Molecular simulations of new ammonium-based ionic liquids as environmentally acceptable ...

181 Pages·2017·5.06 MB·English

Molecular simulations of new ammonium-based ionic
liquids as environmentally acceptable lubricant oils
Ana Catarina Fernandes Mendonça
To cite this version:
Ana Catarina Fernandes Mendonça. Molecular simulations of new ammonium-based ionic liquids as
environmentally acceptable lubricant oils. Other. Université Blaise Pascal - Clermont-Ferrand II,
2013. English. ￿NNT: 2013CLF22341￿. ￿tel-00857336￿
HAL Id: tel-00857336
https://theses.hal.science/tel-00857336
Submitted on 3 Sep 2013
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N◦ d’ordre: D.U.2341
UNIVERSITE BLAISE PASCAL
U.F.R.SciencesetTechnologies
ECOLE DOCTORALE DES SCIENCES FONDAMENTALES
N◦ 743
THESE
pre´sente´epourobtenirlegradede
DOCTEUR D’UNIVERSITE
(Spe´cialite´ : ChimiePhysique)
Par MENDONC¸ A Ana Catarina
MasterenChimie
Molecular Simulations of New Ammonium-based Ionic
Liquids as Environmentally Acceptable Lubricant Oils
Simulationsmole´culairesd’unenouvelleclassedeliquidesioniquesbase´ssurla
fonctionammoniumpourl’utilisationpotentielleentantqu’huileslubrifiantes
respectueusesdel’environnement
Soutenuepubliquementle21Fe´vrier2013,devantlacommissiond’examen:
Pre´sidentduJury: DominicTILDESLEY(Pr-CECAM)
Rapporteur: GuillaumeGALLIERO(Pr-UPPA)
Rapporteur: MathieuSALANNE(M.C.-UPMC)
Directeur: Ag´ılioPA´DUA(Pr-UBP)
Co-Directeur: PatriceMALFREYT(Pr-UBP)
Examinateur: SusanPERKIN(Dr.-U.Oxford)

Acknowledgments
Thisthesisistheworkofthreeyears. Threefastyears,forsomeonethathadneverseriouslytoucheda
computersimulationcodeoraCprogrambeforestartingthethesis. Andthisisit,andIdidit. Andof
course,nothingcouldhavehappenedwithouttheguidance,teachings,supportandintelligentadvices
of my thesis supervisors, Prof. Ag´ılio Pa´dua and Prof. Patrice Malfreyt. To them, I would like to
expressmydeepgratitude.
At the beginning everything was new: the work, the country, the city, the lab, the language and the
colleagues. These, werecrucialinmyintegrationandandI’mverygratefultoallofthem. Inpartic-
ular to Margarida Costa Gomes, a great woman and scientist that never refused to give me an advice
andwithwhomIwillcertainlymisstotalk.
I would also like to extend my thanks to other colleagues that also became my friends. They are
Gae¨lle Filippini, Yohann Coulier, Olivia Fandin˜o, Joa˜o Franc¸a, Ajda Podgorsek, Moise´s Curras, Al-
fonso Pensado and Marina Macchiagodena. Between them, my special thanks goes to Gae¨lle, the
personwhosharedtheofficewithmeduringmostofthetime. Thankyouforyourpatience,IknowI
canbeannoying,speciallywhenIspeakbymyselforgetnervous. Youarethebest!
Another very important person in all this period is Leila Moura. I was very lucky to have her here
withme,shehasbeenmybestfriendandIhopeourfriendshiplastsforever. Youcanalwayscounton
metosupportyouwhenthetimecomes,justasyouhavebeentheretosupportedme.
IwishtothankYuryFominfortheworkcollaboration,andthetechnicalsupportof: FlorentGoujon,
his teachings and of course, his marvelous homemade chocolates were very useful; Stefan Eder, for
his help with Lammps; Lucia Pisarova and Aline Walter for density, viscosity and surface tension
measurementsinthechemicalssimulatedinthiswork.
IwouldliketothanktheMarieCurieActionsandtheMINILUBESproject,forthefinancialsupport
and for the professional and human experiences. The project allowed me to meet great people from
differentcountriesandamongthemIwishtothankLuciaPisarova,AdinaNeacsu,FrancescoPagano,
ParvinZareandStephanieSteudte. AspecialthanksgoestoMr. JanotkaandDr. Do¨rrfortheproject
coordination and management. Thanks to this project and its numerous meetings I was able to visit
12 countries and attend more than 50 flights in the last three years! But besides the social aspect,
there is an important professional experience coming out from this European project, in the form of
interestingtrainingsandtheparticipationtofourinternationalconferences.
WhenIleftmycountry(Portugal)Ialsoleftapartofmyheartwithmyfamily. Inparticularmypar-
ents, my brother, my sister-in-law, my nephews, my grand-mothers, my godfathers and my cousins.
Thank you for your support and encouragement through all my years of study, including these last
three,despitethedistance. Iwillalwaysloveyou.
IwouldalsoliketothankallthefriendsIleftinPortugal. Mostofthemcametovisitme,givingme
thestrengthtocontinue.
Finally,butnotlessimportant,IwishtothankBruno. Inevercouldhavemadeitwithoutyou,without
yourloveandsupport.
Acomputerislikeahorse,itwillsenseweakness.
GregWettstein

