Diameter Of Latex Particles Research Articles

Effects of diffusion limitation on binding of soluble ligand to avidin-coupled latex particles

The influence of particle diameter on the diffusion limitation of the interaction between a soluble ligand and its specific binder immobilized onto the surface of those particles was investigated in this study. To model a system experimentally, egg white avidin covalently immobilized onto three different diameter latex particles (0.31, 0.65, and 1.25 μm) and soluble biotin-horseradish peroxidase were used. After determination of affinity constants ( K) and the number of binding sites ( B 0) for each particle size to establish initial conditions, the relative diffusion limitation in each case was investigated by measuring the deviation of the reaction kinetics from the relationship ln ([A] M[B] ) = [A 0] – [B 0]) ft . The results were then compared to a mathematical model of the same binding reaction under completely homogeneous, soluble conditions. Larger particle size resulted in a greater deviation of the reaction kinetics from linearity. The extent of diffusion limitation however, was not found to be directly proportional to diameter. The variability in number of binding sites for each of the particle sizes did not bear on these conclusions.

Diffusion-induced banding of colloid particles via diffusiophoresis: 2. Non-electrolytes

We have extended the stopped-flow diffusion cell (SFDC) technique (Staffeld, P. O., and Quinn, J. A., J. Colloid Interface Sci. 130, 69 (1989) to measurements of nonelectrolyte diffusiophoresis using 1-μm diameter latex particles in gradients of Dextran and Percoll. Dextran, a slightly branched nonionic polymer, and Percoll, a negatively charged polymer coated silica particle, interact with latex via steric exclusion at the latex surface. Anderson and Prieve's theory of nonelectrolyte diffusiophoresis is used to interpret the experimental measurements. Interaction parameters determined from our measurements are physically realistic and consistent with theoretical predictions.

Elementary reactions of the emulsions polymerization of styrene with the localization of radical formation acts at the interface

AbstractThe localization of radical formation acts at the interface achieved by the application of specially prepared surfactant initiators, fixation of initiating sites on the surface of seed latex particles by covalent bonds, or by redox initiating systems were experimentally studies. It is ascertained that the fixation of the initiator of polymerization at the interface of the emulsion system brings about a change of the kinetic parameters of its decomposition—an increase in the decomposition rate and decrease in the initiation efficiency. The experiments (measurements of chain propagation rate) demonstrated that the nature of emulsifying agent and initiator has no effect on the chain propagation acts. The kinetics of the chain termination depends on the properties of the emulsion system that is revealed in the dependence of chain termination constants on the type of initiator and the diameter of latex particles. These effects are supposed to be explained by influence of the colloid and chemical parameters of the reaction system on the conformation entropy of the growing macroradicals; and the low values of the chain termination constants (102–104 L mol−1 s−1) are due to the higher activation energy of chain termination for the emulsion polymerization.

Surface sealing of microvoid latex paints by exclusion of small diameter latex particles

On a pu ameliorer la resistance au frottement humide de peintures a microvides en utilisant un mecanisme d'exclusion des petites particules de latex. On a pu diminuer de plus de 50% la quantite de TiO 2 dans une peinture emulsion blanche mate pour interieur sans perte du pouvoir couvrant et avec une resistance au frottement humide satisfaisante

Kinetics of emulsion polymerization of styrene—simulation model with varying free radical capture efficiency

AbstractA kinetic model has been developed and successfully applied to describe the reaction profiles of the seeded emulsion polymerization of styrene. The model incorporated a mechanism for the capture of aqueous‐phase oligomeric free radicals by latex particles. Both the collision and diffusion mechanism were considered. The experimental data agreed well with the collision mechanism. The rate of the free radical capture by latex particles is proportional to latex particle surface area (D2p), and also is a strong function of the rate of free radical generation per latex particle. The model predicts that the rate of polymerization is dependent on the latex particle diameter to the 2.5 power in the gel region. This was demonstrated experimentally by J. W. Vanderhoff et al. (J. Polym. Sci., 20, 225 (1956)). Propagation and termination rate constants for styrene in the 70–90°C temperature range were also determined.

Direct measurement of the translational diffusion coefficients of aggregated polystyrene latex particles

The translational diffusion coefficients of single spheres, and aggregates of polystyrene latex spheres have been measured. The measurements were made using an apparatus constructed for the direct microscopic examination of colloidal particles. A time-lapse method was developed using a pin registered cinematographic camera and the method was tested using spherical polystyrene particles with diameters of 2.00 and 3.47 μm. The movements of linear- and clustered-type aggregates of the smaller diameter latex particles were observed for aggregates containing up to six primary particles. The diffusion coefficients were calculated from the movement of the common centre of mass of each aggregate and evidence was obtained to show that linear, chain-like aggregates are more mobile than cluster-type aggregates containing the same number of primary particles.

