van der Waals attraction

van der Waals attraction

[′van dər ‚wȯlz ə‚trak·shən]
(physical chemistry)
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Among his topics are the origin of charge at interfaces and structure of the electrical double layer, Van der Waals attraction, the adsorption of surfactants at the liquid/liquid interface, polymers and polymeric surfactants and their association, and the flocculation of sterically stabilized dispersions.
[10.sup.-20] (5), [N.sub.A] = A(12[pi][my][(0.5dp).sup.2]v) (attraction number; combined influence of van der Waals attraction forces and fluid velocity on particle deposition by interception), and NG = ([P.sub.p]--[P.sub.f])[gd.sup.2.sub.p]/18[micron]v (gravity number; ratio of Stokes particle settling velocity to approach velocity of fluid).
They are based on implicit-solvent, computer simulation studies of a model Ti[O.sub.2] dispersion that takes into account three major components to the interaction between colloidal particles, namely van der Waals attraction, repulsion between polymer coating layers, and a hard-core particle repulsion.
According to DLVO theory [1], the molecular forces between particle and wafer surface are mainly the electric double-layer repulsion and van der Waals attraction; other intermolecular forces are smaller than them in the order of magnitude and therefore can be ignored.
Research led by Kellar Autumn at Lewis and Clark College in Portland, Ore., found that the divided points of contact served as a way to increase the van der Waals attraction between the toes and the surface of the gecko is climbing.
It is remarkable that in the fracture surface and behind it, the particles remained in contact during and after freeze-fracture: that is undeniable evidence of van der Waals attraction force and perhaps additional surface forces holding them together, because there is no sign of their being welded by coalescence.
The author has organized the main body of his text in thirteen chapters devoted to the structure of the electrical double layer and the origin of charge at interfaces, electrokinetic phenomena and zeta potential, Van der Waals attraction, and a wide variety of other related subjects.
Polymerization enhanced van der Waals attraction between the phthalocyanine, combined acting together with the disturbance of electronic structure of the phthalocyanine and made changes between the ground state and the excited state, which has a significant influence on the optical properties, catalyst activity, and stability of MPc [12].
The tubes may be drawn to the electrode by an electrical attraction, but they are held there by van der Waals attraction, a sort of molecular-level suction.
Unfortunately, GNPs are easy to agglomerate due to strong interplatelet van der Waals attractions and high surface energy, and hard to disperse in the composite.
Dorbolo and Vandewalle say they've conducted recent experiments that suggest that the antibubbles oppose van der Waals attractions with some counterforce, perhaps electrostatic repulsion, between detergent molecules that protrude into the air gap from the liquid on either side.
Usually, short-range forces originating from molecular forces, such as van der Waals attractions of the particle surfaces (47), are prevalent in dry particles and in polymeric systems.