《聚合物合成與改性技術(shù)》 教學(xué)大綱(英文版)

‘PolymerSynthesisandModificationTechnology’CourseSyllabusCourseCode：09040003CourseCategory：MajorSelectiveMajors：IntensiveTrainingClassSemester：SpringTotalHours：36Hours Credit：2LectureHours：36Hours LabHours：0 PracticeHours：0PolymerChemistry,H.R.Allcock,F.W.Lampe,J.E.Mark,ChemicalIndustryPress2006,ISBN:7502576444.References：PolymerScienceandTechnology,J.R.Fried,ChemicalIndustryPress2005,7502568255.PrinciplesofPolymerChemistry,A.Ravve,ChemicalIndustryPress2008,9787122009845.Newtechniquesofpolymersynthesis(thesecondedition),editor:JianguoWang,ChemicalIndustryPress2004,ISBN:7502553150.Polymermodification,editors:YaguangQiandXumingXue,ChemicalIndustryPress2005，ISBN:7502563237/G.1618.Synthetictechniqueofpolymers,DerenZhao,WeishengZhang,ChemicalIndustryPressISBN:7502516816.Engineeringplasticsbyblendingmodification,RushengDeng,ChemicalIndustryPressISBN:750254416x.Polymermodification,GuoquanWang,XiufengWang,ChinaLightIndustryPress2008,ISBN:9787501963621.Principlesandapplicationsofpolymerblendingmodification,GuoquanWang,ChinaIndustryPress2007,9787501957415.PMMAresinsandtheirapplications,ZhanbiaoMa,ChemicalIndustryPress2002,7502533885.TeachingAim：PolymersynthesisandmodificationtechnologyisamajorselectivecourseinCollegeofChemistry,ChemicalEngineeringandMaterialsScienceattheSoochowUniversity.Itcanbealsoregardedasaspecialandbasiccourseforstudentsindifferentspecialties.Bytakingthiscourse,thestudentscanmasterthebasicconcepts,theoriesandmethodsofpolymersynthesisandprocessingandwillunderstandthecharacteristicsofdifferentkindsofpolymers.Polymerchemistryisaimedatsynthesisandreactionofpolymers,andpolymer modificationunderlieswideuseofpolymericmaterials,sobothofthemareveryimportanttoeachother.Thiscoursewillbefocusedona)basictheoryofpolymerreactions,b)relationshipsamongreactiontheory,structures,propertiesandapplications,andc)basictechnologyofpolymermodificationpreparation.Thestudentsareexpectedtomasterthefollowingcontentsafterattendingthiscourse:tounderstandsomebasicconceptssuchaspolymerizationrate,averagedegreepolymerization,macromolecularmicrostructureandcopolymercompositionandsomeimportantreagentssuchasmonomer,initiator,catalyst,chaintransferagent,inhibitor,emulsifieranddispersant;2)tolearnbasicpolymerizationmethodssuchasnormaland “l(fā)iving”/controlledfreeradicalpolymerization,step-growthpolymerization,andionicpolymerization;3)toclassificationoftopologicalpolymersincludingdendrimersandtheirself-assembly;4)tomasterbasictheoryandmethodsofpolymermodification,moldingandproduction.Aftertakingthiscourse,thestudentswilllearnhowtosynthesizepolymersfromtherawmaterials,canunderthedifferentcharacteristicsofvariouspolymericmaterialsandcanhandlethemodificationprocessofcommonpolymers.Thestudentscanalsobecapabletosolvetheengineeringproblemsandcanmakeupthegapbetweenthetheoreticalknowledgeofpolymerchemistryandpracticalproduction.Tostudythepresentcourse,thestudentshadbetterpossessthebasicknowledgeofdifferentialcourses,suchaspolymerstructureandproperties,polymerchemistry,polymerphysicsandmaterialsscienceandengineering.Thestudentsshouldalsohavethebasicunderstandingsofmechanicsandengineering.Thecoursewillbeveryusefulfortheirfurtherstudiesandfutureemployment.ChapterOne FreeradicalpolymerizationHours：twoweeks，4hoursintotalContentsChainpolymerizationfamilyClassifiedbythenatureofreactivecenter:radicalpolymerization,cationicpolymerization,anionicpolymerization,coordinatingionicpolymerization.Chainpolymerizationconsistsofasequenceofthreesteps:Initiationreaction,Propagationreaction,Terminationreaction.Examplesonpolymerspreparedviafreeradicalpolymerization.MechanismofradicalpolymerizationGeneration