Dispersion of a Nonwetting Liquid in a Disordered Nanoporous Medium

A dispersion transition in the Fluka 100 С8 and Fluka 100 С18 hydrophobic silica gels close in the structural characteristics has been studied. Nonlinear dependences of the volume of the trapped liquid on the degree of filling, which have not yet been observed at the interaction of nonwetting liquids with nanoporous media, have been revealed. Two critical temperatures Tc1 ≈ 330 K and Tc2 ≈ 340 K have been found for the Fluka 100 С18/water system. At a temperature above Tc1, a transition occurs at a degree of filling of 0.5 from the state of the system with a linear increase in the volume of the trapped liquid with the degree of filling to the state in which the dispersion transition occurs at a degree of filling of 0.5. At temperatures above Tc2, the fraction of the trapped liquid is small and independent of the temperature and degree of filling. When Fluka 100 С8 is filled with water, no abrupt change in the volume of the trapped liquid with an increase in the degree of filling has been detected in the temperature range under study T = 300–360 K. In this case, a linear increase in the volume of the trapped liquid with the degree of filling has been observed.