高分子材料与应用(英文版)-Chapter-8-Functional-Polymers课件

高分子材料与应用（英文版）Chapter8FunctionalPolymers高分子材料与应用（英文版）Chapter8Functi18.1Introduction

8.1.1Definitionoffunctionalpolymers

Functionalpolymer——accordingtoIUPAC(a)apolymerbearingfunctionalgroups(suchashydroxyl,carboxyl,oraminogroups)thatmakethepolymerreactive,(b)apolymerperformingaspecificfunctionforwhichitisproducedandused.Apolymerthatexhibitsspecifiedchemicalreactivityorhasspecifiedphysical,biological,pharmacological,orotheruses

8.1Introduction

8.1.1Definit28.1.2Classificationoffunctionalpolymers

BiodegradablepolymerConductingpolymerElectroluminescentpolymerFerroelectricpolymerFerromagneticpolymerImpact-modifiedpolymerLiquid-crystallinepolymerMacroporouspolymerNon-linear-opticalpolymerOptically-activepolymerPhotoelasticpolymerPhotoluminescentpolymerPhotosensitivepolymer8.1.2Classificationoffuncti3PiezoelectricpolymerPolyelectrolytePolymersorbentPolymercompatibilizerPolymerdrugPolymergelPolymermembranePolymersolventPolymersupportPolymersurfactantResistpolymerShape-memorypolymerSuperabsorbentpolymerPiezoelectricpolymer48.1.3ApplicationsandoutlookoffunctionalpolymersApplications:Organiccatalysis(supportedcatalysts)Medicine(red-blood-cellsubstitutes)Optoelectronics(conductingpolymersMagneticpolymersandpolymersfornonlinearoptics)BiomaterialsPaintsandvarnishesBuildingmaterialsPhotographicmaterialsLubeandfueladditives8.1.3Applicationsandoutlook58.2Membrane

8.2.1Introduction

HistoryInitiatorofallcrossflowmembranetechnology——Dr.Sourirajan,removedsaltfromseawater,inthelate1950's.CommercialRO&UFmembranesoccurredintheearly1970’s.Crossflowmembraneprocessesbecamewellacceptedinindustryandmedicineinthe1980’s.Widelyusedtoday.Historyofmembrane8.2Membrane

8.2.1Introductio6Membrane——aselectivebarrierforseparatingcertainspeciesinafluidNophasechangePoresizes——determiningthesievedparticlesSeparation,concentration,fractionation&purificationCharactersMembrane——aselectivebarrie7MembraneconfigurationsMembraneconfigurations8Porousmembrane（多孔膜）

MF，UF，NFDensemembrane（致密膜）

ED，RO，GS，PV，VPClassificationofmembranesPorousmembrane（多孔膜）Classific9SymmetricmembraneAsymmetricmembraneStructureofporousmembranesSymmetricmembraneStructureof10Fig.5Schematicdiagramofa)asymmetricandb)anasymmetricmembraneFig.5Schematicdi11Schematicdiagramofthefiltrationbehaviorofa)anasymmetricandb)asymmetricmembrane

abSchematicdiagramofthefiltr12Classificationofmembranes——accordingtodrivingforceDrivingforceProcessesPressureMicrofiltration,Ultrafiltration,Nanofiltration,ReverseOsmosisElectricalpotentialElectrodialysisPartialpressurePervaporationConcentrationgradientDialysisClassificationClassificationofmembranesDri13Processofdead-endpressure-drivenmembranefiltrationClassificationProcessofdead-endpressure-d14Processofcross-flowpressure-drivenmembranefiltrationClassificationProcessofcross-flowpressure158.2.2CrossflowMembraneTechnologyFourcategories:Osmosis(RO)Nanofiltration(NF)Ultrafiltration(UF)Microfiltration(MF)

CrossflowMembraneTechnology8.2.2CrossflowMembraneTechn16Microfiltration(MF)Poresizes:0.05to3mTransmembranepressures(TMP):5~50psi(0.3~3.3bar)

Cross-flowvelocities:3~6m/sintubularmodules

Applications:

starch,bacteria,molds,yeastandemulsifiedoils

CrossflowMembraneTechnologyMicrofiltration(MF)Poresize17Ultrafiltration(UF)Poresizes:0.005to0.1mTransmembranepressures(TMP):