of free radicals: thermal decomposition, photochemical oxidation-reduction(redox)reaction,highenergyparticleradiation.Theactivityofafreeradicalisdeterminedbyitsstructure.Reactionsofthefreeradical:additionreaction,couplingreaction,disproportionationreaction,dissociationreaction,andtransferreaction.MonomerstructureandtypesofpolymerizationMostofthemonoolefin,conjugateddiolefin,alkyneandcarbonylcompounds,andsomeoftheheterocycliccompoundscanbepolymerizedfromthethermodynamicviewpoint.However,theselectivityofvariousmonomerstodifferentpolymerizationmechanismsvariesgreatlyanddependsonsomefactorssuchastheelectroniceffectofthesubstituentsinvolvingtheinductiveorresonanceeffectandstericeffect.ElementaryreactionsoftheradicalpolymerizationTheynormallyrefertochaininitiation,chainpropagation,andchaintermination.Perhapsthepolymerizationisaccompaniedbychaintransferreactionandsoon.CharacteristicsoftheradicalpolymerizationTherateofinitiationisthelowestone,whichcontrolstheoverallrateofpolymerization.Inconclusion,thecharacteristicsofradicalpolymerizationareslowinitiation,fastpropagation,fasttermination,andeasytransfer.InitiatorsandinitiationTypesofinitiators:azoinitiator,organicperoxideinitiator,inorganicperoxideinitiator,initiationsystem.Kineticsofinitiatordecomposition:initiatordecompositionrate,initiatorefficiency,andchoiceinitiator.Otherinitiationsystems:thermal-initiatedpolymerization,lightinitiatedpolymerization,andenergyradiationinitiatedpolymerization.RateofradicalpolymerizationPolymerizationrateandmeasuringmethod,steady-statepolymerizationrateequation,effectoftemperatureonpolymerizationrate,rateconstantsofelementaryreactionandmainparameter,autoacceleration,typesofratechangingduringthepolymerizationprocess,inhibitionandretardation.MolecularweightandchaintransferreactionMolecularweightisanimportantparametertocharacterizepolymers.Factorsaffecttherateofpolymerization,suchastheconcentrationofinitiators,theconcentrationofmonomers,thepolymerizationtemperature,andsoon,whichalsoaffectthemolecularweight.Chaintransferreactionusuallydoesn’taffecttherateofthepolymerization,however,affectsthemolecularweightverymuch.Molecularweightisalsoanimportantpartinkineticsstudy.Kineticchainlengthandthedegreeofpolymerization.Problems:Whataremolecularweightandpolydispersityofpolymers?Pleaselisttherepeatingunitofthefollowingpolymersandmonomerstosynthesizethem:PSt,PMMA,PAA,PVA,PIP,PTFE.Pleaselisttheresourcestogeneratefreeradicals.4Pleaselistmainreactionsofradicals.Pleaselistthreemonomerswhichcanbepolymerizedviaradical,ionicandcoordinationpolymerizations.Can1,1-diphenylethylenebesubjectedtopolymerization?Why?Pleasedrawchemicalstructuresofpoly(styrene-alt-maleicanhydride).8Pleaselistelementalreactionsofchainpolymerization.Pleaselistthetypesofmicrostructuresformonosubstitutedvinylmonomers.Pleaselistthetypesofchaintransferreactioninfreeradicalpolymerizationandgiveexamplesofchaintransferagents.Whatarethecharacteristicsofradicalpolymerization?Notions:efficiencyofinitiation,kineticchainlength,autoacceleration(geleffect),radicalpolymerizationrate,inhibition,retardationChemicalstructures:AIBN,BPO,KPS,cumylhydroperoxidePleaselisttherelationshipbetweendegreeofpolymerizationandkineticchainlength.15Pleaseexplainbasicprinciplesofdilatometermethod.ChapterTwo “Living”/controlledradicalpolymerizationHours：twoweeks，4hoursintotalContentsLivingandcontrolledsystemsLivingsystems:constantnumberofpolymerchains,nopermanentchainstoppingreactions,ndormantandactivestate,controlofchain-growth,narrowMWD(Poisson),Mvs.monomernconversionislinear.Controlledsystems:sidereactionsdooccur,howeverstillhaveacontroloverendgroups,topology,monomersequence.LivingpolymerizationLivingpolymerizationisaformofadditionpolymerizationwheretheabilityofagrowingpolymerchaintoterminatehasbeenremoved.Chainterminationandchaintransferreactionsareabsent,andtherateofchaininitiationismuchlargerthantherateofchainpropagation.Theresultisthatthepolymerchainsgrowatamoreconstantratethanseenintraditionalchainpolymerizationandtheirlengthsremainverysimilar.Livingpolymerizationisapopularmethodforsynthesizingblockcopolymerssincethepolymercanbesynthesizedinstages,eachstagecontainingadifferentmonomer.Additionaladvantagesarepredeterminedmolecularweightandcontroloverendgroups.TypesoflivingpolymerizationsLivinganionic/cationicpolymerizationRing-openingmethathesispolymerization“Living”/controlledfreeradicalpolymerizationGrouptransferpolymerizationLivingZiegler-NattapolymerizationHowtorealizealivingsystem?Reversibleactivation,chaintransferprocesses,andcombinationofIonicpolymerization:Easydesignofpolymericarchitectures:Veryselectivereactions,requiresextremereactionconditionssuchaslowtemperaturesandhighpuritysolventsandreagents,expensivetoundertakeforindustry(catalystscost,variousrequirements).Freeradicalpolymerization:Goodtolerancetowardsimpurities,widerangeof(functionalized)monomers,widelyemployedinindustryviabulk,solution,emulsion/suspensionpolymerization,inhibitionbyoxygen,andlackofselectivereactions.InifertermethodDevelopedbyOtsuinThermal-initiatediniferter: Most of them belong to derivativesof 1,2-disubstitutedtetraphenylethanesPhoto-initiatediniferter:CompoundscomprisingdiethyldithiocarbamateCatalyticchaintransferpolymerization(CCTP)Certainlow-spincobaltcomplexes,typical[Mon]/[Co]ratioofca.106NitroxidemediatedlivingradicalpolymerizationTypicalnitrooxyradicalis2,2,6,6-tetramethylpiperidinyl-1-oxy(TEMPO)Hightemperatureisrequired(>110oC),andtherearelimitednumberofmonomersTransitionmetalmediatedlivingradicalpolymerization(Atomtransferradicalpolymerization,ATRP)ATRPprocessusingCuBr/bpycatalyticsystemApplicationofATRP:Topreparewell-definedmacromoleculeswithpredeterminedMWandloww/nnpolydispersity(1.04<MM<1.50,300<M<200,000),tocontrolmacromoleculararchitecture,w/nntocontrolmicrostructureofmacromolecules,andtopreparemacromonomersandfunctionalizedpolymerswithCOOH,OH,andvinylgroups.Reversibleaddition-fragmentationchaintransfer(RAFT)polymerizationControloverMW&architectureWiderangeofmonomersAmbientreactionconditionsOne-stepprocessSimplepurificationofproductRAFTagents:onlyafewagentsareavailablecommercially(expensive!!)Thio-chemistry:hazardousandsmellyApplicationofRAFTprocessProblems:Whatarebasicfeaturesoflivingpolymerizationsystems?Pleaselistthemaintypesof“l(fā)iving”/controlledradicalpolymerization.3PleaselistthebasicmechanismandapplicationofATRP.4PleaselistthebasicmechanismandapplicationofRAFTpolymerization,anddescribeprimaryrolesofZandRgroupsofRAFTagent.ChapterThree