High energy solid surfaces

It has been observed the formation of continuous liquids on high-energy solid surfaces, such as mica, quartz, and silica, when those surfaces are subjected to immersion and emersion in water [13,14]. A continuous film of water on a hydrophilic (i.e., high energy) plasma polymer-coated glass slide moments after it was immersed to a depth of 3 cm in a beaker of DDI water is shown in Figure 26.21A. The water film remained continuous as it receded to the bottom of the plate. After about 2 min the water film front receded to approximately 1 cm from the bottom of the plate, as shown in Figure 26.21B. The presence and stability of a continuous water film can be detected and quantified by the Wilhelmy method [15]. 

Solidification on a high-energy solid surface has been observed using a surface force analyzer (SFA) [Israelachvili et al., 1984 Horn and Israelachvili, 1988] and the neutron scattering method [Cosgrove et al., 1987,1991]. The presence of a solidified layer has been predicted by the molecular dynamics (MD) or Monte Carlo (MC) methods [Fleer et al., 1993 Hentschke, 1997 Termonia, 2009]. The information indicates that in the orthogonal (to the clay surface) direction, between the clay surface and the liquid matrix (with bulk properties, i.e., expected molecular mobility at given... 

In the discussion which follows a critical review of the contact angle data will be made emphasizing the hysteresis effects and the measurements on low and high energy solid surfaces. The use of... 

A distinction can be made between low-energy and high-energy solid surfaces. The surface energies of organic compounds, such as polymers, are usually less than 100 mj/m. Metals, metal oxides, and ceramics are typically greater than 500 mj/m ... 

The contact angle is 0ca < 90° when the solid is hydrophilic (so-called high energy solid) and the water wets such a solid well it is usually < 30° and approaches zero when the water completely spreads over the solid. For hydrophobic solids (so-called low energy solids) 0ca > 90° and may have values up to 150° for so-called superhydrophobic surfaces such as specially prepared (non-wettable) fluorohydrocarbons. There exists some hysteresis (amounting typically up to 10°) between the contact... 

High-energy solids such as glass and poly(ethylene terphthalate) have high critical surface tensions (y. > 40 mN m ). Lower energy solids such as polyethylene have lower ( 31 mN m ). TTie same applies to hydrocarbon surfaces such as paraffin wax. Very low energy solids such as PTFE have lower y, of the order of... 

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