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1. M.W.Matsen,Macromolecules,2012.2. M.G.Buonomenna,et.al.RSCAdv.,2012.3.C.M.Bates,et.al.,Macromolecules,2013.4.C.Tang,C.J.Hawker,et.al.Science, 2008.
5.R.D.GrootandP.B.Warren,J.Chem.Phys., 1997
The Effect of Additive Cyclic Blends on Linear Block Copolymer Domain Spacing Maxwell Rick1, Jessie Troxler2, Amy D. Goodson2, Julie N. L. Albert2, and Henry S. Ashbaugh21Benjamin Franklin High School, 2Tulane University
Abstract
AcknowledgementsThankyoutotheAlbertGroupandtheAshbaughGroupWethanktheNationalScienceFoundationforfinancialsupportthroughgrantsDMR-1460637andIIA-1430280,andtheGraduateResearchFellowshipProgram(ADG).
ConclusionsandFutureWork• Blendingcyclicblockcopolymersintotheirlinearanaloguesreducesdomain
spacinglinearly.• Blendingorderedcyclicblockcopolymersintodisorderedlinearblock
copolymerscanresultinorderedsystems.Thisrepresentsawaytoreducedomainspacing,aslowerχ valuesandchainlengthscorrespondtolowerdomainspacingbutmaybebelowtheODT.
• Moresimulationsofdifferentχ valuesandchainlengthswillbecarriedouttofurthertesttheeffectivenessofcyclic-linearblendstoinduceorder.
• Ultimately,thinfilmsimulationsarenecessary,asnanolithographyusesthinfilms(thesesimulationsareinthebulk,butshouldnothavecrucialdifferencestothinfilmsimulations).Cylindersimulations(seefigure1a)areanotherfuturepossibility,ascylindersarealsousedfornanolithography.
DissipativeParticleDynamics
Cyclic-LinearBlendDomainSpacing
. Order-DisorderTransition(ODT)
Figure1:Basedonchainlengthandcomposition,blockcopolymersselfassembleintonanoscalemorphologies(a)1,2 whichhaveavarietyofapplications.Thisworkfocusesonthelamellar(banded)morphology(a)1,2CyclicBCPs(b)formfeatures20-40%smallerthantheirlinearanalogues.
Figure4:CoarsegrainingallowsDPDtosimulatelargesystemsoverlongperiodsoftime5.
Application- Blockcopolymerscanbeusedfornanolithography.Fortherequiredscale,
thewidthofthelamellarbands(featuresize)mustbeassmallaspossible.Oneinterestingwaytoreducedomainspacingistousecyclicblockcopolymers insteadoflinearones.
- Cyclicblockcopolymersaremuchmoredifficulttosynthesizethanlinearones.- Thisresearchusessimulationtotesttheeffectivenessofusingcyclicblock
copolymerasanadditiveintolinearblockcopolymersofsimilarcompositiontoreducedomainspacing.
- Theorder-disordertransitionisthepoint(χNvalue)whereablockcopolymertransitionsfromadisorderedstatetoanorderedone(seefigure1a).
- LowχNvaluescorrespondtolowerdomainspacingbutmaybebelowtheODT.
- Addingsmallamountsoforderedcyclicblockcopolymerstodisorderedlinearblockcopolymersmayinduceorder.
PureLinearN=12 10%CyclicBlend25%CyclicBlendPureCyclicN=24
Figure7:AtchainlengthsN=8,N=12,andN=16,thenormalized(dividedbytheirrespectivepurelineardomainspacing)domainspacinghasastronglinearrelationshipwithpercentcyclicBCPintheblend.Foreachsimulation,a=65.
a=35(lowχ)
a=65(highχ)
Figure9:ComparisonofblendsofLinearN=12andCyclicN=24(whichhavesimilarpuredomainspacings)atdifferentχ values.Atthelowerχ value,orderedcyclicblockcopolymersareblendedintodisorderedlinearblockcopolymers.Atthehigherχvalue,bothlinearandcyclicareordered.Thelowerχ valueresultsinlowerdomainspacing.Domainspacingsareonlymeasuredfororderedsystems.
BlockCopolymerSelfAssembly
Figure23:Alamellarblockcopolymerwithonepolymertyperemoved
Figure34:Theprocessofblockcopolymernanolithography
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Figure5:DomainSpacingsaremeasuredusingradialdistributionfunctions.
Figure6:VisualMolecularDynamics(VMD)isusedtogeneratesnapshotsofthesimulatedpolymers.
AnalysisMethods
PureCyclic
N=8N=12N=16
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b)
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Blockcopolymers(BCPs)canbeusedastemplatesfornanolithography.Advancingtechnologydemandssmallerlithographicfeatures.CyclicBCPshavesmallerfeaturesthantheirlinearanaloguesbutaredifficulttosynthesizeinhighpurity.WeuseDPDsimulationtoinvestigatethepotentialofcyclicBCPsasanadditivetoshrinkdomainspacingoflinearBCPs.Wehavefoundastronglinearrelationshipbetweencycliccontentandreduceddomainspacing.Additionally,addinganorderedcyclicBCPcaninduceorderinanotherwisedisorderedlinearBCP.Thisapproachmayallowforfurthershrinkingofdomainspacing,asloweringtheparametersχ andNresultsinsmallerfeaturesbutpotentiallydisorderedsystems.
SCGL
Figure8:BlendsoflinearN=12+cyclicN=24ata=35(lowχ)showatransitionfromdisordertolamellarbetween10%cyclicand25%cyclic.r
dr
References
LinearN=12
CyclicN=24
PureCyclic
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