Two- and Three-Dimensional Smectic Ordering of Single-Handed Helical Polymers(9)

(e)ARTICLES

poly-D-1(+)filmshowedasharpreflectionwithaspacingof14.3nminameridionaldirectionperpendiculartotheouterbroadreflectionof2.32nmbeingattributabletothelateralpackingofthepolymer(Figure4E).Thespacingof14.3nmisalmostidenticaltothatdeterminedbyAFM.22TheobservedspacingbySR-SAXSbecomeslongerwhenthemolecularlengthorrodlengthofthepoly-1’sislongerandthelayerspacingsdeterminedbySR-SAXSandAFMareingoodagreementtoeachother(FiguresS8andS9).AtheoreticalstudypredictedthatthesmecticorderingisnotfavoredforrodlikepolymerswithabroadMWD,sincetherodsofdifferentlengthsdonotpackintolayersaseffectivelyastherodofthesamelength.23Infact,poly-1’swithMWDsover1.15nolongershowedanysignofsmecticphases.Transmissionelectronmicroscopy(TEM)ofanultramicrotomedcastfilmofasmecticLCofpoly-D-1(+)showedabandedtexture(Figure4F)witharepeatdistanceofca.14nmcorrespondingtoitssmecticlayerrepeatasobservedbySR-SAXSmeasurements,22eventhoughthebandingrepeatdistancedependsonthelocalcontactanglebetweenthesampleandthediamondknife.24AFMobservationsofpoly-L-1(+)onHOPGalsorevealeda2Dsmecticlikeassemblyofthepolymerchainswithanaveragelayerspacingof5.8(2.2nm(Figure4G),andthepolarizedopticalmicrographofpoly-L-1(+)showedasimilarfan-shapedtextureina15wt%chloroformsolution(Figure4H),offeringconvincingproofforasmecticordering.

Conclusions

Insummary,wehavedemonstratedthatthepresenthelix-senseselectivelivingpolymerizationwiththeµ-ethynediylPt-Pdcatalystunprecedentedlyproducesbothright-andleft-handedhelical,rigid-rodpolyisocyanidesatoncewithpreciselydefinedarchitecturesincludingthemolecularlength,itsdistribution,andhandednessaswell,whichcanbefurtherseparatedintoeachhelixinafacileway.Moreimportantly,thesehelicalpolyiso-cyanidesareproventobeidealbuildingblocksfor2Dand3Dsmecticarrangementsonasubstrate,insolutionandthesolid

(21)Poly-PdD-1(+)wastreatedwithCuClinpiperidinetoeliminatereflectionsresiduesthecouldpriornottobetheobservedSR-SAXSmeasurements,sincethesmectictheterminal

layernotterminalPdresiduespreparedforunderthemagnetic-orientedidenticalconditions;polymersthereasonbearingismetalsclear,atbuttheprobablypolymerduetothehighatomicscatteringfactorofthePd(22)andends(formoredetails,seeExperimentalSectionTwo-dimensionalSupportingInformation).

controlledHOPGspacingsmecticlikewerealsoobservedassembliesinAFMoftheimagespolymerofpoly-chainswitha

D-1(+(23)that(24)Bates,determined(FigureS7).He,M.A.;Frenkel,bySR-SAXSTheaveragelayerspacing14nmisconsistentwith)onD.J.J.andChem.TEM.

Phys.1998,109,61931998S.-J.;,31,Lee,9387C.;-9389.

Gido,S.P.;Yu,S.M.;Tirrell,D.A.Macromolecules

-6199.J.AM.CHEM.SOC.

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VOL.130,NO.1,2008233

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