Interactions between Hydrophobized Solid Surfaces in Nonpolar Liquids

3 Interactions between Hydrophobized Solid Surfaces in Nonpolar Liquids 

The cohesion between the hydrophobic part of the interfacial adsorption layer and the adjacent nonpolar phase can be modeled nsing the cohesion between model hydrophobic snrfaces in the same liqnid. In snch a simnlation, the hydrophobic solid snrfaces represent the hydrophobic tails of the snrfactant molecnles. This approach allows one to overcome the difficnlties associated with the mutual solubility of the components (see Chapter 1). For the solid/liqnid/solid interface, the main parameter characterizing the interactions is the free energy of interaction, F (or Aoj), which can be established experimentally nsing Derjagnin s theorem, that is, p = %RF, where p is the cohesive force in a direct contact between two spherical particles immersed in a liqnid medinm. Snitable model systems include spherical molecularly smooth glass beads with a radius R 1-1.5 mm and hydrophobized surfaces of different natures, namely, HS and HL, immersed into the hydrocarbon and fluorocarbon liquids, HL and FL. Only dispersion forces are present in such systems, which makes the quantitative description of their interaction well defined and not complicated by the presence of various polar components. 

Free Energy of Interaction F/2 (i.e., A Tf/2), Work of Adhesion, W, and Interfacial Free 

Energy, ffsLr of Solid Hydrocarbon Surfaces Immersed in Various Nonpolar Liquids  

Note The symbols without a subscript are actual experimental data [34,43]. The data marked with (A) and (F) represent interfacial free energies calculated using Antonow s and Fowkes approximations [59]. The data obtained from contact angle measurements are marked with 

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