On-chip purification of arc-discharge synthesized multiwalled carbon nanotubes via mobile liquid

146 Pages·2017·14.08 MB·English

by  Matti Hokkanen

DEPARTMENT OF PHYSICS
UNIVERSITY OF JYVÄSKYLÄ
RESEARCH REPORT No. 1/2017
ON-CHIP PURIFICATION OF
ARC-DISCHARGE SYNTHESIZED
MULTIWALLED CARBON NANOTUBES VIA
MOBILE LIQUID INTERFACE
BY
MATTI HOKKANEN
Academic Dissertation
for the Degree of
Doctor of Philosophy
To be presented, by permission of the
Faculty of Mathematics and Science
of the University of Jyväskylä,
for public examination in Auditorium KEM 1 of the
University of Jyväskylä on January 20th, 2017
at 12 o’clock noon
Jyväskylä, Finland
January 2017

Preface
The content of this thesis is based on research that was first envisioned during my
Master’sworkin2011andbefore,andthencarriedoutduringmy2012-2016graduate
studiesattheUniv.ofJyväskyläDept.ofPhysicsandNanosciencecenter.
Iamverygratefultomythesissupervisor,Prof.MarkusAhlskogforhistutelage
and support during our common journey since 2008 that first lead to my Master’s
thesis, andthen, toDoctorate. Notonly hasthis givenme anopportunity tolearn a
lotabout science,but alsoa privilegeto meetandwork withsome trulywonderful
peoplewhohavehelpedmealongmywayonnumerousoccasions.Sadly,onlysome
ofthesepeoplecanbeproperlyrecognizedhere.
First,mypastandpresentteammatesintheMolTechresearchgroupdeserve
great credit. Drs. Jarkko Lievonen, Davie Mtsuko, Olli Herranen and Peerapong
Yotprayoonsak taughtmeeverythingIknowabout thepracticalitiesofnanoscience,
from cleanroom work to sample fabrication and imaging techniques. Likewise, I
mentionmyclosecolleague,Mr.ShaoDongkai,withwhomIhavelearnedtogether.
IalsorecognizepastMaster’sstudentsandinternsoftheMolTechgroup,Mrs.
IlkkaPekkala,HannuPasanen,JoonasSaariandAnttiLukkarinenwhohaveworked
under mysupervision in variousprojects; unfortunately, I couldnot always givedue
attention to your work. And how could I possibly not mention Ms. Saara Lautala,
whose efforts were so vital in preparation of the last papers incorporated in this
thesis?Truly,Icouldnothavedonethiswithoutherhardwork.
Of my other co-workers, I must mention Mr. Roope Lehto and Prof. Jussi
Timonen, whose efforts enabled us to carry out the study described in the first paper
of this thesis. For the other two papers, I humbly recognize the assistance of Dr.
Tuomas Turpeinen, who helped me so muchwithout any incentive or requirement.
Prof.MattiHaukka,Dr.MargaritaBulatovaandDr.ElinaLaurilafromtheDept.of
Chemistryarerecognizedfortheirhelpduringthelatterstagesofmythesiswork.
From the Nanoscience center, laboratory engineers Mr. Antti Nuotajärvi, Mr.
Tarmo Suppula and Dr. Kimmo Kinnunen have always been friendly and helpful
towardsme;theircontinuedtechnicalsupporthas beenvitaltothiswork.Similarly,
the practicalities of this work could not have been managed without our helpful
departmentalofficestaff;Ireallyhopethefutureworksoutwellforyouall.
Thisworkwouldnothavebeenpossiblewithoutsupportfromourcolleagues
abroad.At theUniv. ofWitwatersrand,South Africa,Mr.Christopher Colemanand
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Dr. Rudolph Erasmus carriedoutRamanmeasurementson our samples, expanding
upontheeffortsofMr.JuhaKoivistoinenhereinJyväskylä.IntheUniv.ofKarlstad,
Sweden,Dr.KristerSvenssonlendedushisuniqueinstrumentationandexpertise.