HigherthanMFCutoffmolecularweight:About1,000to500,000Concentratehighmolecularweightspecieswhileallowingdissolvedsaltsandlowermolecularweightmaterialstopassthroughthemembrane.CrossflowMembraneTechnologyUltrafiltration(UF)Poresize18Nanofiltration(NF)Poresizes:closetoonenanometerdiameter(10Å)Transmembranepressures(TMP):

HigherthanUFCutoffmolecularweight:200~300Application:WatersofteningCheese-wheydesaltingROpretreatmentPharmaceuticalconcentrationKidneydialysisunitsMaplesugarconcentration.CrossflowMembraneTechnologyNanofiltration(NF)Poresizes:19Reverseosmosis(RO)Poresizes:4to8ÅTransmembranepressures(TMP):

35~100atmCutoffmolecularweight:25and150Rejectionmechanism:"surface-force-poreflow"theory"solution-diffusion"theoryCrossflowMembraneTechnologyReverseosmosis(RO)Poresize20TypicalOperatingPressures-psig(bar*)RO-Seawater800~1000RO-WasteandProcess300~600RO-WaterPurification200~350RO-Undersink(Home)50NF100~200UF25~150MF(crossflow)10~25*14.5psig=1barCrossflowMembraneTechnologyTypicalOperatingPressures-21

Electrodialysis

Removalofionicspeciesfromnon-ionicproductsPervaporationSeparationofliquidmixturesbypartialvaporizationthroughapermselectivemembranePhasechangeoccursCrossflowMembraneTechnologyElectrodialysisCrossflowMem22

DialysisAconcentration-drivendiffusionApplication:Separationofproteinsandothermacromoleculesfromsaltsinpharmaceuticalandbiochemicalapplications,e.g.,hemodialysisCrossflowMembraneTechnologyDialysisCrossflowMembraneT238.2.3MembranematerialsMostofmembranesaremadeofpolymericmaterials,e.g.Polysulfone(PSF)Polyethersulfone(PES)Polyphenylsulfone(PPSU)PolyvinylideneFluoride(PVDF)Polypropylene(PP)Polyethylene(PE)CelluloseandCelluloseacetates(CA)Polyamide(PA)Polyacrylonitrile(PAN)Polytetrafluoroethylene(PTFE)8.2.3MembranematerialsMost24高分子材料与应用(英文版)-Chapter-8-Functional-Polymers课件25ROmembranematerialsCAmembranesToleratechlorineatlevelsusedformicrobialcontrolPAmembranesHigherrejectionandfluxTolerateawiderpHrangeSulfonatedPSFmembranesNFmembranematerialsPAmembranesCAmembranesROmembranematerials26UFmembranematerialsCAmembranesPVDFmembranesPSFmembranesTolerateapHrangeof0.5to13,temperaturesto85°C(185°F),and25mg/LoffreechlorineonacontinuousbasisMFmembranematerialsPAmembranesCAmembranesPVDFmembranesPC,PP,PE,PTFEUFmembranematerials27OperatingparametersforwidelyusedpolymericROandUFmembranes

ClassPolymertype

Max.

temp.

(psig)Max.

pressure

(psig)Optimum

pH

rangeMaxfreechlorine

continuous

(ppm)RO/NFcellulose

acetate(CA)4010002~82polyamide(PA)6510002~11NONEUF(CA)602002~93polysulfone(PS)1002000.5~1325vinylidene

fluoride(VF)802001~1250acrylonitrile(AN)802001~1050Operatingparametersforwidel288.2.4MembraneelementsCrossflowmembraneconfigurationcomparison

DesignCharacteristicSpiral-woundFibersTubularPlate&frameCostLowLowHighHighPackingdensityHighUF-High

ROVeryhighLowModeratePressurecapabilityHighUF-Low

RO-HighUF-Low

RO-MediumHighMembranepolymer

choicesManyFewFewManyFoulingresistanceFairUF-Good

RO-PoorVerygoodFairCleanabilityGoodUF-Verygood

RO-PoorVerygoodGood8.2.4MembraneelementsCrossf298.2.5MachinesandsystemsAsimplemachineformembranesystemsincludes:Apump——providethedrivingpressureandcrossflowvelocityHousingelementsConnectingplumbingControlvalve(s)PressuregaugesMotorcontrols8.2.5MachinesandsystemsAs30Membranesystemsoftenneedapretreatmentequipment——toreducemembranefoulingTheycanbeprecededorfollowedbyotherunitprocessessuchasdegasificationoractivatedcarbonadsorptione.g.,Forultrapurewaterapplications,two-passROsystemshavereplacedmanyRO-DIsystems.Membranesystemsoftenneeda318.2.6Designconsideration

