Mobility of polystyrene latex

FICU RE 19.2 Profiles of the electrophoretic mobilities of polystyrene latex microspheres in the spinning ceU for various polymers or surface treatments in the presence of a cationic surfactant (10 mM, TTAB) in the immersing liquid. 

Elimelech, M. and C. R. O Melia. 1990. Effect of electrolyte type on the electrophoretic mobility of polystyrene latex colloids. Colloids and Surfaces 44 (C) 165-178. 

On basically hydrocarbon-hydrophobic substrates such as polystyrene, it is well established that even on the negatively charged particles there is adsorption of surfactant anions via the hydrocarbon chains. This is demonstrated in the work of Kayes (1976), who found a substantial increase in the electrophoretic mobility of polystyrene latices with increase in the concentration of dndecyl sulfate in the system, and in the work of Cebula et al. (1978) on the adsorption of dndecanoate ions on polystyrene latex particles. 

Figure 1.13 Stability ratio (a) and electrophoretic mobility (b) of precipitated calcium carbonate (PCC) as a function of polystyrene latex addition, in distilled water (DW) and in tap water (TW).

Polystyrene latexes were similarly prepared by Ruckenstein and Kim [157]. Highly concentrated emulsions of styrene in aqueous solutions of sodium dodecylsulphate, on polymerisation, yielded uncrosslinked polystyrene particles, polyhedral in shape and of relative size monodispersity. Interestingly, Ruckenstein and coworker found that both conversions and molecular weights were higher compared to bulk polymerisation. This was attributed to a gel effect, where the mobility of the growing polymer chains inside the droplets is reduced, due to increased viscosity. Therefore, the termination rate decreases. 

Particle electrophoresis studies have proved to be useful in the investigation of model systems (e.g. silver halide sols and polystyrene latex dispersions) and practical situations (e.g. clay suspensions, water purification, paper-making and detergency) where colloid stability is involved. In estimating the double-layer repulsive forces between particles, it is usually assumed that /rd is the operative potential and that tf/d and (calculated from electrophoretic mobilities) are identical. 

Figure 7.7 Zeta potentials (calculated from electrophoretic mobility data) relating to particles of different ionogenic character plotted as a function of pH in acetate-veronal buffer at constant ionic strength of 0.05 mol dm 3, (a) Hydrocarbon oil droplets, (b) Sulphonated polystyrene latex particles, (c) Arabic acid (carboxylated polymer) adsorbed on to oil droplets, (d) Serum albumin adsorbed on to oil droplets...

Figure 2. Variation of electrophoretic mobility in distilled water with pH for polystyrene latex particles with different surface groups (1) 520 sulfate (2) 520 carboxyl (3) 520 hydroxyl (4) LS-1010-E sulfate (5) LS-1010-E hydroxyl.

The Relationship Between the Electrophoretic Mobility and the Adsorption of Ions on Polystyrene Latex... 

Characterization of the Polystyrene Latex Samples. The polystyrene, PS, latex samples under investigation were characterized according to particle size, concentration of surface sulphates and electrophoretic mobility, em, in deionized water. The results, Table I, show that all the samples were of similar size with the exception that the Dow latexes were monodisperse while... 

FIG. 3 Apparent panicle mobility in 7.5 mM NaCI of a sulfated polystyrene latex particle across the diameter of a closed quart/, cylindrical chamber. Profiles are associated with varying degrees of electro-osmosis at pH 2 (O). pH 6 ( ). and pH 11... 

Table 4.2. Electrokinetic potentials of negative polystyrene latex particles obtained from electro-osmosis, electrophoresis and conductivity. In the conversion of mobilities surface conduction behind the slip plane was ignored. (Data from A.G. van der Put, PhD. thesis. Agricultural University Wagenlngen. NL (1980) as elaborated by O Brlen, J. CoOoid Interface Set 110 (1986) 477.)...

Pellicular anion-exchange sorbents may also consist of quaternized latex hydrophobically coated onto the surface of an unsulfonated polystyrene solid core. However, using hydro-organic mobile phases can easily wash off the latex particles held onto the particle surface by hydrophobic interactions. 

Ma, C.M. et al.. The relationship between the electrophoretic mobility and the adsoiption of ions on polystyrene latex, in Emulsion Polymers and Emulsion Polymerization, Bassett, D.R. and Hamielec, A.E., eds., American Chemical Society, Washington, DC, 1981, p. 251. 

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 9.15 A micrograph of a single NaCl particle with electrical mobility equivalent diameter of 550 nm. The dry NaCl is almost cubic with rounded edges. Also shown is a polystyrene latex (PSL) particle with diameter of 491 nm (Zelenyuk et al. 2006). 

As well as obtaining the ccc it is also useful to measure the electrophoretic mobility of the particles used as a function of concentration of the same electrolyte as used for the stability measurements. The electrophoretic mobility can then be converted into a -potential and a comparison made with the stability ratio measurements as shown in Figure 3.11. These measurements were made on a carboxylate polystyrene latex, with a number-average diameter of 423 nm [41]. The ccc for barium chloride solutions was found to be 1.41 x 10 mol dm and rapid coagulation commenced at a -potential of 17 mV. 

Figure 1. A 0.01 vol% polystyrene latex in 0.01 M KNO3 solution (a) mobility as a function of pH...

The size distributions of colloidal suspensions of nanoparticles 74 nm to 14 nm in diameter are analyzed on-line. The sols are first diluted in water seeded with enough TFA to attain electrical conductivities in the range of 0.01 S/m. The solution is then finely dispersed into an atmosphere of CO2 via a Taylor cone-jet. The resisting electrospray of ultrafine droplets dries, transferring the solution particles virtually uncontaminated into the gas. There they are sized by means of a differential mobility analyzer and an inertial impactor of unusually high resolution. The technique is first tested successfully with previously calibrated monodisperse polystyrene latex (PSL) spheres 74 to 21 nm in diameter. It is then used to size a solution of colloidal silica with particle diameters nominally between 10 and 14 nm. 

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