van der Waals forces

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van der Waals forc·es

(von der vahls),

first postulated by van der Waals in 1873 to explain deviations from ideal gas behavior seen in real gases; the attractive forces between atoms or molecules other than electrostatic (ionic), covalent (sharing of electrons), or hydrogen bonding (sharing a proton); generally ascribed to dipolar and dispersion effects, π-electrons, and the like; these relatively nondescript forces contribute to the mutual attraction of organic molecules.

van der Waals forces

[van′ der wäls′, fän-]

Etymology: Johannes D. van der Waals, Dutch physicist and Nobel laureate, 1837-1923

weak attractive forces between neutral atoms and molecules. They occur because a fluctuating dipole moment in one molecule induces a dipole moment in another and the two dipole moments interact in an attractive manner. The activity accounts for some deviation from Boyle's law at very low temperatures or very high pressures. Also called dispersion forces.

van der Waals forc·es

(vahn der valz fōrs'ĕz)

Attractions first postulated by J.D. van der Waals in 1873 to explain deviations from ideal gas behavior seen in real gases; the attractive forces between atoms or molecules other than electrostatic (ionic), covalent (sharing of electrons), or hydrogen bonding (sharing a proton); generally ascribed to dipolar and dispersion effects, π-electrons, and other factors; these relatively nondescript forces contribute to the mutual attraction of organic molecules.

van der Waals forces

Weak attractions between non-polar parts of molecules. (Johannes D. van der Waals, Dutch physicist and Nobel laureate, 1837–1923).

van der Waals,

Johannes D., Dutch physicist and Nobel laureate, 1837-1923.

van der Waals forces - explains deviations from ideal gas behavior seen in real gases. Synonym(s): London forces

Van der Waals forces

the relatively weak, short-range forces of attraction existing between atoms and molecules, which results in the attraction of nonpolar organic compounds to each other (hydrophobic bonding).

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References in periodicals archive ?

Elastic moduli of multi-walled carbon nanotubes and the effect of van der Waals forces.

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Although ionic forces make the major contribution to the total energy, after a separation of 6-8 [Angstrom], the van der Waals forces dominate and are most effective at large separations.

Estimation of stresses required for exfoliation of clay particles in polymer nanocomposites

From the values shown in Table 7 it is evident that boiling points of cyclic hydrocarbons increase with the number of carbons z in the molecule non-linearly, divergently, similarly to van der Waals forces and, consequently, relative retention times.

Possibilities of cyclization of side alkyl chains of n-alkylphenols and n-alkylbenzenes in the environment of a stationary phase

The fitting of the experimental force data was done using a theoretical model combining both electrostatic and van der Waals forces for a conical tip-flat substrate system, and this fitting allowed the determination of the surface charge density of the bitumen-water interface.

Determining surface potential of the bitumen-water interface at nanoscale resolution using atomic force microscopy

It demands the appreciation of a ground-up approach to design and problem-solving, and full acknowledgment of the importance of nano-phenomena that run from van der Waals forces to the collision of phonons with grain boundaries.

MEMS from the nanoscale up: before microsystems can fulfill their promise, engineers have to understand that the macroscale rules don't necessarily apply

Unfortunately, says Dhinojwala, the plastic rods "are not mechanically strong, and they try to clump together" He attributes the carbon nanotubes' extraordinary adhesion to both van der Waals forces and to their strength and flexibility under strain.

Nanotube carpet mimics gecko feet

The layers of talc were bonded by weak van der Waals forces and hence talc readily undergoes cleavage to form high aspect ratio particles, which can significantly improve stiffness of polymers.

Intercalation and exfoliation of talc by solid-state shear compounding ([S.sup.3]C) using pan-mill equipment

The single layer of graphene was so thin that it did not significantly disrupt the non-bonding van der Waals forces that control the interaction of water with the solid surface.

'Thin' graphene's completely 'invisible' to water

This mock dirt counteracted the weak van der Waals forces that usually sum into a lizard's tenacious grip on surfaces.

Twinkle toes: how geckos' sticky feet stay clean

Instead, the ideal AFM tip should be made from a multi-wall bundle, he said, one that is stepped down and held together by van der Waals forces.

HYBRID NEMS

2] groups of other chains by van der Waals forces, which were assumed to act at an angle [Phi].

Fractographic evidence

Commercially developed by Park Scientific Instruments, Sunnyvale, CA, the non-contact--or attractive-mode--SFM technique uses the long-range van der Waals forces between the tip and the sample to map the surface's topography.

Conventional SFM tip deforms surface of polyethylene sample ... while non-contact technique gives sharper image