——ImportantparametersAbalanceofflowandpressureHigher-pressurecauseshigherpermeate,alsocausesmoreseverefoulingHighercrossflowvelocityreducesfouling.8.2.6Designconsideration

——32Recovery——theratioofpermeatetofeedvolumeFeedwaterapplications:75~80%machinerecovery,SomeUFandROapplications:50~75%SeawaterDesalting™viaROistypicallyrunaslowas40%duetotheveryhighosmoticpressuregeneratedasthesaltinthefeedstreamisconcentrated.TemperatureThewarmerthefeedstreamthehigherthethroughputSolutionviscosityRecovery——theratioofperm338.2.7ApplicationsHundredsofapplications,fallinginthreebroadcategories:WaterpurificationManufacturingprocessseparationsWastetreatment.8.2.7ApplicationsHundredso34WaterPurificationBoilerfeedPotablefrombrackishoralkalinesourceColorremovalfromsurfacewaterMicrobialremoval;bacteria,pyrogens,giardiaandcryptosporidiumcystsTHMprecursorandpesticideremovalPotablefromseawaterSodiumandorganicsreductionforbeveragesReconstitutingfoodandjuicesBottledwaterCanandbottlerinsing

Applications:WaterPurificationWaterPurificationBoilerfee35RinsewaterformetalfinishingoperationsSpot-freecarwashrinsesLaboratoryandreagentgradewaterUSPPurifiedWaterandWaterforInjectionSemiconductorchiprinsingDistillationanddeionizationsystempretreatmentKidneydialysisMedicaldeviceandpackagingrinsewaterPhotographicrinsewaterPulpandpaperrinsesandmakeupwaterDyevatmakeupApplications:WaterPurificationRinsewaterformetalfinishi36ProcessJuiceandmilkconcentrationBeerandwinefinishingBeverageflavorenhancementCheesewheyfractionation/concentrationofproteinsandlactoseFoodoils,proteins,tasteagentsconcentrationSaccharidepurificationMaplesappreconcentrationEnzymesandaminoacids,purificationandconcentration

Applications:ProcessProcessJuiceandmilkconcen37ChemicaldewateringChemicalmixturesfractionationDyeandinkDesalting™GlycolandglycerinrecoveryEDpaint'srecoveryfromrinsesMedicineandvitaminconcentrationpurificationBloodfractionationCellbrothfractionationCellconcentrationPhotographicemulsionsconcentration/purificationApplications:ProcessChemicaldewateringApplicatio38WastetreatmentTertiarysewagewaterrecoveryHeavymetalsandplatingsaltsconcentrationBODandCODconcentrationDewateringliquidforreduceddisposalvolumeDilutematerialsrecoveryRadioactivematerialsrecovery

Applications:WastetreatmentWastetreatmentTertiarysew39TextilewasterecoveryforreusePulpandpaperwaterrecoveryforreuseDyeandinkconcentrationandrecoveryPhotographicwasteconcentrationandrecoveryOilfield"producedwater"treatmentLubricantsconcentrationforreuseCommerciallaundrywaterandheatreuseEndofpipetreatmentforwaterrecoveryApplications:WastetreatmentTextilewasterecoveryforre408.2.8RecentadvancesCompositemembranes——RO,UF&NFImprovedbothfluxandseparationIncreasechemicaldurabilityofmembranesSurfacetreatmenttechniquesAddingformalcharges——tochangeseparationabilityandreducefoulingtendency8.2.8RecentadvancesComposit41Enhancedsystemscontrols——improvedtheoperationalefficiencyIndustry'sevolvingrealization——treatmentsystemsareoftenmostefficientiftheycombineseveralunitprocesses.HomeROunitsEnhancedsystemscontrols——428.3AdsorptiveSeparationPolymers

8.3.1Introduction

Adsorption——preferentialpartitioningofsubstancesfromthegaseousorliquidphaseontothesurfaceofasolidsubstrate

Bonechar——decolorizationofsugarsolutionsandotherfoodsActivatedcarbon——removingnervegasesfromthebattlefield8.3AdsorptiveSeparationPoly43Adsorptionisdifferentfromabsorption——separationofasubstancefromonephaseaccompaniedbyitsaccumulationorconcentrationatthesurfaceofanother.

