Bienvenu(e)!
» Identification
» Créer un nouveau profil
ESPCI. Experimental Molecular Dynamics - Watching individual liquid molecules moving at solid/liquid interfaces
Envoyé par jean.comtet@espci.fr
|
ESPCI. Experimental Molecular Dynamics - Watching individual liquid molecules moving at solid/liquid interfaces mercredi 22 janvier 2025 02:02:24 |
PhD thesis proposal - ED397 - Physics and Chemistry of Material
Experimental Molecular Dynamics - Watching individual liquid molecules moving at solid/liquid interfaces
Contact : J. Comtet - jean.comtet@espci.fr - [blog.espci.fr]
SIMM Laboratory, ESPCI PSL, CNRS, SU, 10 rue Vauquelin, 75005 Paris
Figure. (A) Schematic of the Single-Molecule fluorescence Microscopy set-up. The solid/liquid interface is selectively excited by an evanescent wave and imaged with a sensitive EMCCD camera. (B) Zoom on the local liquid melt structure, made of interacting polymeric molecules. Some polymers are tagged with a single fluorophore, allowing to follow their spatiotemporal trajectories. (C) Typical fluorescent signal on the EMCCD camera, with a single diffraction-limited spot related to the emitting fluorophore, localized and tracked with nanometric resolution and high temporal resolution (10 ms). (D) Preliminary results showing typical trajectories of PEG macromolecules adsorbed at the solid/water interface and dragged by a hydrodynamic flow of solvent.
Molecular-scale interactions between liquids and solid surfaces govern a wide range of processes in soft-matter physics, from wetting and friction, down to confined flows in nanofluidic settings, with broad relevance for a variety of fields from biology to engineering. Under confinement, surfaces can also to the specific emergence of peculiar and exotic behaviors for liquid transport. Typically, these interactions are probed at an ensemble level and described by averaged phenomenological coefficients accounting for the behavior of the interface, e.g. a slip length in the case of the interfacial solid/friction. However, the molecular foundations behind this averaged vision remain unclear, due to our current inability to experimentally observe the intrinsically nanoscale molecular processes taking place between liquid molecules and surfaces at interfaces and in confinement.
In this PhD proposal, we aim to bridge this gap by developing novel experimental approaches to directly visualize and quantify molecular motion at solid/liquid interfaces, which has been so far exclusive to molecular dynamics simulations. To do so, we will rely on state-of-the-art single-molecule and super-resolution fluorescence microscopy techniques which can be used to localize and track the motion of individual fluorophores with nanoscale resolution and high temporal resolution. We propose to apply these single-molecule imaging approaches to model liquids composed of dense polymeric melts (e.g. PDMS molecules), whose relaxation time and viscosity can be tuned over large time-scales through the control of their molecular weight or temperature. As shown in Fig. B, a fraction of these polymeric molecules will be tagged with a fluorophore. By selectively imaging the interface with an evanescent wave, we will be able to directly track the dynamical motion of individual macromolecules (Fig. C) and analyze their statistical properties. Note that preliminary results in our group focusing on the interfacial dynamics of dilute flowing polymer solutions have demonstrated the feasibility of this single-macromolecule tracking approach (Fig. D).
We propose to take advantage of these novel approaches to focus on three key long-standing problems related to interfacial liquid friction at the molecular scale: dissipation during the triple-line motion droplet, solid/liquid friction and interfacial liquid slippage and liquid transport in nanometric-scale confinement. We will play in these three cases on liquid-surface interactions through the control of surface physicochemistry, as well as liquid dynamics through the control of melt molecular weight and temperature. These single molecule measurements will be coupled with detailed statistical analysis of the dynamics, allowing ultimately to reveal a new molecular vision of liquid transport at solid surfaces.
We are looking for a PhD candidate motivated by state-of-the-art experimental approaches involving custom-made single-molecule imaging and statistical analysis and with a strong a background in physics (soft matter, hydrodynamics, mechanics…) or physicochemistry (polymers…)
References.
