Adhesion force due to water or surfactant

Water or surfactant may form the bridge between two particles. The adhesive force between two spheres with a water bridge can be expressed as [28J  

A surfactant bridge model which combines the electrostatic force and the surface tension force w as also proposed to explain the surfactant-activated ER effect phenomena 131, 321  

Since this model is based on the point-dipole approximation [33], the limitation is obvious, which will be addressed further in a future chapter. 

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