Webinar: The Use of Atomistic Simulations to Guide the Derivation and Verification of Molecular Theories
- Webinar: Computational Science and Engineering of Complex Materials - The SimEA ERA Chair Initiative
- Date: Tuesday, 15 June 2021
- Time: Starts: 16:00
- Venue: Live streaming of the discussion will be available on Zoom (Password: VsSCz1)
- Speaker: Pavlos S. Stephanou, Assistant Professor, Cyprus University of Technology
CaSToRC, the HPC National Competence Centre,
invites you to the SimEA Online Seminar Series
About the SimEA project Seminar Series
The SimEA project Seminar Series aims at promoting and disseminating scientific knowledge, focusing on Computational Science and Engineering, by featuring prominent researchers from around the world presenting their views and addressing key questions.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 810660.
Polymeric chains are characterized by a broad spectrum of length and time scales, which give rise to properties that are totally different from those of simple Newtonian liquids. Our aim in this work is to contribute to the understanding of the complex interplay between microscopic chain configurations or conformations and macroscopic behaviour, which is a central goal in polymer science and technology and a prerequisite for the design of improved polymers tailored for specific applications.
Firstly, guided from the reptation theory of de Gennes and Doi/Edwards, we will first show how one can predict the linear viscoelastic properties of polymer melts comprised of long polymer chains by using atomistic trajectories from detailed molecular dynamics (MD) simulations to calculate the primitive path (PP) segment survival probability function ψ(s,t) for entangled melts. This function is a cornerstone of the Doi/Edwards reptation theory but also of all tube models. Direct comparison of the theoretical predictions with the simulation data and previously reported experimental measurements in the literature are in complete accord.
Secondly, we combine MD simulations and the Rouse theory suitably adapted for polymer chains adsorbed by one or both of their ends to offer a quantitative description of local structure and microscopic dynamics in attractive polymer nanocomposite melts using as a model system poly(ethylene glycol) (PEG)-silica nanocomposites. Our work reveals that adsorbed polymer segments in the form of tails and loops on silica exhibit appreciable mobility locally. The simulations also reveal that PEG chains terminated with hydroxyl groups are primarily adsorbed on the silica surface by their ends, giving rise to a brush-like structure, whereas PEG chains terminated with methoxy groups are adsorbed equally probably along their entire contour. Direct comparison of simulation and theoretical predictions, in which information from the MD simulations are used as input, with previously reported experimental data in the literature for the dynamic structure factor for the same systems under the same temperature and pressure conditions reveals excellent agreement.
About the Speaker
Dr. Pavlos S. Stephanou graduated from the Department of Chemical Engineering, University of Patras, Patras, Greece in 2006. He then pursued postgraduate studies at the same department under the guidance of Prof. Vlasis Mavrantzas. His PhD thesis is entitled “Development of scale-bridging methodologies and algorithms founded on the outcome of detailed atomistic simulations for the reliable prediction of the viscoelastic properties of polymer melts”.
During his postgraduate career, he has worked at the University of Cyprus (Cyprus), ETH Zürich (Switzerland), the Cyprus University of Technology (Cyprus), and Novamechanics Ltd (Cyprus), having received numerous grants and awards. He received the «Cyprus Research Award – Young Researcher 2015» (Thematic area: Physical Sciences and Engineering) for his research work entitled «Modelling the viscoelasticity of polymer-based nanocomposites guided by principles of non-equilibrium thermodynamics», which was undertaken at the University of Cyprus (Department of Mathematics and Statistics) between 2011-2014 by the Research Promotion Foundation (RPF) of Cyprus on November 23rd 2015. The "Cyprus Research Award - Young Researcher" ("Young Researcher" being one who has a maximum of seven years of research experience from his/her doctoral title until the date of the announcement of the competition) is awarded to young researchers who have carried out specific research work of high quality, which has been completed within the last three years before the competition is announced.
Since September 2019, he is an Assistant Professor at the Department of Chemical Engineering of the Cyprus University of Technology.
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- Date: Tuesday, 15 June 2021
- Time: Starts: 16:00
- Speaker: Dr. Pavlos S. Stephanou, Assistant Professor, Cyprus University of Technology