IonicpolymerizationHours：twoweeks，4hoursinContentsOverviewSomemonomers,likealkenesandsubstanceswithrings,canundertakeionicchainpolymerizationwithanionicinitiator.Accordingtothesortsoftheactivecenterattheendoflongchain,ionicpolymerizationcanbeclassifiedintothreecategories:cationic,anionicandcoordination.Theactivecenterofcationicpolymerizationisacarbocation,andtheactivecenterofcationicpolymerizationisacarbocation.CationicPolymerizationInitiatorandmonomerAlkeneswithelectron-donatingsubstituentsarecationicpolymerizableAcationiccatalystorinitiatorcouldreactwiththeabove-mentionedmonomertoproducecarbocationicactivecenter.Thecationicinitiatorscanbeclassifiedintotwocategories:strongprotonacidandLewisacid.Cationicpolymerizationmechanism:Cationicpolymerizationbelongstochainpolymerization,anditcontainsinitiation,propagation,transfer,andtermination.Thefeatureofthecationicpolymerizationisfastinitiation,rapidpropagation,veryextremelyeasytransferandcomparativelyhardtotermination,inwhichaterminatorisoftenindispensable.ReactionkineticsPolymerizationInitiatorandTypicalanionicpolymerizablemonomers:styrene,MMAandacrylicnitrileetc.Alltypesofmonomersare-conjugatedsystemorthatwithelectronattractinggroup,makingthedensityofelectroncloudofdoublebonddeclineTheanionicactivecenterreactswithdoublebondbyadditionreactionMechanism:Theanionicpolymerizationstillbelongstothechainpolymerization.Itconsistsof3elementaryreactions:initiation,propagation,andtermination.Livingpolymer:Aslongasnoterminationoccurs,thoughallmonomersareusedup,thepolymerstillremainsactivity.Whennewmonomerisadded,thepolymerizationrestarts.Whenanotherkindmonomerisadded,ablockcopolymerproduces.Manyinitiatorscanbeusedinthelivingpolymerization.ThemostconvenientismetalNaandnaphthalenenatriuminitiator.AlkalimetalNatransferstheelectronoftheouterlayertothemonomer,toformamonomeranionradical,whichisproduced,throughtheradicaldouble-grouptermination,doubleaniontotakeonthelivingpolymerization.ReactionkineticsApplication:Tosynthesizemonodispersepolymers,tomeasuretheanionicpolymerizationrateconstant,toprepareblockcopolymers,andtopreparetelechelicpolymers.Comparisonbetweenradical&ionicpolymerizationsMonomerandinitiatorMechanismKineticsTemperatureEffectofsolventandotherchemicalsProblems:TakeNa-naphthalenebasedanionicpolymerizationofstyreneforexample,pleasedescribethebasicmechanismandapplicationoflivinganionicpolymerization.Howaboutthebetweenpolymerizationdegreeandkineticchainlength?Pleasedescribethemainapplicationsoflivinganionicpolymerization.Pleasecomparethesimilarityanddifferencesamonganionicpolymerization,cationicpolymerizationandfreeradicalpolymerization.ChapterFour DendrimerandhyperbranchedHours：threeweeks，6hoursintotalContentsOverviewofdendriticpolymersDendriticpolymersarehighlybranchedpolymerstructures,withcomplexsecondaryarchitecturesandwell-definedspatiallocationoffunctionalgroups.Theycanbeusedinapplicationssuchastargeteddrug-delivery,asmacromolecularcarriers,forcatalysis,assensors,forlightharvesting,forsurfaceengineering,asbiomimeticmaterials.Dendriticpolymersexhibitverydifferentpropertiescomparedtotheirlinearanalogues.Dendriticmaterialssub-classes:dendrimers,dendrons,hyperbranchedpolymers,dendrigraftpolymers,dendronizedpolymers.DendrimersWhendendriticpolymersareperfectlybranchedtheyareeitherdendronsordendrimers.Thedendrimerscompriseasinglecorethatiscappedwithlayersofrepeatunitswhichareradiallybranched.Eachlayeriscalledageneration.Muchlikeproteinsandnaturalproducts,dendrimersarenearmonodispersewithpredictablemolecularweightsandnano-scaledimensions.Theuniquepropertiesofdendrimersareattributedtotheirglobularstructure,resultinginternalstructuresinwhichallbondsemergeradiallyfromacentralcore,andalargenumberofend-groupsarepresentatitssurface.Dendrimersconsistofaseriesofchemicalshellsbuiltonasmallcoremolecule.Eachconsistsoftwochemicals,alwaysinthesameorderandiscalledageneration.Dendrons:Dendronsrepresentastructuralcomponentoftheparentdendrimer,andaremonodisperse,wedged-shapedsectionsofadendrimer.Examplesofdendrimers:Tomalia-typepoly(amidoamine)(PAMAM)Fréchet-typepoly(benzylether)Newkome’sarboroldendrimersPhosphorus-containingdendrimersPoly(2,2-bis(hydroxymethyl)propionicacid)dendrimerDendrimersynthesisDivergentsynthesis-Multiplicativegrowthfromacentralcore.Convergentsynthesis-Preparationstartingfromwhatwillbecometheperipheryofthemoleculeandprogressinginward.DendrigraftpolymersDendrigraftpolymers,sometimesreferredtoasarborescentpolymers,arearelativelynewadditiontothedendriticfamily,combiningfeaturesofdendrimersandhyperbranchedpolymerswithlinearpolymers.Dendrigraftpolymersaregrowningenerations,muchlikedendrimers,buttherepeatingunitisanoligomerorapolymerchain,ratherthanasmallmonomerunit.Asdendrigraftpolymersflexiblepolymerswithveryhighmolecularweightsareobtainedrapidly.Examplesofdendrigraftpolymersare:Comb-bursts,arborescentpolybutadiene.DendronizedpolymersDendronizedpolymers,sometimestermed“rod-shapedpolymers”,arestructureshavingalinearbackbonewithdendriticsidechains.Dendronizedpolymersareasub-classofcomb-polymerswherethe“comb’steeth”aredendronsinsteadoflinearpolymerchains.Dependingonthedensityandsizeoftheattacheddendrons,thedendronizedpolymerscanhaveeitherrandomcoilorfullystretchedoutconformation.Fullystretchedoutdendronizedpolymersarerod-likecylindricalpolymers(nanotubes)andarebelievedtohavenewandinterestingproperties,sincetheyhavedimensionsreminiscentofseveralbiologicalfunctionalunits,suchasthemosaicvirus(lengthsupto400nmanddiametersupto6nm)HybridstructuresPolymerscontainingbothlinearchainsanddendriticpartsareoftenreferredtoas“dendritic–linearpolymerhybrids”orjust“hybridmaterials”.Oneapproachtoobtainhybridstructuresisbyturningthecoreorthemultipleend-groupsofthedendriticpolymerintoinitiatingmoietiesforpolymerization.Anothermethodutilizesagrafting-tostrategy,inwhichpre-formedpolymerlinearchainscoupledtoadendriticcore.HyperbranchedpolymerGeneralmethodtosynthesizehyperbranchedpolymer:ABnmonomer,AB*Otherroutes:inimer-basedSCVPviaNMP,ATRPandRAFT,Ax+By(ormoremonomers)typecondensationoradductivepolymerizationApplicationsofdendrimersSuprachemistry,catalyst,biomedicine,optics,andotherfields.Problems:1Pleasedescribemainsubclassesofdendriticpolymers.2Whatisdendrimer?Howaboutitsmainapplications?Pleaselistthreetypesofdendrimers?WhatistherepeatingunitofTomalia-typepoly(amidoamine)dendrimer?Pleaselistthemainmethodstosynthesizedendrimers?Byassumingthecorefunctionalityism,andeachbranchingpointhasthreelinkingpositions,pleasecalculatethesurfacefunctionalityofdendrimerwithgenerationn.Pleasedescribetheadvantageofsynthesisofdendrimersviaorthogonalstrategy.Pleasedescribethesimilarityanddifferenceofdendrimerandhyperbranchedpolymer.Howtocalculatethedegreeofbranching?ChapterFive Polymerself-assemblyHours：threeweeks，6hoursinContentsOverviewPhasediagramofadiblockcopolymerTriblockcopolymers:EvenmoreoptionsPolymerandnanostructureSupramolecularchemistry:Toconstructpolymermaterialsvianon-covalentbondssuchhydrogenbond,ionicbondandcoordinationbond.Polymerself-assembly:Hollowpolymersphere,polymertube,molecularwire,moleculardeviceNanostructure:SuprahydrophobicmaterialsWhatissupramolecularchemistrySupramolecularchemistryisthechemistryoftheintermolecularbond,concerningthestructureandfunctionsoftheentitiesformedbytheassociationoftwoormorechemicalspecies.