Adsorbent——theadsorbingphase.

Adsorbate——thematerialconcentratedoradsorbedatthesurfaceofadsorbent.Adsorptionisdifferentfrom44

Physicaladsorption——causedmainlybyvanderWaalsforcesandelectrostaticforcesbetweenadsorbatemoleculesandtheatomswhichcomposetheadsorbentsurface.Thusadsorbentsarecharacterizedfirstbysurfacepropertiessuchassurfaceareaandpolarity.Physicaladsorption——caused458.3AdsorptiveSeparationPolymers

8.3.1Introduction

Adsorption——preferentialpartitioningofsubstancesfromthegaseousorliquidphaseontothesurfaceofasolidsubstrate

Bonechar——decolorizationofsugarsolutionsandotherfoodsActivatedcarbon——removingnervegasesfromthebattlefield8.3AdsorptiveSeparationPoly46Adsorptionisdifferentfromabsorption——separationofasubstancefromonephaseaccompaniedbyitsaccumulationorconcentrationatthesurfaceofanother.

Adsorbent——theadsorbingphase.

Adsorbate——thematerialconcentratedoradsorbedatthesurfaceofadsorbent.Adsorptionisdifferentfrom47Absorption——aprocessinwhichmaterialtransferredfromonephasetoanother(e.g.liquid)interpenetratesthesecondphasetoforma“solution”.Theterm“sorption”isageneralexpressionencompassingbothprocessesofabsorptionandadsorption.Absorption——aprocessinwhi48

Physicaladsorption——causedmainlybyvanderWaalsforcesandelectrostaticforcesbetweenadsorbatemoleculesandtheatomswhichcomposetheadsorbentsurface.Thusadsorbentsarecharacterizedfirstbysurfacepropertiessuchassurfaceareaandpolarity.Physicaladsorption——caused49

ImportantindicesAlargespecificsurfaceareaAsuitableporesizedistributionSurfacepolarityPolaradsorbents:HydrophilicNonpolaradsorbents:HydrophobicImportantindices508.3.2Historicalbackground

ReferenceinBibleAristotle’sexperimentPracticeinancientEgypt,GraceandChina8.3.2HistoricalbackgroundR51PerhapsDr.GansinGermanywasthefirstpersonwhousedionexchanger(processednaturalzeolite)toanindustrialscale,basedonscientificunderstandingandtechnologicalmaturity.AdamsandHolmessynthesizedorganicionexchangerscalledionexchangeresinsin1935.PerhapsDr.GansinGermanyw528.3.3Classification

Ionexchangersaregenerallyinsolublesolidsorimmiscibleliquids(incaseofliquidionexchangers)capableofexchangingionswiththesurroundingsDependingupontheirabilityofexchangingcationsoranionstheionexchangersareeither'cation'or'anion'exchangersrespectively.8.3.3ClassificationIonexch53Acationexchangerconsistsofamatrixwithanegativecharge.Ananionexchangerconsistsofamatrixwithapositivecharge.Theoppositelychargedionscalled'counterions',compensatethematrixcharge.Acationexchangerconsistso54Onthebasisofthenatureofthematrixanionexchangermaybe'organic'or'inorganic'Inorganicresinsthematrixisahighlypolymerizedcrosslinkedhydrocarboncontainingionogenicgroups.Inorganicionexchangersaregenerallytheoxides,hydroxidesandinsolubleacidsaltsofpolyvalentmetals,heteropolyacidsaltsandinsolublemetalferrocyanides.Onthebasisofthenatureof55SyntheticInorganicIONExchangers

Themainemphasishasbeengiventothedevelopmentofnewmaterialspossessingchemicalstability,reproducibilityinionexchangebehaviorandselectivityforcertainmetalionsimportantfromanalyticalandenvironmentalpointofview.Syntheticinorganicionexchangersaregenerallyproducedasgelatinousprecipitatesbymixingrapidlytheelementsofgroups3,4,5and6oftheperiodictable,usuallyatroomtemperature.SyntheticInorganicIO56Organic-inorganicionExchangers