Abstract
The aim of the present work is to understand at the molecular level the structure and interactions of
ionic liquids at metallic surfaces, using molecular dynamics simulations, and to investigate the im-
pactthatthesemicroscopicfeaturescanhaveinthetribologicalpropertiesofthesystem. Thechosen
ionic liquids as potential lubricant oils present suitable ecotoxic and biodegradable properties and
appropriate tribological characteristics. They are based in alkylammonium cations combined with
alkylsulfonateandbistriflamideanions. Ourstudyisdividedinfourparts, startingfromtheanalyses
of pure ionic liquids solutions and evolving to systems of ionic liquids confined between surfaces of
iron,attheequilibrium,undershearandalsointhepresenceofwater.
Structuralanddynamicpropertiesofionicliquidsareinvestigatedintermsofthesite-siteradialdistri-
butionfunctionsandtheself-diffusioncoefficients. Thepresenceofcharge-orderingandtheformation
ofmicro-domainsinsolutionarediscussed,aswellasthediffusivebehavioroftheionicspecies.
Anatomisticforcefieldforionicliquidsinteractingwithametalsurfacewasbuiltbasedonquantum
methods. Densityfunctionalcalculationsofalkylammoniumcations,alkylsulfonateandbistriflamide
anionsinteractingwithaclusterofironatomsareperformed,ataseriesofdistancesandorientations.
A site-site potential function was then adjusted to the DFT interactions energies, to obtain the force
field parameters. Finally, the polarization of the metal by the ions was taken into account using in-
viii
duced dipoles to reproduce the interaction energy between charges and a conductor surface. Using
this interaction model, molecular dynamics simulations were performed to study the structure of the
interfaciallayerofseveralionicliquidsataflatironsurface,includinganalysesofthepositionaland
orientationalorderingoftheionsnearthesurface,andchargedensityprofiles.
Non-equilibriummoleculardynamicssimulationsofionicliquidsinteractingwithironsurfaceswere
carriedoutusingthespecificsetofinteractionparametersdevelopedpreviously. Aprocedurewasde-
velopedforaquantitativepredictionofthefrictioncoefficientatdifferentloadsandshearrates,based
in a definition of pressure measured locally. The dependence of friction on the load, shear velocity,
surface topology and length of alkyl side chains in the ionic liquid was investigated. The changes in
the frictional forces were explained in terms of the specific arrangements and orientations of groups
formingtheionicliquidatthevicinityofthesurface.
Finally,theeffectofthepresenceofwaterinasmallquantityinanionicliquidsolutionisalsostudied
at equilibrium and non-equilibrium. An interaction potential was build that describes the interaction
betweenwaterandanironsurface,usingthesameapproachdescribedpreviously. Preliminaryresults
arepresentedonthestructureatthemetal–liquidinterfaceandfrictioncoefficient,andcomparedwith
thepureionicliquids.
Keywords: Ionicliquids,metallicsurfaces,interactionmodel,moleculardynamicssimulations,fric-
tion,non-equilibriummoleculardynamics,pressuretensor
Re´sume´
L’objectif de ce travail est de comprendre la structure et les interactions des liquides ioniques au
contactdesurfacesme´talliquesa` l’e´chellemole´culaireenayantrecoursauxme´thodesdedynamique
mole´culaire. Il s’agit e´galement d’e´tudier l’impact de ces caracte´ristiques microscopiques sur les
proprie´te´s tribologiques du syste`me. Les liquides ioniques choisis en tant qu‘huiles lubrifiantes po-
tentielles pre´sentent des proprie´te´s biode´gradables et des caracte´ristiques tribologiques approprie´es.
Ilsreposentsurdescationsalkylammoniumcombine´savecdesanionsalkylsulfonateetbistriflamide.
Notre e´tude est structure´e en quatre parties. Elle commence par l’analyse des liquides ioniques purs
puis, des liquides ioniques confine´s entre deux surfaces de fer a` l’e´quilibre et sous cisaillement, et
enfin,enpre´senced’eau.
Les proprie´te´s structurales et dynamiques des liquides ioniques sont e´tudie´es a` travers la fonction de
distributionradialeetlescoefficientsd’auto-diffusion. L’organisationdeschargesainsiquelaforma-
tiondemicro-domainesensolutionsonte´tudie´esconjointementaucomportementdiffusifdesespe`ces
ioniques.
Unchampdeforcesatomique,base´ surdesme´thodesquantiques,ae´te´ de´veloppe´ pourmode´liserles
interactions entre les liquides ioniques et la surface me´tallique. Des calculs DFT ont e´te´ re´alise´s sur
desfragmentsdeliquidesioniqueseninteractionavecunclusterdeferenfonctiondeladistanceetde