IMX Seminar Series - Porous Materials

We investigated the formation and mechanical, transport, aging… properties of multi-scale materials such as clays, cement, geopolymer, charcoals...

Concerning length-scales, I will introduce the concept of Potential of Mean Force, PMF,as a way to implement upscaling modeling from the nano-scale to micron-scale. As regards to time scales, I will introduce metadynamics concepts as a way to implement upscaling modelling from the time scale of the elementary chemical reaction to geological time scales.

A PMF is a free energy function representing in an effective way the interactions between objects (cement hydrates, clay platelets, etc.) at thermodynamics conditions. The PMF is therefore the key piece of information allowing to coarse-grained Physical Chemistry information in a meso-scale model formulation. The use of PMF offers a huge computational advantage as it allows a straight up-scaling to the meso-scale while keeping essential interactions information that are the hallmark of Physical Chemistry processes. Such a coarse-grained modeling integrates atomistic response into inter-particle potentials that fully propagate molecular scale information all the way to the meso-scale.

Concerning time scales, I will introduce the reactive replica exchange molecular dynamics (RExMD) to investigate the geological conversion of two important classes of gas-forming constituents of terrestrial organic matter (lignin and cellulose) into charcoal. This conversion takes place over a time window of hundreds of millions of years and has so far remained a no man’s land to theoreticians. Using reactive molecular dynamics and the RExMD framework,  I will show that one can now simulate the full transformation of cellulose and lignin into charcoal and its associated fluid phase under prevailing geological conditions.

Bio: Roland Pellenq is Director of Research at CNRS, the French Government Agency for Scientific Research at the EPiDaPo George Washington / CNRS joint laboratory and a Visiting Professor in the department of Physics at Georgetown University in Washington DC. Roland Pellenq is a computational materials scientist with a strong interest in the physics and mechanics of micro- and nanoporous materials and confined fluids. After a Master in Plasma Physics from Aix-Marseille University (France), He obtained a PhD in Chemical Physics from Imperial College London (UK) in 1994 and received his Habilitation degree in Physics from the University of Orléans (France) in 2000. Roland Pellenq's research is dedicated to the development of bottom-up simulation approaches (starting at an atomistic level of description) for a large variety of critical problems in energy and environment, ranging from hydrogen and CH₄ storage, CO₂ sequestration, shale gas to fundamentals of cement and concrete research and more recently on Urban Physics. R. Pellenq is the author or co-author of 250+ papers published in major peer reviewed scientific journals. He was the founder and head of the MIT-CNRS joint laboratory "Multi-Scale Material Science for Energy and Environment" located at MIT. (2012-2020). He now leads a research effort on Urban Physics linking city texture as seen through the prism of Statistical Physics and applied to environmental, public health and climate challenges named COMPLEX-Cities.

R. Pellenq received a number of research awards that include the  Prix Special du Jury, Trophées de l’Innovation from Aix-Marseille University in 2019 ; the Research Medal of the European Geomechanics association ALERT in 2018 ; The Appreciation award of the Engineering Mechanical Institute (EMI) of the US for his outstanding service to the community in the US and outside and dedication in 2017 ; the Young Researcher Award at the French Festival des Sciences et des Technologies in 2003 and the Young Researcher Award of the Division de Physique-Chimie of the Société Française de Physique in 2002.