Two- and Three-Dimensional Smectic Ordering of Single-Handed Helical Polymers(8)

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

SmecticOrderingofHelicalPolymers

Scheme

1

excessesofpoly-L-1(-)andpoly-L-1(+)wereestimatedtobe98.7and96.5%,respectively.18

FurtherAFMobservationsofthebundlestructuresofthepoly-L-1(-)onHOPGrevealeda2Dsmecticlikeself-assemblyofthepolymerchainswithacontrolledspacing(AandBofFigure4).Thelayerstructureisnearlyperpendiculartothedirectionofthepolymerchains.Theaveragelayerspacingofthe2Dsmecticlikeself-assembledpolymerchainsincreasedwiththeincreasingMworrodlengthofthepolymers:5.8,13,and28nmforpoly-L-1(+),poly-L-1(-),andpoly-L-1200(-),respectively(FigureS6).19Wenotethatthe2Dsmecticlikeself-assembliesofthepolymerchainssimultaneouslyguidethe1DarraysofthePtandPdmetalsbondedatthepolymerends,whichmayalsobeusedforfabricatingnanostructuredmaterials.Rodlikehelicalpoly-L-1’swithanarrowMWDappeartobeindispensableforthe2Dsmecticorderingonasubstrate.ConsiderablyclearlayeredimagesofsmecticLCsmallmol-eculesonsubstrateshavealsobeenobservedbyscanningtunnelingmicroscopy,butcontrollablelayerspacingsarelimitedtowithinafewnanometers.20

Polarizedopticalmicroscopyofaconcentratedsolutionofpoly-L-1(-)inchloroform(ca.15wt%)demonstratedthatthepolymerformsatypicalsmecticphase(smecticA)asevidencedbyitsindisputablyclearfan-shapedtexture(Figure4C).Acholesteric-smecticphasetransitioncouldbealsoobservedinaconcentrationgradient(Figure4D).Tothebestofourknowledge,thisisthefirstmicroscopicobservationofalyotropiccholesteric-smecticphasetransitionupondilutionofahelicalpolymerbasedonthemain-chainstiffness.Thedecisiveevidenceofthesmecticlayerstructurewasobtainedfromsynchrotronradiationsmall-angleX-raydiffraction(SR-SAXS)oforientedpoly-1filmspreparedfromaconcentratedsmecticLCchloroformsolutioninamagneticfield(11.75Tfor1day)byslowevaporation.21SR-SAXSofamagneticallyoriented

(18)In1thesameway,theLn,Lw/Ln,helicalsense,andhelicalpitchofpoly-L-200((19)images-)We(Figureandpoly-D-1(+)canbeestimatedfromthehigh-resolutionAFMpoly-preliminarilyS5).

molecular(amixturemeasuredofhigh-molecularhigh-resolutionAFMweightimagesoftheas-prepared

L-1Weweightpoly-poly-L-1(-)andlow-L-1(+))castfromasashownanticipatedinFigureaspontaneousS11,2Dsmecticlikediastereomericabenzenedomainformation.solutiononHowever,HOPG.seemsright-orleft-handedhelicalpoly-layereddomainscomposedofeitherL-1couldnotbeclearlyobserved.2Dsmecticlikelikelythatlayerthemolecularformation.lengthApparently,mayplayadominantroleinsuchIta(20)necessary(a)A.Hara,Ch.;NatureM.;toexplore1990Iwakabe,a,344,228Y.;possibleafurtherthoroughstudyis-Toguchi,spontaneousdomainformation.

230.(b)K.;Smith,Sasabe,D.H.;P.Garito,A.F.;Yamada,

S.;Garc DeBinnig,Schryver,G.ScienceF.C.Chem.1989,245Soc.,43Re-V.45.2003For,32reviews:E.;Ho¨rber,H.;Gerber,,139-150.(c)DeFeyter,Giancarlo,´a,L.;L.Amabilino,C.;Flynn,D.G.B.W.Chem.Acc.Chem.Soc.ReRes.V.20022000,,3133,(d)Pe´rez-,342491--356.501.

搜索“diyifanwen.net”或“第一范文网”即可找到本站免费阅读全部范文。收藏本站方便下次阅读，第一范文网，提供最新教学研究Two- and Three-Dimensional Smectic Ordering of Single-Handed Helical Polymers(8)全文阅读和word下载服务。