Universal G ∼ L −3 law for the low-frequency shear modulus of confined liquids

Alessio Zaccone , Laurence Noirez (1, 2)

1 LLB - UMR 12 - Laboratoire Léon Brillouin
2 NFMQ - LLB - Nouvelles frontières dans les matériaux quantiques

Microfluidic and nanofluidic technologies have asserted themselves as new paradigms which have radically boomed activities dedicated to the chemical, bio-analysis and biomedical sectors. In spite of intense technological development, the fundamental physico-chemical properties of liquids confined on sub-millimeter scales have remained poorly understood. One of the most striking effects is the large elasticity (and viscosity) of confined liquids, which grows upon further decreasing the confinement length, L. Liquids under sub-millimeter confinement display a low-frequency shear modulus in the order of 1 − 10 3 Pa, contrary to our everyday experience of liquids as bodies with a zero low-frequency shear modulus. While early experimental evidence of this effect (starting with Boris Derjaguin's work) was met with skepticism due to its counterintuitive character and abandoned, further experimental results and most recently a 1 new atomistic theoretical framework have confirmed that liquids indeed possess a finite low-frequency shear modulus G and that this scales with the inverse cubic power of confinement length L. After a brief historical overview and an introduction to the theoretical description of this effect, we show that this law is universal by analyzing experimental data on a wide range of materials (water, glycerol, ionic liquids, nonentangled polymer liquids, isotropic liquids crystals). Open questions and potential applications in mechanochemistry, energy and other fields are highlighted in conclusion.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Alessio Zaccone, Laurence Noirez. Universal G ∼ L −3 law for the low-frequency shear modulus of confined liquids. 2020. ⟨hal-03105598v1⟩