Traditionalorganicionexchangersarefoundtobeunsuitableathightemperaturesandunderstrongradiation.Inorganicionexchangersarereportedtobenotverymuchreproducibleinbehavior,andnotverystablemechanicallyandchemicallybecauseoftheirinorganicnature.Interesthasbeendevelopedtoobtainsomeorganicbasedinorganicionexchangers,i.e.,hybridionexchangers.Organic-inorganicion57Fibrousionexchangematerialscanbeusedintheformofvarioustextilegoodssuchascloth,conveyerbelts,nonwovenmaterials,staples,netsetc.consistofmonofilamentsofuniformsizerangingbetween5~50um.Thispredeterminesshortdiffusionpathofsorbentandhighrateofsorptionthatcanbeofabouthundredtimeshigherthanthatofthegranularresinswithaparticlediameterof0.25~1um,normallyused.Hasextremelyhighosmoticstabilitythatallowsthemtobeusedinconditionsofmultiplewettinganddryingoccurringatcyclicsorption/regenerationprocessesinairpurification.Fibrousionexchangematerial58e.g.,Anewclassofhighlycrosslinkedpolymericresins(Macronetresins)havebeendevelopedwithsurfaceareasashighas1200m2/g,whichapproachorexceedthoseofactivatedcarboninsomecases.Theseresinscanbeeasilyregeneratedinsituwithsimplealiphaticalcohols.TheMacronetresinsareavailableinarangeofdifferentfunctionalitiesandthuscanbeusedforselectiveremovalfrommulticomponentsystems.e.g.,598.3.4Adsorbents

Microporous,highspecificsurfacematerial(200~2000m2/g)Alumina(drying)Silicagel(drying)Zeolitemolecularsieves(gas&liquidseparations,drying)highlyspecific,singleporesizemaybefine-tuned:cations+structureAtypeorLTAXandYorFAUjasitesMordenite,othernaturalzeolitesSilicalitesorZSMx(hydrophobic,carbonlike)Activecarbon(gas&liquidseparations,guardbeds)Carbonmolecularsieves(narrowporedistribution)8.3.4AdsorbentsMicroporous,60

Others:impregnatedcarbons(Cu-chlorides-COseparation)clays(naturalandpillaredclays)resins,polymers(biological,ions,largemoleculesOthers:61离子交换树脂离子交换树脂是带有官能团(有交换离子的活性基团)、具有网状结构、不溶性的高分子化合物。通常是球形颗粒物。Ionexchangeresins离子交换树脂离子交换树脂是带有官能团(有交换离子的活性基团)62离子交换树脂的结构带有活性基团的网状高分子聚合物骨架活性基团丙烯酸树脂聚苯乙烯树脂交联剂酸性基团碱性基团—SO3H—COOH—N+R3OH-—NR2特殊基团CH2＝CH－COOCH3+离子交换树脂的结构带有活性基团的网状高分子聚合物骨架活性基团63聚苯乙烯磺酸型阳离子交换树脂聚合磺化交联剂交联作用活性基团R-SO3H+M+=R-SO3M+H+聚苯乙烯磺酸型阳离子交换树脂聚合磺化交联剂交联作用活性基团R64离子交换树脂的分类依据活性基团分类阳离子交换树脂阴离子交换树脂螯合树脂特殊交换树脂强酸型弱酸型交换基为酸性，H+与阳离子交换—SO3H—COOH—OHpH>2pH>6使用pH范围pH>10交换基为碱性，阴离子发生交换强碱型弱碱型—N+(CH3)3OH-—N+H3OH-—N+H2ROH-—N+HR2

OH-pH<12pH<4含有特殊螯合基团的树脂电子交换树脂，含有氧化还原功能基团手性基团，进行手性拆分R-NH2+

H2O

R-N+H3OH-

pH>pKapOH>pKb离子交换树脂的分类依据活性基团分类阳离子交换树脂阴离子交换树65交换反应阳离子交换树脂阴离子交换树脂R-SO3H+M+R-SO3M+H+RN+(CH3)3OH-

+X-RN+(CH3)3X-

+OH-R-NH2+H2OR-N+H3OH-

水合作用RN+H3OH-

+X-

RN+H3X-

+OH-螯合交换树脂R-L+M(R-L)nM交换反应阳离子交换树脂阴离子交换树脂R-SO3H+M+66离子交换树脂的性能参数交联度交换容量表征骨架性能的参数表征活性基团的性能参数是指交联剂在反应物中所占的质量分数交联度大，树脂孔隙，交换反应速度，选择性。小慢高交联度小，树脂孔隙，交换反应速度，选择性。大快低氨基酸的分离，交联度8%，多肽的分离2~4%每克干树脂所能交换的物质的量（mmol)。决定于网状结构中活性基团的数目。交换容量由实验测得离子交换树脂的性能参数交联度交换容量表征骨架性能的参数表征活67WatersofteningequipmentApplicationWatersofteningequipmentAppli68ContentsThedifferenttypesofliquidcrystalpolymers.Theimportanceofstructure-propertyrelationshipinpolymers.Synthesisofliquidcrystalpolymers.Applicationofliquidcrystalpolymers.PolymericLiquidCrystalsContentsPolymericLiquidCryst69MainChainLiquidCrystalPolymers(MCLCPs)MesogenicunitLinkingunitAgeneraltemplateformainchainliquidcrystalpolymersBasically,therearetwotypesofliquidcrystalpolymers;Mainchainliquidcrystalpolymers(MCLCPs)2.Sidechainliquidcrystalpolymers(SCLCPs)

MCLCPsconsistofrepeatingmesogenic(liquidcrystallike)monomerunits(seebelow).Themonomerunitmustbeaniostropicandbifunctional(onefunctionateachend)

toenablepolymeristaionandthegenerationofmesophases.Forexample,oneendofalong,lath-likemesogenicunitmightbeacarboxylicacidandotherendmightbeanamine;condensationwouldsequentiallylinkthemesogenicunittogethertogivealiquidcrystallinepoly(amide)MainChainLiquidCrystalPoly70ExamplesofMainChainPolymersg65N135IC98Dh118IMCLCPshaverepeatingmesogenicunits

FlexiblealternatinghydrocarbonspacersRacemicformDiscoticcoresofpolymerareseparatedbylongflexiblechainswhichagaingivethepolymerasufficientlylowmeltingpointformesogenicbehaviour.Inthiscase,asiscommonindiscoticsystems,ahexagonalcolumnarmesophaseisexhibited(confirmedbyX-ray)TheM.Wtofpolymer24,000.ExamplesofMainChainPolymer71SideChainLiquidCrystalPolymers(SCLCPs)AgeneraltemplateforsidechainliquidcrystalpolymersCalamiticmesogenicunitSpacerunitPolymerbackboneDiscoticmesogenicunitTerminallyAttachedLaterallyAttachedSeveralmethyleneunits,withesterorether(forattachment)SideChainLiquidCrystalPoly72ThirdClass:CombinedLiquidCrystalPolymersAgeneraltemplateforcombinedliquidcrystalpolymersThirdclassofliquidcrystalpolymersiscalledcombinedliquidcrystalpolymersThesepolymers,combinethefeaturesofMCLCPsandSCLCPs.Sidechainmesogenicunitscanbeattached,viaaspacerunit,toamesogenicmainchaineitheratthelinkingunitFigure-AoratthemesogenicunitFigure-BFigure-AFigure-BSidechainmesogenicuintsMainchainmesogenicuintsspacerLinkingunitThirdClass:CombinedLiquidC73TypesofSideChainLiquidCrystalsPolymersArangeofdifferenttypesofSCLCPsHomopolymersSidechaincopolymersBackBonecopolymersSC/BBcopolymersBB(backbone)e.g.,siloxanes,AcrylatesMethylacrylatesEthylenesEpoxidesMesogenicunitSpacerunitLinkingunitsbackboneTypesofSideChainLiquidCry74MesogenicUnitonMesomorphicBehaviourAtemplatestructureforpossiblemesogenicsidechainunitsTypicaltemplateforsomepossiblemesogenicunitscommonlyemployedinSCLCPs(mandnareusuallyoneortwo)MesogenicUnitonMesomorphic75FlexibleSpacersusedinSCLCPsEffectofspacerlengthonmesomorphicbehaviourTheinfluenceoftheflexiblespacerthatisnormallyessentialforthegenerationofmesophasesinSCLCPisofgreatinterest.Ingeneral,theincreasedorderinggeneratedonpolymerisationmeansthatsmecticphasespredominateandthenematicphaseisonlyexhibitedbypolymerswithashortspacerandashortterminalchain.FlexibleSpacersusedinSCLCP76InfluenceofSpacerLengthonMesomorphicPropertiesWherethepolymerswithoutspacerunitsexhibitliquidcrystallinephases,theyareofthesmectictype(a);

however,ashortspacerusuallygeneratesanematicphase(b)

