Molecular Mechanisms in Tribology

Beilstein Nanotechnology Symposium 2018

2 – 4 October 2018

avendi-Hotel am Griebnitzsee, Potsdam, Germany

 

Scientific Program:

 

Roland Bennewitz / Leibniz Institute for New Materials

Astrid de Wijn / Norwegian University of Science and Technology

Summary

The Beilstein Symposium „Molecular Mechanisms in Tribology“ took place on Oct 2-4, 2018, in Potsdam. At Lake Griebnitzsee, 68 scientists from Europe and all over the world discussed mechanisms of friction and wear with an emphasis on molecular structure in sliding contacts and tribochemical reactions. The symposium comprised 20 excellent invited talks and two poster sessions with contributions of outstanding quality. The contributions and vivid discussions after talks, during the poster sessions, and in the evenings made the symposium a success.

Two main areas of research structured the content of the symposium: on the one hand studies on the role of the molecular structure for friction and wear and on the other hand studies of chemical reactions activated by shear in sliding contacts.

Fundamental studies of the structural dynamics at the molecular scale and related pathways of dissipation were presented by Nicola Manini (Milano) and Michael Urbakh (Tel Aviv). The latter reported on the emergence of friction anisotropy only in the dynamics of structural lubricity between layered materials. The role of water in lubrication was subject of several talks. Roland Netz (Berlin) explained how a careful treatment of the chemical potential of water molecules in simulations allows to predict the transition from hydrodynamic lubrication to boundary slip. The interaction of hydrated ions with hydrophobic surfaces and its role in lubrication was explored in experiments reported by Rosa Espinoza-Marzal (Urbana-Champaign). Nuria Espallargas (Trondheim) explained her progress in replacing oil-based lubricants in applications in contact with sea water by water-based molecular functionalization of the contacting surfaces. The change in friction due to water intercalation in layered materials was related to phonon density effects through an isotope experiment by Jeong Park (Daejeon). Collective effects on the friction of molecular assemblies were discussed by Romain Lhermerout (Oxford) for C60 molecules jammed in confinement, by Juliette Cayer-Barrioz (Lyon) for time-scales of relaxation in discontinuous sliding, and by Seong Kim (Penn State) who provided a thoughtful review on the relation between the molecular volume and the activation volume in stress-assisted processes. Novel molecular designs with tribological functions were introduced by Bart Weber (Amsterdam) for fluorescent molecules reporting their nanometer confinement, by Sissi de Beer (Twente) for lubricant molecules attached to syringe needles, and by Nicholas Spencer (Zürich) for looped polymers grafted to surfaces.

With respect to chemical reactions initiated by shear in sliding contacts, Nitya Gosvami (Delhi) and Robert Carpick (Philadelphia) reported results of molecular scale experiments addressing the formation of wear protection films from traditional lubricant additives and from nano-particle based additives. Michael Moseler (Freiburg) and Clelia Righi (Modena) showed atomistic simulations of chemical reactions between molecules and surfaces and discussed how the reaction products influence the evolution of the sliding interface. Atomistic simulations of Daniele Dini (London) explained how changes in the operation conditions of engines result in a change of chemical reactivity of detergents in the lubricating oil. Conformational changes in polymers sliding along surfaces where demonstrated by Ernst Meyer (Basel). The spatial variation of tribo-electrochemical reactions was revealed by experimental results of Kathy Wahl (Washington). Finally, recent progresses in biomolecular tribology were presented by Philippa Cann (London), who reported individual differences in the tribological denaturation of relevant proteins.

Additional topics were covered in the poster sessions, including friction of disordered systems, variation of friction across phase transitions, mechanical dissipation in contact between two-dimensional materials, or structures in confined liquid lubricants.

The contributions documented significant progress in our understanding of molecular processes in sliding contacts, driven by new atomistic modeling techniques and available computational power as well as by applications of the now advanced experimental methods of nanoscience. It became obvious that tribochemistry and structural development in the contact are strongly interconnected at the molecular scale. It can also be observed that studies of molecular mechanisms have the potential to establish productive links between fundamental scientific and applied tribology, as for example in the tribochemistry of lubricant additives. The scientific organizers of the symposium, Astrid de Wijn (Trondheim) and Roland Bennewitz (Saarbrücken) are grateful to the Beilstein-Institut for the financial support and for the excellent organization of this symposium.

