Anomalous long-range repulsion between silica surfaces induced by density inhomogeneities in supercritical ethanol.

Mukai, Sada-atsu; Koyama, Takehito; Tsujii, Kaoru; Deguchi, Shigeru · Soft Matter · 2014

basic_science · Level V

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Abstract

Anomalous long-range repulsion, extending over several micrometres, emerged between silica surfaces around the ridge of density fluctuations in supercritical ethanol at temperatures and pressures near the gas/liquid critical point (T(c) = 241 °C, P(c) = 6.14 MPa). Analysis shows that augmentation of ethanol density around silica surfaces in the presence of density fluctuations facilitates dissociation of silanol groups, leading to long-range electrostatic repulsion in the nonpolar medium.