Comtet et al. (2020). Nature Nanotechnology, 15(7), 598-604.
Schwartz et al. (2014). JACS, 136(4), 1327-1332.
Modifié 1 fois. Dernière modification le 05/02/25 13:21 par Webmaster EDPIF.
Experimental Molecular Dynamics - Watching individual liquid molecules moving at solid/liquid interfaces
Contact : J. Comtet - jean.comtet@espci.fr - [blog.espci.fr]
SIMM Laboratory, ESPCI PSL, CNRS, SU, 10 rue Vauquelin, 75005 Paris
Figure. (A) Schematic of the Single-Molecule fluorescence Microscopy set-up. The solid/liquid interface is selectively excited by an evanescent wave and imaged with a sensitive EMCCD camera. (B) Zoom on the local liquid melt structure, made of interacting polymeric molecules. Some polymers are tagged with a single fluorophore, allowing to follow their spatiotemporal trajectories. (C) Typical fluorescent signal on the EMCCD camera, with a single diffraction-limited spot related to the emitting fluorophore, localized and tracked with nanometric resolution and high temporal resolution (10 ms). (D) Preliminary results showing typical trajectories of PEG macromolecules adsorbed at the solid/water interface and dragged by a hydrodynamic flow of solvent.
Molecular-scale interactions between liquids and solid surfaces govern a wide range of processes in soft-matter physics, from wetting and friction, down to confined flows in nanofluidic settings, with broad relevance for a variety of fields from biology to engineering. Under confinement, surfaces can also to the specific emergence of peculiar and exotic behaviors for liquid transport. Typically, these interactions are probed at an ensemble level and described by averaged phenomenological coefficients accounting for the behavior of the interface, e.g. a slip length in the case of the interfacial solid/friction. However, the molecular foundations behind this averaged vision remain unclear, due to our current inability to experimentally observe the intrinsically nanoscale molecular processes taking place between liquid molecules and surfaces at interfaces and in confinement.
In this PhD proposal, we aim to bridge this gap by developing novel experimental approaches to directly visualize and quantify molecular motion at solid/liquid interfaces, which has been so far exclusive to molecular dynamics simulations. To do so, we will rely on state-of-the-art single-molecule and super-resolution fluorescence microscopy techniques which can be used to localize and track the motion of individual fluorophores with nanoscale resolution and high temporal resolution. We propose to apply these single-molecule imaging approaches to model liquids composed of dense polymeric melts (e.g. PDMS molecules), whose relaxation time and viscosity can be tuned over large time-scales through the control of their molecular weight or temperature. As shown in Fig. B, a fraction of these polymeric molecules will be tagged with a fluorophore. By selectively imaging the interface with an evanescent wave, we will be able to directly track the dynamical motion of individual macromolecules (Fig. C) and analyze their statistical properties. Note that preliminary results in our group focusing on the interfacial dynamics of dilute flowing polymer solutions have demonstrated the feasibility of this single-macromolecule tracking approach (Fig. D).
We propose to take advantage of these novel approaches to focus on three key long-standing problems related to interfacial liquid friction at the molecular scale: dissipation during the triple-line motion droplet, solid/liquid friction and interfacial liquid slippage and liquid transport in nanometric-scale confinement. We will play in these three cases on liquid-surface interactions through the control of surface physicochemistry, as well as liquid dynamics through the control of melt molecular weight and temperature. These single molecule measurements will be coupled with detailed statistical analysis of the dynamics, allowing ultimately to reveal a new molecular vision of liquid transport at solid surfaces.
We are looking for a PhD candidate motivated by state-of-the-art experimental approaches involving custom-made single-molecule imaging and statistical analysis and with a strong a background in physics (soft matter, hydrodynamics, mechanics…) or physicochemistry (polymers…)
References.
Comtet et al. (2020). Nature Nanotechnology, 15(7), 598-604.
Schwartz et al. (2014). JACS, 136(4), 1327-1332.
Modifié 1 fois. Dernière modification le 05/02/25 13:21 par Webmaster EDPIF.