Chapter5CondensedStatesofPolymers5.1PolymerMeltsandGlasses5.2CrystallineStatesofPolymers5.3OrientedStatesofPolymers5.2.1ChainConformationsinCrystals5.2.2BasicMorphologyofPolymerCrystals5.2.3PolymerCrystallizationModels、Thermodynamics、Kinetics5.4LiquidCrystallinePolymers5.1PolymerMeltsandGlassesThedeepestandmostinterestingunsolvedprobleminsolidstatetheoryisprobablythetheoryofthenatureofglassandtheglasstransition.(Anderson,P.W.Science

1995,267,1615.)(liquid)liquidglasses(glasses)slowlycooledfastcooledTgfastslowTgGTThetransitionfrommelttoglassiscalledglasstransition(玻璃化轉(zhuǎn)變)

Tg:glasstransitiontemperature(玻璃化轉(zhuǎn)變溫度)GlassTransitionasaRelaxationProcess

ThermalhistorydependenceofTgliquidVcrystalglass2glass11:fastcooling2:slowcoolingsupercooledliquidTTmTg1Tg2TemperaturedependenceofthespecificvolumeofPVA,measuredduringheating.Dilatometric(膨脹計(jì)法)resultsobtainedafteraquenchto–20C,followedby0.02or100hofstorage.(Kovacs,A.J.Fortschr.Hochpolym.Forsch.

1966,3,394)5.2.1ChainConformationsinCrystals21314161525142=2162=

31717273929183813231H31HelixConformationsZig-zagConformationsH21HydrogenbondingsyndiotacticisotacticrepeatingunitWhyHelix?HH0.25nmPE0.12nmPPCH3:0.2nm

ChainpackingincrystallatticesLHRHLHLHLHLHRHRHRHtriclinicHydrogenbondingTrigonali-Poly-1-buteneMonoclinic5.2.2BasicMorphologyofPolymerCrystals

CrystalHabits:

a:lamellar

(薄片狀)b:platyc:tabulard:isometrice:prismaticf:acicularg:needle-like

h:fibrous

(纖維狀)“Singlecrystals”

haveonelatticeMacromolecularcrystalsareoftenlamellarorfibrous.“Polycrystallinesamples”areaggregatesofmanysinglecrystalsOrientationsofpolymerchainsinlamellaePEchainsmustbefoldedbackandforthwithinthelamella!Note:thelamellarthicknessis~10nm,thechainlengthis>1000nm.PEchainsareperpendiculartothelamellarsurface.

Polyoxymethylene(聚甲醛)PEO(聚氧乙烯)-b-PS(聚苯乙烯)diblockcopolymer

LamellaeinaspheruliteLamellaeTieMoleculesAmorphousThemechanismof

MaltesecrossextinctionpatternOP:PolarizerOA:AnalyzerQE:VectorofpolarizedlightI0projectingonOARelationsofPOMandSALS(smallanglelightscattering)POMSALSSALSpatternsofspherulitesVvHvqmax~1/R5.2.3PolymerCrystallizationHowdothepolymerchainspackinthelamellarcrystals?Randomcoilwiththechaincontourlength(輪廓長(zhǎng)度)longerthan1mmLamellawiththethicknessof5-50nmandlateralsizeofmicrons.Crystallization

Macroconformations(巨構(gòu)象):Extendedchains(伸展鏈)Foldedchains(折疊鏈)Randomcoils(無規(guī)線團(tuán))Fringedmicelle(纓狀微束)Chain-FoldedLamellaeofPolymersRandomcoilCrystallizationTCorDT

Chainfolding(鏈折疊)conceptChain-foldedLamellaeseFoldedchain(折疊鏈)Foldsurface(折疊表面)sLateralsurface(側(cè)表面)TC:crystallizationtemperature(結(jié)晶溫度)DT:supercooling(過冷度),DT=Tm0-TC

se:foldsurfacefreeenergy(折疊表面自由能)s:lateralsurfacefreeenergy(側(cè)表面自由能),se10slLamellarthicknessorfoldlength(片晶厚度)ProcessofPolymerCrystallization

Twosteps:

1.Nucleation(成核)processSizeDG0embryosupercritic.sizestablecriticalnucleusDG=Gcrystal–Gmelt,DG=DH–TDSGcrystal=Gbulk+SAsDG=Gbulk-Gmelt

+SAs

=DGf+SAsA

isthesufaceareaand

DGfisthe

bulkfreeenergychange.abcSchematicrepresentationofthechangeinfreeenergyasafunctionofsizeillustratingthenucleationprocessTypesofcrystalnuclei.(a)primary(初次),(b)secondary(二次),(c)tertiary(三次)nucleus.

