荧光超疏水(2)

Alltheelectrochemicalexperimentswereconductedinanelectrochemicalcell(1?1?4.5cm3)withathree-electrodesystembyusingacomputer-controlledCHI630EElectro-chemicalAnalyzer.Theworkingelectrodewasindiumtinoxide(ITO)glass(<10Usqà1,0.9?5cm2),successivelywashedunderultrasonicationwithdeionizedwaterandabsoluteethanol,andthendriedwithastreamofN2beforeuse.Thecounterelectrodewasplatinumwire(1mmdiameter),whichwascleanedbeforeeachexamination.AnAg/AgClwirewasusedasaquasi-refer-enceelectrode.Allelectrochemicalexperimentswereperformedatroomtemperatureand<40%relativehumidity.Electrochemicalpreparationofpolypyrenelms

PolypyrenelmswereelectrodepositedonITOelectrodesbycyclicvoltammetry(CV)between0and+1.5Vin0.03M

pyrene/

J.Mater.Chem.C,2015,3,2086–2092|2087

Published on 13 January 2015. Downloaded by Shanghai Jiaotong University on 19/0

View Article Online

JournalofMaterialsChemistryCPaper

ACNsolutioncontaining0.2MLiClO4asasupportingelectro-lyte.Thethicknessofthepolypyrenelmwastunedbycontrollingtheelectrodepositioncharge(Q)approximatelyat150?20mCcmà2.Beforecharacterization,alllmswererinsedwith50%ethanolsolution(about1mL)twotimesandthendriedatroomtemperatureforseveralminutesunderowingN2.

3/2015 02:44:39.

Preparationofthesilica-coatedsuperhydrophobicpolypyrenelms

Tocoverthepolypyrenelmswithsilicalayers,chemicalvapordeposition(CVD)ofTEOSwasperformedatroomtemperaturep-conjugatedpolymerlmsarea?ectedbytheelectrodematerials,appliedpotential,electrolytesolution,monomers,andevenconcentrationofthemonomers.Inourelectro-chemicalexperimentalsystem,theresultingpolypyrenelmpresentsapetal-likeroughmorphology,asrevealedbythescanningelectronmicroscopy(SEM)images(Fig.2a).ThemagniedSEMimageshowsinmoredetailthemicro/nano-meter-scaledrapestructure(Fig.2b).Thismorphologymaybeattributedtotheparticularelectrochemicalsystem.18–25

Thepolymerizationdegreeoftheelectrodepositedpoly-pyrenewasestimatedtobeabout6–11pyreneunits,whichmeansthattheresultingpolypyreneisonlyanoligomer(screenshotsinFig.S1?).Thiskindofanoligopyrenelmmayfor30h,thatis,thelmswereplacedinacloseddesiccatortogetherwithtwoopenvesselscontainingabout2mLofTEOSand1mLofaqueousammoniasolution,respectively.5b,12SilicalayerswereformedonpolypyrenelmsbyhydrolysisandcondensationofTEOScatalyzedbyammonia.5bThesilica-layer-encasedpolypyrenelmsretainedthepetal-likestructure.Tocreatesuperhydrophobicsilicacoatings,CVDofPOTSwasperformedatroomtemperaturefor12hinasimilarcloseddesiccatorinwhichthesilicacoatingswereplacedtogetherwithtwoopenvesselscontaining0.2mLofPOTSand0.2mLofaqueousammoniasolution,respectively.

Preparationoflarge-scaleandexionalFPSHlms

Thelarge-scaleandexionalFPSHlmswerepreparedonthestainlesssteelwovenwiremesh(100mesh,17?8cm2)andtheplastictransparentITO-PETlm(35?5Usqà1,5?3cm2).Inthethree-electrodeelectrochemicalsystem,thestainlesssteelwovenwiremeshortheplastictransparentITO-PETlmwasusedastheworkingelectrode,andthestainlesssteelwovenwiremeshelectrodewithalargerareathanthatoftheworkingelectrodewasusedasthecounter-electrode.Thepolypyrenelmswereelectrodepositedbyusingtheconstantpotentialof+1.5Vin0.03Mpyrene/ACNsolutioncontaining0.2MLiClO4asasupportingelectrolyte.ThethicknessofthepolypyrenewascontrolledbyusingQ?150?20mCcmà2.TheFPSHlmsonthestainlesssteelwovenwiremeshandtheplastictransparentITO-PETlmwerepreparedunderthesameCVDconditionsdemonstratedabove.

Resultsanddiscussion

Preparationandmorphologies

TheFPSHlmwascreatedfromanelectrodepositedpolypyrenelm.Inathree-electrodesystem,thepolypyrenelmwaselec-trodepositedonITOglassbyusingaCVmethodina0.03Mpyrene/acetonitrile(ACN)solutioncontaining0.2MLiClO4asasupportingelectrolyte(insetinFig.1a).Notethattheconcen-trationofthepyrenemonomerislimitedto0.03M,sinceahigherorlowermonomerconcentration(suchas0.05Mor0.01M)isunfavorabletoobtaintherequiredpolypyrenelm.Bycontrollingtheelectrodepositedcharge(Q)at150?20mCcmà2,auniformyellowpolypyrenelmcanbedeposited(seethephotographintheinsetofFig.1a).Ingeneral,themorphologyorthephotoelectricpropertiesofelectrodeposited

