Phase Segregation and Enrichment at Surfaces

Perdeuterated poly(methyl methacrylate) is thermodynamically slightly different from poly(methyl methacrylate) This difference in surface energy which is 

Polymer Mn by GPCP Functionality Surface tension (mN m ) Surface fraction of end groups 

It has been shown, however, that provided the gap between the dielectric and another substrate is small, essentially the same EHD instabilities are observed. The equation of motion for the lateral flow of a liquid in a thin film assuming that the fluid is incompressible has the form 

The first term is the disjoining pressure in the film with A the Hamaker constant describing the van der Waals interaction of the film with the surrounding media. The second term represents the electrostatic pressure exerted on the film by an electrostatic potential difference, U, between the conducting media cladding the film, with s being the dielectric constant of the film material. Finally the third term describes the Laplace pressure in the film with cr donating the interface tension between the film and the upper (liquid) medium. 

The liquid will be in thermal motion and there will be a small fluctuation in the thickness in an initially homogeneous film of thickness ho. 

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