Homogeneous(均相)andheterogeneous(異相)nucleationOverallPolymerCrystallizationRateOverallcrystallizationrate(總結(jié)晶速度)Tm0TgTMAXOverallrate‘Bell’curveofoverallcrystallizationratewc:weightfraction;vc:volumefractionW:weights:density(g/cm3):specificvolume(cm3/g)＝1/

Definitionofcrystallinity(結(jié)晶度)wc

Wc/Wtotal;vcVc/VtotalTimeCrystallinityIsothermalcrystallizationT1T2T3t1/2IIIIIIIVOverallCrystallizationKineticsAvramiequationh0h￥1/2tt1/2lnththt’Dilatometric(膨脹計(jì)法)Kineticsmodelsofoverallcrystallization1.FreegrowthmodelR~vtb.newnucleusproduced-

homogeneousa.constantnumbersofnucleus-

heterogeneoust+DttDttI*nucleationratetPoisson’sraindropproblemIfraindropsfallrandomlyonapondcreatingexpandingcircularwaves,whatisthechancethatthenumberofwavescreatedbydifferentraindropswhichpassoverarepresentativepointPuptotimetisexactlyn?Kineticsmodelsofoverallcrystallization-Avrami2.ImpingementmodelPPoissondistributionWhatisthechancethatnowavereachesagivenpointPinspace?heterogeneoushomogeneousTheAvramiequationfor3DE(t):wavespreadingareaduringtWhiletorvisverysmallorThermodynamicsofCrystallization:

1.MeltingpointofLamellarCrystalsThermodynamicsofCrystallization:

1.MeltingpointofLamellarCrystalsMeltingdataforlamellarpolyethylenegrownfromthemeltandfromsolutionTm=414.2(1-0.627/l)Lauritzen-HoffmanequationSimilartocriticalnucleussizeGibbs-ThomsonextrapolationlaThermodynamicsofCrystallization:

2.MeltingpointofPolymermixtureChemicalPotentialofPolymerinamorphousphaseConsiderasystemofPolymer/Impuritymixture:ChemicalPotentialofonemonomerunitofpolymerinamorphousphasePolymeriscompatiblewithimpuritybutcan’tco-crystallizewithimpurityEffectsof“Impurities”onTmConditionofPhaseEquilibriumSuperscriptofC:CrystallinePhaseSuperscriptofI:AmorphousPhaseEffectsof“Impurities”onTmForx2,x1=1Forend-groupeffects:1=2/N,=0Forcopolymeralternatingcopolymer:P<<XARandomcopolmer:P=XABlockCopolymer:P>>XA1P:ProbabilityofcrystallineunitwithsequentialconnectionNote:Forpolymerblendspolymer/smallmoleculepolymer/polymer3.EffectsofChainStructureonTm1)SymmetryandAsymmetry2)FlexibleandRigid3)MolecularInteraction5.3OrientedStatesofPolymersDefinition

ApplicationsFiber,BOPP,BOPET,BOPE,…Orientationfunctionq<cosq><cos2q>fullyorientedfullydisorder10perpendicular011/30F10-1/2q:0~180°oneortwodimensionalorder5.4LiquidCrystallinePolymers“Liquidcrystalsstandbetweentheisotropicliquidphaseandthestronglyorganizedsolidstate.Lifestandsbetweencompletedisorder,whichisdeath,andcompleterigidity,whichisdeathagain.”

DervichianD.G.Mol.Cryst.Liq.Cryst.

1977,40,19.

Statesofmatter:Solids,liquids,andgases“Liquidcrystals”(LCs)representanumberofdifferentstatesofmatterinwhichthedegreeofmolecularorderliesintermediatebetweentheperfectlong-rangepositionalandorientationalorderfoundincrystallinesolidandthestatisticallong-rangedisorderfoundinanisotropicliquid.Phenomenologically,LCsexhibitbothsolid-likeanisotropicfeaturesandliquid-likefluidity.Onthebasisofthesecharacteristics,theterm“mesomorphicphases”or“mesophases”,maybeamoreappropriatenamethanliquidcrystals.WhatareLiquidCrystalsAnisotropicmolecularshapeofliquidcrystalsRod-likeorellipsoid-likeSpacefillingmodelofmolecule7S5Plate-likeordisk-like

Lyotropicliquidcrystals(溶致型液晶):Theliquidcrystalphaseisdependentontheconcentrationofonecomponentinanother.

Thermotropicliquidcrystals(熱致型液晶):Theliquidcrystalphasesofpuresubstancearecausedbytemperaturechange.NematicPhase(向列相)DirectorNLong-rangeorientationalorderofmoleculesMoleculesNnnnnnnn

MoleculararrangementinanematicphasePolydomainstructureinanematicphase.Localdirectorsarerepresentedbyn,andtheglobaldirectorisrepresentedbyN.SmecticPhases(近晶相)DirectorNLayersMolecules

LayerstructureinsmecticphasesSmecticASmecticCTiltAngleDirectorNLayersMoleculesLiquidCrystalPhaseofChiralMoleculesStructureofchiralsmecticorsmecticC*phase.Theplanesrepresentthesmecticlayers.Thedirectoralwaysmakesthesameanglewiththesmecticplanes,buttheorientationofthedirectorrotatesaboutthelineperpendiculartotheplanesingoingfromonelayertothenext.Cholestericphase(膽甾相)(chiral(手性)nematicphase)

Chiral

smecticphaseMoleculesinthecholestericphase.Thedirectornrotatesinahelicalfashion.Becausenophysicalquantitiesdependonthesignofn,thephysicalpitchofthecholestericphaseisP=p/k0ratherthan2p/k0.Cholesterolnonanoatemolecule:Lyotropicliquidcrystals:

1)surfactantsoramphiphilicblockcopolymersLyotropicliquidcrystals:

2)rigid-rodpolymershCc2*~M-1c1*c2*c1*~M-2POMUsedintheStudyofLCPhasesFordifferentLCphases,thetextures(織構(gòu))underPOMaredifferentNem