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The thermodynamic model of a 2D solution developed earlier for protein monolayers at liquid interfaces is generalized for monolayers composed of micro- and nanoparticles. Surface pressure isotherms of particle monolayers published in the literature for a wide range of particles sizes (between 75 microm and 7.5 nm) are described by the theoretical model with one modification. The calculations of surface pressure pi on area A provide satisfactory agreement with the experimental data. The theory also yields reasonable cross-sectional area values of the solvent molecule water in the range between 0.12 and 0.18 nm2, which is almost independent of particle size. Also, the area per particle in a closely packed monolayer obtained from the theory is quite realistic.

Long-time auto-oscillation of the surface tension can evolve when in an aqueous system a diethyl phthalate droplet is placed under the free water surface. The experimental conditions for development of surface tension auto-oscillations are described. Based on a theoretical analysis the mechanism of these auto-oscillations is proposed. The mechanism of the auto-oscillations results from a switching between diffusion and convection transfer of diethyl phthalate in the solution. A periodic Marangoni flow on the water surface resulting from a surface layer instability is discussed. The solubility of the amphiphile in the water and its surface activity are the main characteristics that determine the system behavior.

The mechanism of the meniscus oscillations and the stripes formation within the deposited fatty acid monolayer is theoretically analyzed on the basis of a supposition of concentration polarization within the solution during the deposition process. The concentration polarization can lead to decrease of adhesion work, dynamic contact angle, and maximum deposition speed under dynamic conditions resulting in meniscus instability. The adhesion work is evaluated from the disjoining pressure isotherm at a given subphase composition taking into account the charge regulation for a fatty acid monolayer. The relation of the proposed mechanism to the known experimental facts and observations is discussed.