Surfactant adsorption compressive force

The droplets formed as a result of the rupture of the liquid column were then again brought into direct contact, became flattened, and eventually coalesced. In the absence of any surface active matter (i.e., in pure water), the droplets of both HL and FL coalesced spontaneously. In this case, the adsorption bilayer needs to be ruptured. In a surfactant solution, a particular compression force must be applied for the droplets to coalesce. Hydrostatic effects were avoided in these experiments because very small volumes of nonpolar phases were used—the ratio of the liquid column length to the base radius, Hr, was between 1.0 and 1.2. 

The drops formed by the split of the column are then brought again into contact. Their flattening and subsequent coalescence are observed. In the absence of any surfactants (in pure water ), the drops of pure HL (or FL) merge spontaneously. In a surfactant solution, it is necessary to apply a definite compressive force oai for the coalescence of HL or FL drops (rupture of a symmetric adsorption bilayer). Hydrostatic effects were avoided by carrying out the experiments with small volumes of nonpolar liquid the ratio I/r of the length of the cylindrical column to its radius is 1.0-1.2. 

Several independent experimental methods were applied that allowed comparison of the properties of these systems [ 18-20]. We present only the principal results of the three foDowing approaches (i) rheological studies of interfacial adsorption layers (lAL) by the rotating suspension method (ii) observation of the compression of two nonpolar droplets in the surfactant aqueous solution, with measurement of the force needed for their coalescence and (iii) evaluation of the free energy of interaction between nonpolar groups of lAL and various nonpolar liquids by measuring the contact rupture force between two methylated (or fluorinated) smooth solid particles in a given liquid. 

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