Surface defects dewetting

As a film preparation technique, this method has numerous advantages. The adsorption of the polymers is quasithermodynamic, with the chains adsorbing into a local minimum, which makes the films stable against many defects (dewetting, pinhole formation, etc.). Importantly, the technique is not limited to flat surfaces any geometry that can be immersed in solution (or have solution flowed through)... 

Surface tension is not the only property that affects wetting and dewetting. The viscosity of the applied paint also influences wetting and surface defect formation. The rate of wetting is dependent on viscosity as well as surface tension (56). The equation is... 

Silicas are the most widely used active particles in defoamer formulations. Precipitated silicas are used almost exclusively. To be effective, the silica must be reacted with an agent, typically polydimethylsUoxane, to render the surface hydrophobic. The mechanism of bubble breaking is the dewetting of the silica particle by the foam lamella, which creates a defect in the film that leads to its rupture. The criterion for dewetting is a three-phase contact angle of 90° or more (the three phases are the aqueous foam lamella, the silica particle, and the carrier oil in which the particle is dispersed). Patterson has identified the properties of silica that optimize performance in... 

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