高分子物理復旦大學chapter5CondensedStatesofPolymers高分子的聚合狀態(tài)

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(玻璃化轉變)

tg:glasstransitiontemperature(玻璃化轉變溫度)glasstransitionasarelaxationprocess

thermalhistorydependenceoftgliquidvcrystalglass2glass11:fastcooling2:slowcoolingsupercooled

liquidttmtg1tg2temperaturedependenceofthespecificvolumeofpva,measuredduringheating.dilatometric(膨脹計法)resultsobtainedafteraquenchto–20c,followedby0.02or100hofstorage.(kovacs,a.j.fortschr.hochpolym.forsch.

1966,3,394)5.2polymercrystallizationrequisitesforpolymercrystallization

chemicalregularity

homopolymer

copolymer blockcopolymer randomcopolymer

stereoregularity(立構規(guī)整度)

isotactic(等規(guī))

syndiotactic(間規(guī))

atactic(無規(guī))5.2.1chainconformationsincrystals21314161525142=2162=

31717273929183813231h31helixconformationszig-zagconformationsh21hydrogenbondingsyndiotacticisotacticrepeatingunitwhyhelix?hh0.25nmpe0.12nmppch3:0.2nm

chainpackingincrystallatticeslhrhlhlhlhlhrhrhrh

chainpackingincrystallatticespeorthorhombictriclinichydrogenbondingtrigonali-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”areaggregatesofmanysinglecrystalslamellaecrystallizedfromdilutesolution

polyethylene(聚乙烯)tc~70ctc~80corientationsofpolymerchainsinlamellaepechainsmustbefoldedbackandforthwithinthelamella!note:thelamellarthicknessis~10nm,thechainlengthis>1000nm.pechainsareperpendiculartothelamellarsurface.

polyoxymethylene(聚甲醛)peo(聚氧乙烯)-b-ps(聚苯乙烯)diblockcopolymerlamellaecrystallizedfrommelt

spherulites(球晶)ofpolymersunderpolarizedopticalmicroscopy

lamellaeinaspherulitelamellaetiemoleculesamorphousthemechanismof

maltesecrossextinctionpatternop:polarizeroa:analyzerqe:vectorofpolarizedlighti0projectingonoatheoreticalanalysisof

maltesecrossextinctionpatternprojectingonoarelationsofpomandsals(smallanglelightscattering)pomsalssalspatternsofspherulitesvvhvqmax~1/r5.2.3polymercrystallizationhowdothepolymerchainspackinthelamellarcrystals?randomcoilwiththechaincontourlength(輪廓長度)longerthan1mmlamellawiththethicknessof5-50nmandlateralsizeofmicrons.crystallization

macroconformations(巨構象):extendedchains(伸展鏈)foldedchains(折疊鏈)randomcoils(無規(guī)線團)fringedmicelle(纓狀微束)chain-foldedlamellaeofpolymersrandomcoilcrystallizationtcordt

chainfolding(鏈折疊)conceptchain-foldedlamellaesefoldedchain(折疊鏈)foldsurface(折疊表面)slateralsurface(側表面)tc:crystallizationtemperature(結晶溫度)dt:supercooling(過冷度),dt=tm0-tc

se:foldsurfacefreeenergy(折疊表面自由能)s:lateralsurfacefreeenergy(側表面自由能),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

dgf

isthe

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

homogeneous(均相)andheterogeneous(異相)nucleationestimatethecriticalnucleussize

forprimarynucleus

forsecondarynucleus2.lineargrowthofpolymercrystallizationtemperaturedependenceoflineargrowthrate(線生長速度)temperaturedependenceoftheradialgrowthrateuofspherulitesinisotacticpolystyrene(left),polyamid6(center)andpoly(tetramethl-p-silpheylene

siloxane)(right).tf:equilibriummeltingtemperature.surfacenucleationonsubstratewithlengthlwitharateilineargrowthrateg:thegrowthrateofcrystalperpendiculartothesubstratel:foldlength;a:widthofstem;b:thicknessofthestem;g:substratecompletionrateoverallpolymercrystallizationrateoverallcrystallizationrate(總結晶速度)tm0tgtmaxoverallrate‘bell’curveofoverallcrystallizationratewc:weightfraction;vc:volumefractionw:weights:density(g/cm3):specificvolume(cm3/g)＝1/

definitionofcrystallinity(結晶度)wc

wc/wtotal;vcvc/vtotaltimecrystallinityisothermalcrystallizationt1t2t3t1/2iiiiiiivoverallcrystallizationkineticsavramiequationh0h￥1/2tt1/2lnththt’dilatometric(膨脹計法)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“l(fā)iquidcrystalsstandbetweentheisotropicliquidphaseandthestronglyorganizedsolidstate.lifestandsbetweencompletedisorder,whichisdeath,andcompleterigidity,whichisdeathagain.”

dervichiand.g.mol.cryst.liq.cryst.

1977,40,19.

statesofmatter:solids,liquids,andgases“l(fā)iquidcrystals”(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

layerstructureinsmecticphasessmecticasmecticctiltangledirectornlayersmoleculesliquidcrystalphaseofchiralmoleculesstructureofchiral

smecticorsmecticc*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*