Charged repulsion barrier

The charge on a droplet surface produces a repulsive barrier to coalescence into the London-van der Waals primary attractive minimum (see Section VI-4). If the droplet size is appropriate, a secondary minimum exists outside the repulsive barrier as illustrated by DLVO calculations shown in Fig. XIV-6 (see also Refs. 36-38). Here the influence of pH on the repulsive barrier between n-hexadecane drops is shown in Fig. XIV-6a, while the secondary minimum is enlarged in Fig. XIV-6b [39]. The inset to the figures contains t,. the coalescence time. Emulsion particles may flocculate into the secondary minimum without further coalescence. 

In the case of insertion toward fluorine (41), there is an even greater amount of positive-positive charge repulsion between the ortho and ipso carbons than in the transition state and this effect is responsible, in part, for a higher activation barrier for insertion toward F to form 41 than away from fluorine to form 40. Therefore, the origin of the pronounced influence of ortho,ortho-difluoro substitution on the lifetime of singlet arylnitrene and the increased activation energy of its cyclization is the result of combination of the steric effect and the extraordinary electronegativity of fluorine atom. 

Fig. 19. Catalytic effect of neutral salt on the alkaline hydrolysis of monocetyl succinate ions, Ci6H330-C0-CH2-CH2-CO2 . The monolayer bears a net negative electrical charge. This repels the similarly charged hydrolytic hydroxyl ions. The height of this electrical repulsive barrier is reduced greatly by any neutral salts (Davies and Rideal, 21).

Van der Waals forces Surface energy Charge repulsion Steric barriers... 

The stochastic Eden-like model of aggregation of the charged particles in 2D systems was developed [105, 106]. In this model, the particles overcome the electrostatic repulsive barrier created by the aggregate and stick to it due to the existence of short-range attractions. 

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