(Jean-MarieLehn)MolecularChemistry:covalent,ionicandmetal-metalbonds-IntramolecularbondingSupramolecularchemistry:chargegroups,dipoles,H-bonds,hydrophobic/hydrophilicinteractions,-interactions,non-bondingelectronicrepulsion-IntermolecularbondingMolecularaggregates:heldtogetherbyintermolecularforcesMajorintermolecularforces:non-directional:vanderWaalsdirectional:H-bonds,-interactionsStrength:Intermolecularforces–––usuallylessthan10Distance:0.3-0.5nmMakingnanostructures:nanomanufacturing“Topdown”versus“bottomup”methodsWhatdrivesself-assembly?Staticassembly(thermodynamicfreeenergyminimum)-onceformeditisstableDynamicassembly(kineticallyformed,notnecessarilythermodynamicminimum)-notnecessarilystableForcesofchemicalbonding(4):covalent,ionic,vanderWaals,hydrogenOtherforces(magnetic,electrostatic,fluidic)Polar/Nonpolar(hydrophobicity)Shape(configurational)Templates(guidedself-assembly)Kineticconditions(e.g.,diffusionlimited)TypicalaggregatesLangmuirFilmofanamphiphilicmoleculeLangmuir-BlodgettFilmSAM:SelfassembledmonolayerSelf-assemblywithdiblockcopolymersCharacteristicsofsoftmatterLengthscales:Structuresof≈10-1000nmdeterminethepropertiesTimescales:processesfrom-103sDynamicsprocessesoverawidetimescales-103sVeryslowprocessesinnon-equilibriumconfigurationsWeakinteractionsInteractionsbetweenmoleculesandmolecularstructures≈kTSelf-assemblyHierarchicalarrangementofstructuresCompetitionbetweeninteractionenergyandentropySurfactantsandamphiphilesShapeofaggregatesBasicshapes:spheres,cylinders,bilayers,vesiclesSuperstructures:micellarcrystals,lamellarphases,bicontinuousnetworksSuprastructuresfromsurfactantsMicelles:sphere,rodlikeVesiclesComplexstructures:LBfilmandmultilayermembrane,onionlike,rodlikemicellesPolymerself-assemblyPhasebehaviourofpolymers:LCST/UCSTbehaviourColloidosomesEncapsulationof“Material”bycolloidalshellsMicelles:Twoextremes,hairymicellesandcrewcutmicellesAssemblyintocolloidalstructures:polymersomesShell-crosslinkedpolymerassembliesToroidaltriblockcopolymerassembliesPeptide-amphiphilicnanofibersSupramolecularself-assemblyofmacroscopictubesProblems:1Pleaselistfourtypesofmorphologiesofdiblockcopolymersviaself-assemblyinbulk.2Pleaselistthreetypesofmorphologiesobservedinpolymeraggregates.Pleasedescribethemaindrivingforcesofself-assembly.Pleasedescribethedifferencesbetweenhairymicelleandcrewcutmicelle.Pleaselistfourindividualexamplesofhydrophobicandhydrophilicpolymersatambienttemperature.ChapterSix PolymerstructureandpropertiesHours：twoweeks，4hoursintotalContentsOverviewPolymersareorganic,chainmolecules.Theycanvaryfromafew,tohundredsofthousandsofatomsTherearethreeclassesofpolymersthatwewillconsiderinturn:Thermoplastic:flexiblelinearchainsThermosetting:rigid,3-DnetworksElastomeric:linear,cross-linkedRepresentingpolymerstructuresMolecularshapeMolecularstructureMolecularconfigurationsPolymercrystallinityThermoplasticpolymersgothroughaseriesofchangeswithchangesintemperature.