Wednesday, October 23 12h00 MSG-025 Bernal Institute

Modelling the Impact of Molecular Interfaces Beyond the Atomistic Scale

ABSTRACT

In this talk, three examples of molecular interfaces, which have an impact beyond the atomistic scale in relevant engineering applications, and how to model them numerically will be discussed.

First, the focus will be on the role of water in molecular and nano materials. Molecular dynamics simulations are used to compute the self-diffusion coefficient of water within nanopores, around nanoparticles, carbon nanotubes and proteins. For almost 60 different cases, the diffusion coefficient is found to scale linearly with a dimensionless parameter, which represents the confinement degree of the water molecules[1]. Such relationship has accurately predicted the response of contrast agents for magnetic resonance imaging[1]. The Oak Ridge National Laboratory (ORNL) has validated experimentally and independently this relationship, beyond biomedical applications[2]. The same approach can be used also to study bio materials, e.g. proteins, polypeptides and amino acids[3].

Second, experiments and atomistic simulations are used to elucidate the non-trivial interplay between nanopore hydrophilicity and the overall water transport through zeolite crystals. A poor correspondence between the experiments and simulations has revealed the presence of a surface diffusion resistance at the interface between the zeolite porous matrix and water[4]. This suggests future experimental work to address these surface imperfections, as an essential prerequisite for improving water permeability of such membranes.

Finally, molecular interfaces for composite materials are investigated. The enhanced thermal properties of nanomaterials are important in many fields, from aerospace to electronics industries, from automotive to biomedical applications. Nevertheless, these properties are determined by phenomena spanning from the nano to the macro scale and, thus, should be simulated by tailored multi-scale techniques. Here the focus is on predicting the thermal conductivity of nanocomposites (epoxy matrix + carbon nanofillers) using fast mesoscopic models, whose input parameters come from both atomistic models (interface properties) and continuum models aided by machine learning (macroscopic corrections). The presented hybrid models, verified against commercial software and validated against experiments, may provide guidelines towards the technical-economical optimization of novel nanostructured materials with tunable thermal properties.

[1] E. Chiavazzo, M. Fasano, P. Asinari & P. Decuzzi, Nature Comm. 5, 3565, http://doi.org/10.1038/ncomms4565, (2014).

[2] S.O. Diallo, PRE 92, 012312, (2015).

[3] A. Cardellini, M. Fasano, E. Chiavazzo & P. Asinari, Physics Letters A, 380:20, pp. 1735-1740, https://doi.org/10.1016/j.physleta.2016.03.015, (2016).

[4] M. Fasano, T. Humplik, A. Bevilacqua, M. Tsapatsis, E. Chiavazzo, E.N. Wang & P. Asinari, Nature Comm. 7, 12762, https://doi.org/10.1038/ncomms12762, (2016).

ABOUT THE PRESENTER

Pietro Asinari is Full Professor of heat and mass transfer and Director of the Multiscale Modeling Laboratory (SMaLL, https://www.polito.it/small) at the Politecnico di Torino. He graduated with honors in Mechanical Engineering in 2001 and received his PhD in Energy Engineering in 2005, winning the ENI-Italgas award for Energy and the Environment. He is a member of the Management Committee of the European Council for Material Modeling (EMMC, https://emmc.info). He is an international member of the Advisory Committee of the American OpenKIM project (https://openkim.org) for interatomic models. He is a member of the Executive Committee of the Italian Union of Thermo-fluid dynamics (UIT). He is a member of the editorial board of the Journal Heliyon (Elsevier) since 2016. He is responsible for numerous European (eight projects in H2020) and national projects. His research lies in the field of energy and environmental sustainability, in particular regarding the use of renewable sources for the production of drinking water, the heat and mass transfer in energy devices, and the modeling of materials. He has published more than 100 articles in international journals, including Nature Sustainability and Nature.

Tea/coffee will be available at 11h45

For further information, please contact: ehtsham.u.haq@ul.ie