And finally, Prof. Emmanuel Flahaut from CIRIMAT, Univ. of Toulouse, kindly
provideduswithmaterialsfortheexperimentsinthefinalpaper.
Duringtroubledtimes,Ihavealsobenefitedgreatlyfromthesupportofseveral
senior colleagues. Profs. Markku Kataja and Timo Sajavaara deserve recognition
forservinginthefollow-upgroupofmyPh.D.project;thosediscussionsbrought
greatrelieftome.Drs.AndreasJohansson,JuhaMerikoski,SamiRäsänenandPekka
Koskinenhavealwayshadtimeformyconcerns,whetherscientificorpersonal.This
was by no means an easy path for me to tread, and I believe the reassurance and
encouragementyouprovidedwaswhatultimatelyhelpedmeovertheworst.
From my years here at the Univ. of Jyväskylä, I will always remember my
friendsandstudentcolleagues.Mr.JussiViinikainenwasmyclosefriendthroughout
myundergraduateyears,whileMr.KostiTapiobecamemyclosestco-workerduring
my doctoral studies. Both of them have helped me in numerous ways over these
years,notleastwithcourseexerciseproblems.Iwouldalsoliketothankmygraduate
student colleagues past and present, with whom I’ve shared laboratories of the
Nanoscience Center: Mr. Shen Boxuan, Mr. Geng Zhuoran, Dr. Yaolan Tian, Dr.
Tommi Isoniemi, Dr. Svetlana Baieva, Mr. Andrii Torgovkin, Dr. Janne Lehtinen
and Dr. Tero Isotalo. Thank you for creating that unique spirit of openness and
collaborationthatmakestheNanoscienceCentersuchaspecialplace.
I also wish to thank my family: my father, Markku, has always been very
supportiveofmyacademicendeavours,andisoneofthepeoplewhohaveshared
myburdensthroughoutthisjourney;mymotherEila,who,alongwithEino,have
alwaysbeenwelcomingofmecomingtovisit,andremindedmeoftheotherthings
besidesthethesis;andmybrothers,VilleandEemil;thankyou!
FinancialsupportenablingthisThesisworkhasbeenprovidedbytheNational
GraduateSchoolin MaterialPhysics(NGSMP),theNational DoctoralProgramme
inNanoscience(NGS-NANO),andtheUniv.ofJyväskyläDepartmentofPhysics.I
gratefullyacknowledgetheirpatienceonthematter.
Finally,as itissaid thatscience isaboutstanding ontheshoulders ofgiants, so
Ialsostandwithnotjustthehelpoffellowscientists,butalsoeducatorsandteachers
whohavecherishedmyambitions.Assuch,Iwouldliketodedicatethisthesistoall
thepeoplewhohavetaughtmeovertheyears:Eija,Eila,Anneli,Tuomo,Arto,Vilho,
Yrjö,andeveryoneelse;thisisforyou.Imaynothavealwaysbeenabletoanswer
yourquestionscorrectly,butasitturnsoutscienceislessaboutgivinganswers,and
moreofknowingtoasktherightquestions.Thankyouallforwhatyoudo.
Jyväskylä,December2016
MattiHokkanen
Abstract
Hokkanen,Matti
On-chip purification of arc-discharge synthesized multiwalled carbon nanotubes
viamobileliquidinterface
Jyväskylä:UniversityofJyväskylä,2017,132p.
(Researchreport/DepartmentofPhysics,UniversityofJyväskylä,
ISSN0075-465X;1/2017)
ISBN978-951-39-6916-5(papercopy)
ISBN978-951-39-6917-2(e-print)
diss.
This thesis reports a novel approach for purification of carbon nanotube (CNT)
samples deposited on smooth silicon substrates through a mobile liquid interface
interactingwith carbonaceousdebrisparticles thatcontaminate the deposition.The
method is based on physical interaction of the particles and the three-phase con-
tact line via capillary interface forces, i.e. the surface tension, which results in the
detachmentofchemicallyindispersiblecolloidsfromthesamplesurface.
