Freezing water under nanoscale confinement

Internship proposal

Laboratoire Sciences et Ingénierie de la Matière Molle, (SIMM)

Address: ESPCI, 10 Rue Vauquelin 75005 Paris

Head: Jean-Baptiste d’Espinose

Supervisors: Jean Comtet, Guilhem Mariette

Contact : / https://blog.espci.fr/jcomtet/

Context:
At the nanoscale, water exhibits remarkable deviations from bulk behavior. When confined between solid surfaces, it forms ordered hydration layers that display viscoelastic and even yield-stress properties. Previous dynamic atomic force microscopy (AFM) studies revealed a strong dependence of these behaviors on surface hydrophilicity, suggesting that interfacial water undergoes a confinement-induced slowdown reminiscent of glassy or supercooled dynamics.

Objective:
The goal of this internship is to deepen our understanding of the nonlinear rheology of confined water and to identify the microscopic mechanisms governing the transition from fluid-like to solid-like behavior under nanometric confinement.

Proposed Work:
– Perform dynamic AFM measurements in controlled environments (humidity, temperature, and ionic concentration) to explore how these parameters influence relaxation dynamics.
– Develop or adapt viscoelastic and activation models (Eyring, Maxwell, or extended phenomenological frameworks) to quantitatively describe the observed transitions.
– Compare hydrophilic and hydrophobic substrates to clarify the role of surface chemistry and wettability in determining interfacial water mobility and slippage.

Expected Outcomes:
The internship will provide insights into the microscopic origins of nanoconfined water’s viscoelasticity, contribute to a better understanding of nanoscale friction mechanisms, and potentially help design superlubric or anti-stiction surfaces in micro- and nanofluidic systems.

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