Explaining the low-frequency shear elasticity of confined liquids

Structure of confined alkane liquids

Alkane and polymer fluids near surfaces and in confined geometries arepresently of intense interest but poorly understood.‘” Direct experimental probing of confined liquid structure is difficult and indirect due to the small amount of material present. Computer simulations on coarse-grained’ and atomistic’ model chain molecule fluids have provided considerable insight, but are expensive and lim...

Problems Associated with the Elasticity of Liquids

Properties of Water Confined in Ionic Liquids

The varying states of water confined in the nano-domain structures of typical room temperature ionic liquids (ILs) were investigated by (1)H NMR and by measurements of self-diffusion coefficients while systematically varying the IL cations and anions. The NMR peaks for water in BF4-based ILs were clearly split, indicating the presence of two discrete states of confined water (H2O and HOD). Prot...

Dynamics of layering transitions in confined liquids.

Multiple beam interferometry and video microscopy were used to investigate the layering transition of thin liquid films of 1-undecanol confined between atomically smooth mica surfaces. The expulsion of a molecularly thin lubricant layer was followed directly in two dimensions. Overall, the dynamics of the transition follows theoretical predictions based on two-dimensional hydrodynamics. Frequen...

Motions and relaxations of confined liquids.

When a liquid is confined in a narrow gap (as near a cell membrane, in a lubricated contact between solids, or in a porous medium), new dynamic behavior emerges. The effective shear viscosity is enhanced compared to the bulk, relaxation times are prolonged, and nonlinear responses set in at lower shear rates. These effects are more prominent, the thinner the liquid film. They appear to be the m...