Intheexperimentsreportedinthiswork,wefocusprimarilyonarc-discharge
grownmulti-walledcarbonnanotubes,whosesynthesisisparticularlyplaguedby
carbonaceousdebristhatisdifficulttoremovewithoutharshchemicaltreatments.
Theirregulardebrisparticlesarepreferentiallycapturedbythemobilecontactline,
whiletubularCNTsareretainedinlargenumbersduetotheirappreciablystronger
adhesion. Our cleaning method has the added benefit that the intrinsic chemical
propertiesof the CNTs are fullypreserved, sinceno chemical treatmentsare needed;
onlyprerequisiteisthehydrophilictreatmentoftheunderlyingsubstrate,whichon
siliconwaferscanbeaccomplishedthroughoxygenplasma.
Various aspects of the cleaning process, including the effects of contact line
velocity, chemical composition of the immersion liquid, and the CNT orientation
relative tothe liquid frontare investigated inthis thesis.Furthermore, atomic force
microscopy (AFM) imaging and the image analysis methodology is discussed. Ad-
ditionally, we demonstrate some research applications that directly benefit from
our technique,e.g. microraman spectroscopy ofindividual carbon nanotubes, and
nanomechanicalinvestigationofsuspendedtubesviaAFM-deflectionmeasurements.
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Theoreticaltreatmentofthedetachmentprocessispresentedintheframework
developed for spherical microcolloids in existing works. In this model, the particle
detachmentisprimarilyattributedtothesurfacetensionforce.Otherforcesaffecting
the process include adhesion, whichin liquid electrolyte medium can be estimated
viatheDLVOadhesiontheory,andhydrophobicinteractions.
We conclude that the particle detachment is qualitatively well-explained by
the physical interactions at the contact line, while the selectivity of the process for
the irregular debris particles in favor of the tubular CNTs probably stems from
differencesinthemagnitudeoftheadhesionforce.Chemicalfactorsassociatedwith
thecompositionoftheimmersionliquidontheotherhandseemtoonlyhavevery
limitedeffectonthequantitativecleaningresult.RegardingtodetachmentofCNTs,
orientation-dependent behavioris implied, with speciesoriented perpendicular to
theadvancingcontactlinereflectingthegreatestprobabilitytoberetained.Overall,
the detachment of all particles is found to increase with decreasing velocity of the
liquid interface. These results are generally in qualitative agreement with existing
worksdealingwithsphericalmicrocolloids.
Keywords carbonnanotube,contactline,surfacetension,wetting,surfacechemistry,
adhesion,atomicforcemicroscopy
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Author MattiHokkanen
NanoscienceCenter
DepartmentofPhysics
UniversityofJyväskylä
Finland
Supervisor ProfessorMarkusAhlskog
NanoscienceCenter
DepartmentofPhysics
UniversityofJyväskylä
Finland
Reviewers Prof.MarinaRuths
DepartmentofChemistry
UniversityofMassachusettsLowell
USA
Dr.MarkoBurghard
NanoscaleScienceDepartment
MaxPlanckInstituteforSolidStateResearch,Stuttgart
Germany
Opponent Prof.OrenRegev
DepartmentofChemicalEngineering
Ben-GurionUniversityoftheNegev,BeerSheva
Israel
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Tiivistelmä (abstract in Finnish)
Hokkanen,Matti
On-chip purification of arc-discharge synthesized multiwalled carbon nanotubes
viamobileliquidinterface
Jyväskylä:UniversityofJyväskylä,2017,132p.
(Researchreport/DepartmentofPhysics,UniversityofJyväskylä,
ISSN0075-465X;1/2017)
ISBN978-951-39-6916-5(nid.)
ISBN978-951-39-6917-2(verkkoj.)
diss.
