Verwey-Overbeek theory

The DLVO (Derjaguin-Landau-Verwey-Overbeek) theory describes the stability of a colloidal suspension as mainly dependent on the distance between the particles... 

THE DERJAGUIN-LANDAU-VERWEY-OVERBEEK THEORY OF COLLOID STABILITY... 

What is the Derjaguin-Landau-Verwey-Overbeek theory ... 

The stability of latexes during and after polymerization may be assessed at least qualitatively by the theoretical relationships describing the stability of lyophobic colloids. The Verwey-Overbeek theory (2) combines the electrostatic forces of repulsion between colloidal particles with the London-van der Waals forces of attraction. The electrostatic forces of repulsion arise from the surface charge, e.g., from adsorbed emulsifier ions, surface sulfate endgroups introduced by persulfate initiator, or ionic groups introduced by using functional monomers. These electro-... 

DLVO theory (Derjaguin-Landau-Verwey-Overbeek theory) — The DLVO theory is named after Derjaguin and Landau [i], and Verwey and Overbeek [ii]. It describes the forces acting between colloidal particles in... 

The d vs. c mapping enables us to make a comparison between the coulombic attraction theory and DLVO (Derjaguin-Landau-Verwey-Overbeek) theory over the whole two-phase region. As we saw in Chapter 2, the leading predictions of the two theories are as follows. 

When speculating about the colloidal stability of a monomer droplet dispersion in water, one could use the Deryaguin-Landau-Verwey-Overbeek theory, also known as DLVO theory, to analyze the stability of the system. This has been done in Fig. 10a, where we show the effect of different surface potentials upon the rate of coagulation, fi, defined in the case of two droplets of the same size as ... 

FIGURE 9.5 Comparison between the Deijaguin-Landau theory [9] and the Verwey-Overbeek theory [10]. These two theories give the same result. 

The classical intuition on molecular forces is embodied in the famous Derjaguin-Landau-Verwey-Overbeek theory of colloid stability. It blends themes (i) and (ii) above in a contradictory way that has taken imtil the last few years to sort out. 

In Colloid Science Kruyt, H.R., Ed. Elsevier Amsterdam, 1952 266-270 Schenkel, J.H. Kitchener, J.A. A test of the Derjaguin-Verwey-Overbeek theory with a colloidal suspension. Trans. Faraday Soc. 1960, 56, 161-173. 

Kitchener and coworkers (12, 16) have shown that when colloidal size particles with the same charge sign as that of the planar surface diffuse to and sorb on the latter, the rate of uptake may be considerably less than that predicted by simple Fickian diffusion across the unstirred liquid film, principally because of the double layer repulsive forces, as treated in the Derjagin-Landau-Verwey-Overbeek theory of colloid stability. It was found in some systems, particularly at high ionic strength, that the sorption rate decreased with time, eventually becoming negligible. 

Earlier experimental and theoretical studies of systems in which particles interact through Van der Waal s attraction and electrostatic repulsion led to the development of Derjaguin-Landau-Verwey-Overbeek theory (DLVO). This theory has been successful in providing a quan-... 

Aggregation of liposomes upon storage also depends on membrane components. Liposomes that included taurine as an isotonic solute were most stable at an optimal content of benzalkonium chloride.721 Repulsive energy forces between particles described by the Deryaguin-Verwey-Overbeek theory appeared to account for the stabilization. 

This figure compares with an electrical barrier of 0.28 eV estimated from the point charge model. These values would coincide for a = 0.34. Hence the theory based on the Verwey-Overbeek potential is consistent with experiment. From (4) and (5) the experimental plot of In v versus AF should yield a straight line with the so-called Liley slope. Inserting the numerical values, we find that this slope, with a = 0.34, corresponds to a tenfold increase in frequency of MEPP for each 15.0 mV depolarization. The most recent experimental value on the rat muscle preparation was 12.5 mV, and Liley reported about 16 mV. We can thus conclude that a discussion of the approach of a synaptic vesicle to a presynaptic membrane, which is based on the Verwey-Overbeek theory of the interaction of two double layers, gives reasonable quantitative agreement with the available data on the dependence of V of MEPP on depolarization of the presynaptic membrane. 

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