Roland Bennewitz and Astrid de Wijn

Scientific Program

Talks

 

TUESday, 2 October

9:00
Welcome and Introduction

Chair: Dirk Dietzel

9:20
A molecular modelling perspective on the mechanisms governing tribological interactions across the scales
Daniele Dini / Imperial College London, UK

10:00
Molecular friction mechanisms of boundary films: a coupling of time and space scales
Juliette Cayer-Barrioz / École centrale de Lyon, France

10:40
Coffee break

11:10
Molecular mechanisms involved in shear-induced polymerization and tribochemical etching
Seong H. Kim / Pennsylvania State University, USA

11:50
Tribomechanics of vapor-hydrated polymer brushes
Sissi de Beer / University of Twente, The Netherlands

12:30
Lunch

 

Chair: Philippe Vergne

13:50
Analytic understanding and control of dynamical friction
Nicola Manini / University of Milan, Italy

14:30
Nanoscale insight into boundary-film lubrication
Rosa Espinosa-Marzal / University of Illinois at Urbana-Champaign, USA

15:10
Coffee break

15:40
Fluorescence microscopy visualization of (lubricated) multi-asperity contacts
Bart Weber / Advanced Research Center for Nanolithography, The Netherlands

16:20
Do denatured synovial fluid proteins lubricate artificial joints?
Philippa Cann / Imperial College London, UK

17:00
End of talks

 

POSTER SESSION - PART 1

17:30
Presentation and discussion of posters No. 1 to No. 19

19:30
End of poster session

19:30
Dinner

 

WEDNESDAY, 3 October

Chair: Ronen Berkovich

9:00
Pulling single molecular wires and nanoribbons
Ernst Meyer / University of Basel, Switzerland

9:40
Are buckminsterfullerenes "molecular ball bearings''?
Romain Lhermerout / University of Oxford, UK

10:20
Coffee break

10:50
Tribology of lubricated nanoscale sliding contacts
Nitya Nand Gosvami / Indian Institute of Technology Delhi, India

11:30
Friction properties of water intercalated 2D materials on hydrophilic substrates
Jeong Young Park, KAIST, South Korea

12:10
Lunch

 

13:50
EXCURSION

17:30
End of excursion

18:30
Dinner

 

POSTER SESSION - PART 2

20:00
Presentation and discussion of posters No. 20 to No. 38

22:00
End of poster session

 

THURSday, 4 October

Chair: Rémy Pawlak

9:00
Polymers on surfaces: chains, loops, gels, and the Burj Khalifa
Nicholas D. Spencer / ETH Zurich, Switzerland

9:40
Hydration friction in nano-confinement: from bulk via interfacial to dry friction
Roland R. Netz / Free University of Berlin, Germany

10:20
Coffee break

10:50
The lubrication mechanisms of water-based fluids
Nuria Espallargas / Norwegian University of Science and Technology, Norway

11:30
Quantitative tribocorrosion of nanocontacts to steel
Kathryn J. Wahl / US Naval Research Laboratory, USA

12:10
Lunch

 

Chair: Philip Egberts

13:30
Tribochemistry of lubricant materials by ab initio, QM/MM and high throughput approaches
M. Clelia Righi / Modena University, Italy

14:10
Sliding friction in junctions of layered materials
Michael Urbakh, Tel Aviv University, Israel

14:50
Coffee break

15:20
Mechano-chemical decomposition of organic friction modifiers with multiple reactive centres induces superlubricity of ta-C
Michael Moseler / Fraunhofer IWM, Germany

16:00
Mechanisms of antiwear tribofilm growth revealed in situ by single-asperity sliding contacts
Robert W. Carpick / University of Pennslvania, USA

16:40
Final words, farewell

16:50
End of program

19:00
Dinner

Poster

Part 1 - Tuesday, 2 October

 

No. 1:
A model for friction strengthening in layered materials
David Andersson / Norwegian University of Science and Technology

No. 2:
Interfacial bond formation and rupture in lubricated silicon-based nanoscale contacts
Andrea Arcifa / ETH Zurich

No. 3:
Tribology at the nanoscale: AFM based single polymer friction
Bizan N. Balzer / University of Freiburg

No. 4:
Hyaluronan - phospholipid interactions in nanolubrication: molecular dynamics study
Piotr Bełdowski / University of Technology and Life Sciences in Bydgoszcz

No. 5:
Electrical tuning of vibrational modes in transition metal dichalcogenides