Tässä väitöskirjatyössä esitetään uusi lähestymistapa piipinnoille valmistettujen
hiilinanoputkinäytteiden(carbonnanotubes,CNT)puhdistamiseenhiilipohjaisista
kuonapartikkeleista liikkuvan nesterajapinnan avulla. Menetelmä perustuu partik-
kelienjanestepinnanväliseenfysikaaliseenkapillaarivuorovaikutukseen,elipinta-
jännitysvoimaan,kolmenfaasinrajapinnalla,jokaaiheuttaanesteeseenkemiallisesti
liukenemattomienkolloidienirtoamiseennäytepinnalta.
Keskitymmekokeellisessatyöskentelyssäerityisestivalokaarisyntetisoituihin
nanoputkiin, joiden synteesin yhteydessä syntyy runsaasti hiilipohjaisiakuonapar-
tikkeleitajoidenpoistaminenonhankalaailmanvoimakkaitakemiallisiakäsittelyjä.
Muodoltaan epäsäännölliset partikkelit ensisijaisesti tarttuvat mobiiliin nesteraja-
pintaan, kun taas putkimaiset hiilinanoputket jäävät enimmäkseen näytepinnalle
voimakkaamman adheesiovoiman ansiosta. Puhdistusmenetelmämme erityinen etu
on,ettähiilinanoputkienkemiallisetominaisuudetsäilyvätprosessissamuuttumat-
tomana, sillä niiden kemiallisia käsittelyä ei tarvita; ainoana edellytyksenä on sub-
straattipinnanhydrofiilisyyskäsittely,mikäpiilevyjentapauksessavoidaanhelposti
toteuttaahappiplasmalla.
Väitöskirjassatutkitaanuseitapuhdistusprosessiinliittyviätekijöitä,mukaanlu-
kien kontaktirajapinnan nopeus,immersionesteen kemiallinenkompositio jahiilina-
noputkien tapauksessa niiden orientaatio rajapintaan nähden. Lisäksi käsittelemme
kokeissahyödynnettävääatomivoimamikroskopiaa(atomicforcemicroscopy,AFM),
sekäsiihenliittyvääkuva-analyysimetodologiaa.Lopuksiesittelemmejoitakintutki-
mussovelluksia,jotkahyötyvätsuoraanpuhdistustekniikastamme,mukaanlukien
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yksittäisten nanoputkien raman-spektroskopia sekä vapaasti roikkuvien putkien
nanomekaanistenominaisuuksienmäärittäminenAFM-menetelmin.
Puhdistusprosessiin liittyvä teoreettinen käsittely perustuu aiemmissa töis-
sä pallomaisille mikrokolloideille kehitettyyn teoriaan. Tässä mallissa partikkelin
poistuma liitetään pääasiassa pintajännitysvoimaan. Tämän lisäksi prosessiin vai-
kuttavat hydrofobiset vuorovaikutukset, sekä adheesiovoima, joka nestemäisessä
ympäristössävoidaanilmaistank.DLVO-teorianavulla.
Tutkimuksenloppupäätelmätovat,ettäpartikkelienpoistumapinnoiltaonkva-
litatiivisestiymmärrettävissäkontaktilinjan fysikaalistenvuorovaikutustenpohjalta,
japrosessinselektiivisyysepäsäännöllisiinpartikkeleihinonseuraustananoputkiin
verrattuna eroavasta adheesiovoimasta. Nesteen kemiaan liittyvät tekijät näyttävät
toisaalta vaikuttavan verrattain vähän kvantitatiiviseen puhdistumistulokseen. Hii-
linanoputkien poistuman osalta havaittiin orientaatioriippuvaista käyttäytymistä,
jossaetenevänrajapinnankanssavastakkaisuuntaisestisuuntautuneetputketselvi-
sivättodennäköisimminnäytepinnaltairtoamatta.Kaikkienpartikkelienpoistuma
yleisestikasvaarajapinnannopeudenhidastuessa.Nämätuloksetovatyleisestikvali-
tatiivisella tasolla yhteensopivia aiempien, pallomaisia mikrokolloideja käsittelevien
tutkimustenkanssa.
Avainsanat carbonnanotube,contactline,surfacetension,wetting,surfacechemistry,
adhesion,atomicforcemicroscopy