Hamaker constant and effective attraction

In summary, the effective attraction between two identical bodies immersed in a liquid is increased due to the liquid molecules acting as a bridge between them, resulting in attractive forces between the bodies. This causes the effective Hamaker constant to be larger than in a vacuum.
  • #1
kyraz
1
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Hello,

According to the following equation describing the effective Hamaker constant of two identical bodies immersed in a liquid : AALA = (AA1/2 - AL1/2)2, for high values of AL, the effective attraction of the A-like media is larger than in vacuum. How is this possible physically ?
 
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  • #2
The increase in attraction between two identical bodies immersed in a liquid is due to the molecules of the liquid acting as a bridge between them. The liquid molecules interact with the molecules of both bodies, creating attractive forces between them. This increases the effective attraction of the two bodies over what it would be in a vacuum.
 

1. What is the Hamaker constant?

The Hamaker constant is a physical constant that describes the strength of the van der Waals forces between two objects. It is named after Dutch physicist Hendrik Casimir and Russian physicist Abram Ioffe, who first proposed its existence in the 1930s.

2. How is the Hamaker constant calculated?

The Hamaker constant is calculated using the Lifshitz theory, which takes into account the polarizability of the materials and the distance between them. It can also be experimentally measured using techniques such as atomic force microscopy.

3. What is effective attraction?

Effective attraction refers to the total attractive force between two objects, taking into account all types of intermolecular forces including van der Waals forces, electrostatic forces, and hydrogen bonding. The Hamaker constant is one factor that contributes to the effective attraction between two objects.

4. How does the Hamaker constant affect adhesion?

The Hamaker constant plays a significant role in determining the strength of adhesion between two surfaces. A higher Hamaker constant indicates a stronger attraction and thus a stronger adhesion force. This is important in various applications such as adhesives, coatings, and surface treatments.

5. Can the Hamaker constant be modified?

Yes, the Hamaker constant can be modified by changing the surface properties of the materials involved. For example, the Hamaker constant can be increased by adding polar functional groups to the surface, or decreased by introducing repulsive forces through surface modifications. These modifications can be used to control the adhesion properties of materials.

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