Florian Belviso / Czech Technical University in Prague

No. 6:
Investigation of the normal load and contact stiffness effect on kinetic friction in the Prandtl-Tomlinson model

Ronen Berkovich / Ben-Gurion University of the Negev

No. 7:
Molecular kinetics and friction

Johanna Blass / INM - Leibniz Institute for New Materials

No. 8:
Overcoming nanoscale friction barriers in transition metal dichalcogenides
Antonio Cammarata / Czech Technical University in Prague

No. 9:
Single atomic layer removal of silicon via stress/water-associated bond breaking

Lei Chen / Southwest Jiaotong University

No. 10:
Frictional anisotropy of bilayer MoS2 during sliding
Victor E. P. Claerbout / Czech Technical University in Prague

No. 11:
Superlubricity in phospholipid bilayers due to the presence of graphene

Zbigniew Dendzik / University of Silesia in Katowice

No. 12:
Temperature scaling of contact aging rates on amorphous silica surfaces

Dirk Dietzel / University of Giessen

No. 13:
Insights into dynamic sliding contacts gleaned through conductive atomic force microscopy
Philip Egberts / University of Calgary

No. 14:
Why many liquids appear to solidify during squeeze-out – even when they don’t
Hongyu Gao / Saarland University

No. 15:
Molecular dynamics simulation of ion transport in carbon nanotubes and graphene nanopores
Xiang Gao / Tel Aviv University

No. 16:
Coupling of surface deformation to phononic modes in amorphous solids

Jan Grießer / University of Freiburg

No. 17:
CTAB aggregates and their friction with molecular dynamics
Johannes Hörmann / University of Freiburg

No. 18:
Pendulum AFM dissipation peaks and surface oxygen vacancies on SrTiO3
Marcin Kisiel / University of Basel

No. 19:
Dynamic shear properties of ionic and nonpolar lubricants in nanometer confinement
Günther Krämer / Saarland University

Part 2 - Wednesday, 3 October

 

No. 20:
Friction across molecular films of ionic liquid
Romain Lhermerout / University of Oxford

No. 21:
The ultralow nanofriction of hydrogenated fullerene-like carbon film

Zhao Liu / University of Basel

No. 22:
Nanotribology on metallic glasses under electrochemical control

Haoran Ma / INM – Leibniz Institute for New Materials

No. 23:
Static distortions, frictional anisotropy, and negative friction coefficient of superlubric graphite/h-BN heterojunctions

Davide Mandelli / Tel Aviv University

No. 24:
Limits of the Prandtl-Tomlinson model for sliding friction on the micrometer scale
Alper Özoğul / University of Jena

No. 25:
Atomic-scale sliding friction on contaminated surface
Wengen Ouyang / Tel Aviv University

No. 26:
Lifting and sliding experiments of single molecules at low temperature
Rémy Pawlak / University of Basel

No. 27:
Mechanisms of electrotunable friction in friction force microscopy experiments with ionic liquids

Karina Pivnic / Tel Aviv University

No. 28:
Understanding the limiting shear stress phenomenon on confined molecular fluids: a molecular dynamics analysis

Alejandro Porras-Vazquez / University of Lyon

No. 29:
Nanoscale friction of 2D transition metal dichalcogenides

Ales Rapuc / University Of Southampton

No. 30:
Friction anomalies at first-order transition spinodals: the charge density wave material 1T-TaS2
André Schirmeisen / University of Giessen

No. 31:
Friction force microscopy of Fe-Al-O spinel catalyst powder in ethanol
Itai Shahar / Ben Gurion University of the Negev

No. 32:
Structural changes and phase diagram of Ti doped MoS2
Andrea Silva / University of Southampton

No. 33:
The effect of surface properties on hydrogel friction
Rok Simič / ETH Zurich

No. 34:
Thermodynamics of nanoscale friction in the thermal Prandtl-Tomlinson model
Paola Torche / University of Southampton

No. 35:
Atomistic modeling of polymer friction
Robin Vacher / SINTEF MK Tribocorrosion

No. 36:
Conformations and cryo-force spectroscopy of spray-deposited single-strand DNA on gold
J. Guilherme Vilhena / University of Basel

No. 37:
The role of phonons in controlling friction
Niklas Weber / University of Göttingen

No. 38:
Setting boundary-element methods on FIRE
Yunong Zhou / Saarland University