Whichgiveswaytothesmecticphasesasthespacerlengthincreases(candd)MethacrylatepolymersInfluenceofSpacerLengthon77InfluenceofTerminalChainonMesomorphicPropertiesAcrylatepolymersR=terminalchainsn=spacerInfluenceofTerminalChainon78MesogenicSideChainUnitsg40SA121Ig30SA81I

g45SA93ICyanobiphenylunitshavecommonlybeenincorporatedintoSCLCPpolymersinordertogeneratepolymerswitha+vedielectricanisotropy.Polymers1-3differonlyintheunitwhichlinksthespacertothemesogenicunit.Polymer1hasaparticularlyhighclearingpointbecauseoftheenhancedpolarisability,whereasRemovaloftheetheroxygeninpolymer2hasreducedtheclearingpoint.Theclearingpointrecoversbytheuseofanesterlinkage3butnottothelevelofpolymer1becauseofthekinkinthestructure.Glasstransitiontemperature(Tg)relatestothepolarityoftheconnectingunit,highestforthepolaresterunit3andlowestforthehydrocarbonunit2123MesogenicSideChainUnitsg4079LengthofMesogenicUnitonMesomorphicPropertiesTheincreasedpolarisabilityandincreasedmolecularlengthingoingfromtwotofourphenylringsconsiderablyenhancestheclearingpointsofthesenematicpolymers.Thenematicphaseisprobablyexhibitedinpreferencetothesmecticphasebecausethespacerandterminalchainlengthsareshort.Polymerbecomemorecrystallineasthemesogenlengthincreases;againthisisexpected.LengthofMesogenicUnitonMe80PolymerBackboneonMesomorphicBehaviourCommon,non-mesogenicpolymersNaturalrubber:cis-2-Methylbuta-1,3-dieneSuperglue:methylα-cyanoacrylatealkenesMethylgroupandXcouldbethepointofmesogenicunitattachmentUnusualpolymerbackbonesthatbeenusedinSCLCPsPoly(phosphazenes)Poly(nitriles)PolymerBackboneonMesomorphi81PolymerBackboneonMesomorphicBehaviourCommon,non-mesogenicpolymersNylon6,6:ComposedofhexamethenediamineandadipicacidNaturalrubber:cis-2-Methylbuta-1,3-dieneSuperglue:methylα-cyanoacrylatealkenesPolymerBackboneonMesomorphi82BackboneFlexibilityonMesomorphicProperties123Thebackboneflexibilitydominatesforthreepolymers(1-3)withidenticalmesogenicsidechainsbutwithmethacrylate,acrylateandsiloxanebackbones,repectively.HereTgandTN-Ivaluesfallwithincreasingbackboneflexibility.BackboneFlexibilityonMesomo83SyntheticRoutestoPolymericMesogensThenatureofliquidcrystalspolymersmeansthattherearetwoaspectstothesynthesisFirstly,conventionalsynthesistoprovidethemonomerunits.Secondly,thepolymerisationreactionthatyieldthedesiredliquidcrystalspolymersSyntheticRoutestoPolymeric84Kevlar:NematicphaseheatKevlarKevlarexhibitsanamaticphasewhendissolvedinsulfuricacid,andextrusioninthenematicphaseprovidesthegreatstrength.Itiswell-knownpolymermaterialthatisextremelystrongandisusedinbullet-proofvestsinconstruction.DicarboxylicaciddiamineKevlar:NematicphaseheatKevla85MainChainLiquidCrystalsPolymer2000C2800CheatPoly(ethyleneterephthalate)DimethylterephthalateEthyleneglycolNewester4-hydroxybenzoicacid4-hydroxybenzoicacidunitsrandomlywithinthenewpolymerchaintogenerateaMCLCPSThispolymerpreparedbytransesterificationtransesterificationtransesterificationMainChainLiquidCrystalsPo86SiloxaneBackboneBasedLCPpo