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dc.contributor.authorTang, Yanfei
dc.contributor.authorGrest, Gary S.
dc.contributor.authorCheng, Shengfeng
dc.date.accessioned2019-02-04T14:18:25Z
dc.date.available2019-02-04T14:18:25Z
dc.date.issued2018-06-19
dc.identifier.issn0743-7463
dc.identifier.urihttp://hdl.handle.net/10919/87424
dc.description.abstractLarge scale molecular dynamics simulations for bidisperse nanoparticle suspensions with an explicit solvent are used to investigate the effects of evaporation rates and volume fractions on the nanoparticle distribution during drying. Our results show that "small-on-top" stratification can occur when Pe sϕ s ≳ c with c ∼ 1, where Pe s is the Péclet number and ϕ s is the volume fraction of the smaller particles. This threshold of Pe sϕ s for "small-on-top" is larger by a factor of ∼α2 than the prediction of the model treating solvent as an implicit viscous background, where α is the size ratio between the large and small particles. Our simulations further show that when the evaporation rate of the solvent is reduced, the "small-on-top" stratification can be enhanced, which is not predicted by existing theories. This unexpected behavior is explained with thermophoresis associated with a positive gradient of solvent density caused by evaporative cooling at the liquid/vapor interface. For ultrafast evaporation the gradient is large and drives the nanoparticles toward the liquid/vapor interface. This phoretic effect is stronger for larger nanoparticles, and consequently the "small-on-top" stratification becomes more distinct when the evaporation rate is slower (but not too slow such that a uniform distribution of nanoparticles in the drying film is produced), as thermophoresis that favors larger particles on the top is mitigated. A similar effect can lead to "large-on-top" stratification for Pe sϕ s above the threshold when Pe s is large but ϕ s is small. Our results reveal the importance of including the solvent explicitly when modeling evaporation-induced particle separation and organization and point to the important role of density gradients brought about by ultrafast evaporation.
dc.format.extentPages 7161-7170
dc.format.extent10 page(s)
dc.format.mediumPrint-Electronic
dc.languageEnglish
dc.publisherAMER CHEMICAL SOC
dc.relation.urihttp://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000436022900021&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=930d57c9ac61a043676db62af60056c1
dc.rightsIn Copyright (InC)
dc.rightsThis Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectScience & Technology
dc.subjectPhysical Sciences
dc.subjectTechnology
dc.subjectChemistry, Multidisciplinary
dc.subjectChemistry, Physical
dc.subjectMaterials Science, Multidisciplinary
dc.subjectChemistry
dc.subjectMaterials Science
dc.subjectSOLVENT EVAPORATION
dc.subjectCOLLOIDAL DISPERSIONS
dc.subjectPOLYMER-FILMS
dc.subjectAUTOSTRATIFICATION
dc.subjectPARTICLES
dc.subjectDYNAMICS
dc.subjectCOATINGS
dc.subjectDRIVEN
dc.subjectMD Multidisciplinary
dc.subjectChemical Physics
dc.titleStratification in Drying Films Containing Bidisperse Mixtures of Nanoparticles
dc.typeArticle - Refereed
dc.date.updated2019-02-04T14:18:24Z
dc.description.versionPublished (Publication status)
dc.title.serialLANGMUIR
dc.identifier.doihttps://doi.org/10.1021/acs.langmuir.8b01334
dc.type.otherArticle
dc.type.otherJournal
dc.identifier.volume34
dc.identifier.issue24
dc.identifier.orcidCheng, Shengfeng [0000-0002-6066-2968]
dc.identifier.pmid29792029
dc.identifier.eissn1520-5827
pubs.organisational-group/Virginia Tech/Science
pubs.organisational-group/Virginia Tech
pubs.organisational-group/Virginia Tech/All T&R Faculty
pubs.organisational-group/Virginia Tech/Science/Physics
pubs.organisational-group/Virginia Tech/Science/COS T&R Faculty


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