Direct measurement of the translational diffusion coefficients of aggregated polystyrene latex particles

The translational diffusion coefficients of single spheres, and aggregates of polystyrene latex spheres have been measured. The measurements were made using an apparatus constructed for the direct microscopic examination of colloidal particles. A time-lapse method was developed using a pin registered cinematographic camera and the method was tested using spherical polystyrene particles with diameters of 2.00 and 3.47 μm. The movements of linear- and clustered-type aggregates of the smaller diameter latex particles were observed for aggregates containing up to six primary particles. The diffusion coefficients were calculated from the movement of the common centre of mass of each aggregate and evidence was obtained to show that linear, chain-like aggregates are more mobile than cluster-type aggregates containing the same number of primary particles.

Particle size dispersion during latex growth

AbstractThe evolution of the latex particle diameter distribution during batch emulsion polymerization is investigated, with emphasis on changes in the breadth of the size distribution. A model utilizing a surface area‐dependent volumetric growth rate of a single particle results in a time‐invariant standard deviation of the size distribution during periods of particle growth only. This behavior is reconciled with some experimental observations by considering the occurrence of particle nucleation during some part of the growth interval. Conclusions based on the results of the model suggest that higher inhibitor and low emulsifier concentrations favor narrow particle size distributions.

Deposition of particles on a cylindrical collector

We have studied the deposition of latex particles of diameter 0.8, 2.8, 5.7, 9.5, and 25.7 μm on a cylindrical collector of diameter 250 μm. Experiments were performed with a horizontal and a vertical cylinder. The position of the particles deposited on the horizontal collector shows the contributions of the various transport mechanisms in a qualitative way. From the deposition rate on the vertical collector the collector efficiency is calculated. The results are compared with existing theories. The data deviate considerably from predictions of the classical interception theory, but agree well with the theory of particle capture including London-van der Waals and viscous forces.

Temporal movement of digestive vacuoles in fedTetrahymena pyriformis GL-9

Studies using cells ofTetrahymena pyriformis GL-9 (which had been grown in and maintained in proteose-peptone/yeast extract medium and then presented first with 0.48 μm diameter latex particles for 70 minutes and then with excess carmine particles, or with the particles added in reverse sequence) have shown that there is temporal sequencing in the movement of digestive vacuoles. Under the conditions employed the digestive vacuoles are egested from the cells in approximately the order in which they were formed.

Hindered diffusion of particles through small pores

The diffusion coefficient of 910 Å diameter latex particles was measured as a function of pore radius and solution ionic strength. Membranes with uni

Improvement of the determination of latex particles diameter with application to emulsion polymerization studies

AbstractThe combination of modern techniques allows to make a quick exploitation of electron micrographs for the determination of particles diameter in emulsion polymerization studies. This new method is based on the automatic recording of the particles diameter on the negative films. An application is given for polyvinylchloride latexes. Since the method allows to deal with very large samples of emulsion particles. the best uses are calibration of other methods and particular studies in polymerization. As an example, the specific surface of a molecule of sodium lauryl sulfate adsorbed on PVC is determined to be 58.3Å2.

Filtration of aqueous latex suspensions through beds of glass spheres

Initial (clean bed) latex suspension collection has been measured in filtration through beds of packed glass beads with systematic variation of monodisperse latex particle diameter (0.7–21.0 μm), glass bead diameter (0.1–4.0 mm), flow rate (0.01–1.0 cm/sec), and ionic concentration (10 −1 to 10 −5.5 M) of aqueous medium electrolyte [HNO 3, NaCl and Ca(NO 3) 2]. The use of a Coulter counting system and bed depths ranging from a few to several hundred centimeters permitted measurement of filter coefficients over a factor of 50,000. Double layer repulsion was evaluated using zeta potentials measured by conventional electrophoresis and streaming potential techniques. When double layer repulsion is unimportant, the dimensionless filter coefficient is correlated by a dimensionless adhesion and gravity group as implied by theory. Collection data are also compared to the theory for collection by combined interception and gravity, which is found to give much poorer agreement. Selected data of other workers are compared to theory separately.

The effect of refractive index of the mounting medium on the apparent diameter of latex particles and glass fibres.

SUMMARYThe diameters of latex particles were measured in different media with a light microscope. The microscope was fitted with a filar micrometer eyepiece and, for measurement, the cross‐wire was set on the centre of the dark line forming the edge of the image. Electron microscopy was used for comparison. Good agreement between light and electron microscopy was obtained using media of relative refractive index (nd object/nd medium) between 1·06 and 1·08. With higher relative refractive indices the light microscope underestimates dimensions for particles 4·17 μ diameter and overestimates for particles 2·7 μ diameter.