please give some details and recommend a ref to understand the detailed mechanisms.?
dewetting is the process by which a fluid moves to uncover a substrate. It can begin in several different ways, for example spinodal dewetting or nucleation and growth. Nucleation and growth refers to the random nucleation of holes in the film (i.e. the substrate has been revealed to the air), one might say this is rupture (the film has been ruptured once a hole opens up).
Spinodal refers to the growth of a fluctuation in thickness, so may not reveal the substrate for some time. The film is dewetting, but it has not been ruptured. This will only occur in very thin films though, so I think you are probably interested in the nucleation regime.
Once a hole has formed, dewetting proceeds by slowly enlarging the hole. Again there are different dynamics depending on the boundary conditions, driving forces, and properties of the fluid layer.
The final stage of dewetting involves the coalescence of many holes, ultimately leaving a pattern of droplets on your substrate.
In thermodynamics the wetting phenomenon of a droplet on a substrate may be defined by the following connection If [(GamaS - GamaSF) - GamaF Cos Theta] > 0 There will be wetting of the droplet over the substrate surface. Otherwise no wetting takes place. This may be also represented by the following formula:
GamaF [Lambda- Cos Theta] => 0, Where Lambda is the wetting parameter, which is defined by: Lambda=GamaS - GamaSF)/GamaF where { 0< Lambda < 1} for wetting and Similarly dihedral angle, which is the angle between the droplet tangent vector at the triple junction, may be defined by: Theta = arcos ( Lambda) EQL 180o Implies wetting zero is the complete wetting. Otherwise there is dewetting typical case mercury of the substrate.
GamaS is surface Free energy of the Substrate; GamaF is surface Free energy of the Film;
Gama SF is the interface free energy between the film and the substrate.
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