University, Pomona, CA.)... 

Monodisperse Polystyrene Latexes Surface Charge and Number of Sulfate Endgroups/Polymer Molecule (3,5,9)... 

Monodisperse Polystyrene Latex A-2 Oxidation of Sulfate and Hydroxyl Endgroups 10 5n silver nitrate 6 hours at 90°)... 

Earlier work (3) has shown that cleaned monodisperse polystyrene latexes stabilized with surface sulfate (and perhaps a few hydroxyl) groups an be used as model colloids. For example, the distribution of H ions in the electric double layer as determined by conductometric titration has been correlated with the particle diameter determined by ultracentrifugation (3). The conductometric titration gives two measures of the concentration of H+ ions the initial conductance of the latex and the amount of base required for neutralization. The number of H+ ions determined by conductance is always smaller than the number determined by titration. This difference is attributed to the distribution of the H+ ions in the electric double layer those closest to the particle surface contribute least to the overall conductance. This distribution is expressed as the apparent degree of dissociation a, which is defined as the ratio H+ ions... 

Thus the monodisperse polystyrene latex stabilized with strong-acid surface groups can be hydrolyzed to form a latex stabilized with the same number of nonionic hydroxyl groups, which in turn can be oxidized to form a latex stabilized with the same number of weak-acid carboxyl groups, thus offering model colloids with identical characteristics except for the type of chemically bound surface groups ---- strong-acid, weak-acid, non-... 

The foregoing methods developed for the preparation and characterization of monodisperse polystyrene latexes to be used as model colloids can also be applied to the characterization of industrial latexes. The recipes used for the preparation of these industrial latexes are complex, and most contain a small amount of a functional monomer, e.g., acrylic acid, 2-sulfoethyl methacrylate, or N-methylolacrylamide. These functional monomers are often predominantly water-soluble, so that their use may have several results (i) the monomer may polymerize in the aqueous phase to form a water-soluble polymer that remains in the serum ... 

For a brief history of the early preparation of monodisperse polystyrene latexes, see Vanderhoff, J.W., Preprints, A.C.S. Division Org. Coatings Plastics Chem., 1964, 2A 9 (2), 223. 

The analysis method employed is the patented external gradient method described in detail elsewhere (1,4). The overall instrument performance was evaluated using monodisperse polystyrene latex standards, covering a range from 0.176 urn to 1.09 pm, obtained from Dow Diagnostics, Indianapolis, Indiana. 

Narrow particle fractions approaching a monodisperse distribution are particularly easy to treat and characterize when the above equations are applied to experimental data. Figure 2 shows an example of the elution profile (fractogram) obtained by running a mixture of four samples of "monodisperse" polystyrene latex beads. It is clear from the figure that a rather precise value of retention volume Vr can be identified with each bead size. With Vr known, it is easy to obtain R and X from Equation 5 and thence particle diameter d from Equation 4. This operation, as noted, yields diameters accurate to approximately 1-3%. 

Monodisperse polystyrene (latex) spheres having a radius value in the range 30-100 run with a standard deviation of 8% or less characterizing the size uniformity. Such samples can be obtained from Duke Scientific Corp. as 3000 Series Nanospheres (www. dukescientific.com), Polymer Laboratories as PL-Latex Plain White (www.polymerlabs. com), and Polysciences, Inc., as Nanobead Traceable Size Standards (www.polysciences. com). 

Figure 10 shows the variation of the relative viscosity with the counterion molarity at different reduced shear stress values for monodisperse polystyrene latex having a diameter of 0.192 xm at dispersed-phase volume fraction = 0.509. Clearly, is a function of the electrolyte concentration in addition to the reduced shear stress. 

Figure 10. Variation of relative viscosity of monodisperse polystyrene latex with electrolyte concentration at different reduced shear stress. (Reproduced with permission from reference 31. Copyright 1972 Elsevier.)...

As model samples for the verification of the conventional SdFFF as a concentration methodology monodisperse polystyrene latex beads (Dow Chemical Co.) with nominal diameters of 0.357 fum (PSl) and 0.481 /Ltm (PS2) were used. They were either used as dispersions containing 10% solids or diluted with the carrier solution (triple-distilled water -r 0.1% (v/v) detergent FL-70 from Fisher Scientific Co. -l- 0.02% (w/w) NaNj) to study sample dilution effects. Diluted samples in which the amount of the polystyrene was held constant (1 /u-L of the 10% solids) while the volume in which it was contained was varied over a 50,000-fold range (from 1 to 50 mL of carrier solution) were introduced into the SdFFF column. During the feeding step, the flow rate was 5.8 mL/h for the PSl polystyrene, and 7.6 mL/h for the polystyrene PS2, and the channel was rotated at 1800 rpm for the PSl sample and at 1400 rpm for the PS2 sample. In the sep-I aration (elution) step, the experimental conditions for the two samples were as follows ... 

DI water, monodispersed polystyrene latex particle and yeast suspension... 

Particle sizes can be controlled precisely in some cases (albeit usually involving trial and error). For example, monodisperse polystyrene latexes suitable as calibration standards can be prepared conveniently by emulsion polymerization. 

Likewise, the polymer latex data of Figure 3.34 have a much higher slope (mass transfer coefficient) than would be expected from the latex particle dif-fusivity. Monodisperse polystyrene latexes have both suspension viscosities and... 

Monodispersed polystyrene latex particles 1.049 pm in diameter (std dev = 0.0587 pm) were captured utilizing a radial flow parallel-plate mobility analyzer (Tardos et. al. 1984). The mobility of the particles was determined from measurements of the collection efficiency of the analyzer by sampling particle number density for the inlet and exit flows (Figure 3-10). The principle was fundamentally that of electrostatic precipitation. The particles were charged by a corona discharge. The particles capture efficiency in the mobility... 

Figure 1.3 Electron micrographs of colloidal materials in which three, two, and one dimensions lie in the colloid range (bars indicate 1/am) (a) spherical particles of monodisperse polystyrene latex, (b) packed spherical particles of polystyrene latex, (c) fibres of chrysotile asbestos, (d) thin plates of kaolinite.

Finally, phospholipidic compounds carrying polymerizable groups such as IX and X have been shown very recently [28] to allow the preparation of stable monodisperse polystyrene latexes, with sizes in the range of 200-300 nm in diameter, carrying a phospholipid layer on their surface with yields higher than 75%. 

Ottewill, R. H. Shaw, J. N. Stability of Monodisperse Polystyrene Latex... 

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