2088|J.Mater.Chem.C,2015,3,2086–2092befragileandeasytodamageunderanexternalimpactforcebecauseofitsrigidpyreneringstructure.22,24Toprotectthepeculiarroughnessmorphologyandimprovetheimpactresis-tance,wetriedtocovertheresultingpolypyrenelmwithasilicalayer.Forthispurpose,TEOScatalyzedbyammoniawasdepositedviaCVDinaclosedcontaineratroomtemper-ature.5b,12Aer30h,ahydrophilicpolypyrene/silicahybridcoatingwasformed.Toreduceitssurfaceenergy,another

CVD

Fig.2(a)Scanningelectronmicroscopy(SEM)imageofthepetal-likeporousstructureofthepolypyrene?lm.Insets:WCAmeasurementonthe?lm(WCA:ca.151.5???1??)(left);thewaterdroplet(4mL)didnotrollo?butremainedattachedtothesurfaceevenwhenthesurfacewasinverted(right).(b)Magni?edimageofthepolypyrene?lm.(c)SEMimageoftheresultingpetal-likeporousFPSH?lmafterCVDofTEOSand?uorination.Insets:theresultantFPSH?lmhadastaticWCAof163???1??(left)andthewaterdropletona4??tiltedFPSH?lmlostadhesionandrolledo?.(d)Magni?edimageoftheresultingFPSH?lm.(e)X-rayphotoelectronspectroscopyoftheFPSH?lm.(f)Force–distancecurvesrecordedforawaterdroplet(4mL)graduallyapproachingandretreatingfromtheFPSH?lmsurface.

Thisjournalis?TheRoyalSocietyofChemistry2015

Published on 13 January 2015. Downloaded by Shanghai Jiaotong University on 19/0

View Article Online

PaperJournalofMaterialsChemistryC

3/2015 02:44:39.

ofPOTSwasfurtherperformedinasimilarclosedcontaineratroomtemperaturefor12h.Aerthisstep,theFPSHlmwasready.WefoundthattheFPSHlmperfectlyinheritedthepetal-likeroughmorphologyofthepolypyrenelm(Fig.2c).ThethicknessoftheFPSHlmwasestimatedtobeapproxi-mately10mm(Fig.S2?).Furthermore,themagniedSEMimageoftheFPSHlmstillshowsthemicro/nanometer-scaledrapestructure,althoughthesilicalayerwiththethicknessofca.30–40nmwasdepositedontheunderlyingpolypyrenelm(Fig.2dandS3?).

Superhydrophobicityandself-cleaningproperties

Asuperhydrophobicsurfacewithawatercontactangle>150??maybeeitherawatersuper-adhesionsurfaceorawaterself-cleaningsurface,dependingontheroughstructureofthesurfaceandthesurfaceenergy.Thedetailsofthewettingpropertiescanbeconrmedbyexaminingthewaterslidingangle.Theas-preparedFPSHlmhasahighwatercontactangleof163???1??andasmallslidingangleofabout4???1??(insetinFig.2c),indicatingthattheFPSHlmisananti-adhesivecoatingwithself-cleaningability(MovieS1?).Owingtotheso-calledCassiesurfacestate,waterdropletsplacedonsuchcoatingssitontopofaircushionstrappedbeneaththedrop-lets.3Conversely,thepurepolypyrenelm,beforethedoubleCVDprocess,presentedasuper-adhesivesurfacewithaWCAof151.5???1??andabigslidingangle>90??evenwhenreversed(Wenzeladhesionstate;insetinFig.2a).11Thiswettingtransi-tionfromWenzeltoCassiestatescanbeattributedmainlytothesuccessfulintroductionoflowsurfaceenergyuorosilaneonthepetal-likeroughstructure,asevidencedbythestrongF1speakat691.8eVintheX-rayphotoelectronspectroscopy(XPS)measurement(Fig.2e).TheadhesionforcebetweenthewaterandtheFPSHlmsurfacewasalsoestimatedbydetectingtheforce–distancecurvesofawaterdroplet(4mL)movedclosertoandfarfromthelmsurface(Fig.2f).Themeasuredadhesionforcewasonlyabout10.2mN.Thisveryweakadhesionforcecouldnotpreventwaterdroplets(4mL)fromrollingawayfromtheFPSHlmsurface.

Opticalpropertiesandphotoluminescence

Fig.3aandbshowtheexcitationanduorescenceemissionspectraoftheFPSHlm,polypyrenelmanditsdimethylformamide(DMF)solution(theirUV-visspectraareshowninFig.S4?).Thepolypyrenelmshowedastrongemissionpeakcenteredat498.5nm(Fig.3a(red)),whenexcitedat408nm(theinsetofFig.3a(black)),andthelmemittedabrightblue-greenuorescencewhenexposedto365nmUVlight,demonstratingitsgooduorescenceproperties(Fig.3c(le)).Notably,thepolypyrenedissolvedinDMFexhibitedadi?erentemissionpeakcenteredat451.5nm(Fig.3b(blue))whenexcitedat349nm(Fig.3b(black)),whiletheemissionpeakcenteredat498.5nmpresentedintheuorescencespectrumofsolidpolypyrenedisappearedcompletely.Furthermore,thepolypyreneinDMFemittedabrightblueuorescence(under365nmUVlight)(Fig.3c(right)).Obviously,theuorescencepropertiesofthepolypyreneundergoasignicantchangewhenpassingfrom