(Similartoceramicglasses)Intheirsolidformtheycanbesemi-crystallineoramorphous(glassy).ThermoplasticsBondingalongthe“backbone”ofthechainiscovalent.Insimplethermoplasticpolymers,thechainsareboundtoeachotherbyweakerVanderWaal’sforcesandmechanicalentanglement.Therefore,thechainsarerelativelystrong,butitisrelativelyeasytoslideandrotatethechainsovereachother.AmorphousthermoplasticsGlassypolymers(T<Tg):Belowtheglasstransitiontemperature,amorphouspolymersarehardandbrittle.Rubberyorleatherypolymers(Tg<T<Tm):BetweenTgandTm,whenastressisapplied,thepolymerdeformselasticallyandplasticallyatthesametime.Whenthestressisremovedelasticdeformationisrecovered,butthepolymerispermanentlydeformedbecauseofthemovementofthechains.Liquidpolymers(T>Tm):Bondsbetweenchainsareveryweak,andchainsslidepasteachotherwithalmostnoforce.PolymercrystallinitySimilartometalsandceramics,polymerscanbemadetoexhibitsomelong-range(crystallize).Forpolymerstocrystallize,entirechainsmustbeordered.Crystallinethermoplastics:Linearpolymersnevercompletelycrystallize.However,polymerspartiallycrystallize.Neighboringchainsbecomealignedandfoldbackonthemselvestoformthinplates.Theseplatesareconnectedtoeachotherbyamorphouschainsandoftenformspherulites.Theabilityofapolymertocrystallizeisaffectedby:Complexityofthechain:Crystallizationiseasiestforsimplepolymers(e.g.polyethylene)andharderforcomplexpolymers(e.g.withlargesidegroups,branches)Coolingrate:SlowcoolingallowsmoretimeforthechainstoalignAnnealing:HeatingtojustbelowthemeltingtemperaturecanallowchainstoalignandformcrystalsDegreeofPolymerization:ItishardertocrystallizelongerchainsDeformation:SlowdeformationbetweenTgandTmcanstraightenthechainsallowingthemtogetclosertogether.DeformationofpolymersPolymerscanbe:Elastic–BrittleElastic–PlasticHighlyelasticDeformationofamorphouspolymersDeformationofthermoplasticpolymersismorecomplicatedthaninmetalsorceramics–Itdependsontheappliedstressandthestrainrate.Elasticdeformationistheresultofstretchingthecovalentbondsofthechainandtherotationofthecurvedchains.Onunloading,thestrainduetostretchingthechainsisrecoveredimmediately,andthestrainduetotherotationofthechainstakeslonger.Plasticdeformationinpolymersdoesnotoccurbythemotionofdislocations,anddeformationisaccomplishedbythemotionofpolymerchainsrelativetoeachother.Ifthepolymerisnotbrittle,afteryieldingthechainsbegintodisentangle,straightenandslidepasteachother.Neckingbeginsalmostimmediatelyafteryield,butthisisdifferentfromneckinginmetals.NeckinginAmorphousThermoplasticsDeformationofsemi-crystallinethermoplasticsElongationoccursfirstintheamorphousregionsbetweencrystallinelamellae.Crystallinelamellaebegintoaligninthedirectionoftheappliedstressandthenbreakintosmallersegments.Underanappliedstress,smallvoidscanopenupinbandsperpendiculartotheappliedload.Thisisknownascrazing.Inatransparentmaterial,thesevoidscanappearasanopaquebandthroughthematerial.Acrazeisnotacrackandcanstillsupportastress.Asthevoidselongate,theligamentsbetweenthemaresubjectedtohigherstressesandeventuallyfracturecausingthecrazetogrow.Eventually,thecrackgrowstoasizethatcausesrapidfracture.TimedependentdeformationDeformationisaccomplishedbythemotionofpolymerchainsrelativetoeachother.Slidingpolymerchainspasteachothertakessometime.Thisisviscoelasticbehavior.Athightemperaturesorlowstrainrates–MoreductilityAtlowtemperaturesorhighstrainrates–LessductilityCreepandstress-relaxationaretimedependentphenomena.Creep:changeinlengthatconstantloadStress-Relaxation:changeinloadatconstantextensionTemperaturedependenceofdeformationIncreasingtemperature:DecreasesYoung’sModulusDecreasestheYieldStrengthIncreasesductilityControllingthestrengthofthermoplasticsPlasticdeformationinthermoplasticsisduetotherotationandslidingofchainsovereachother.Toincreasethestrengthofathermoplastic,wehavetomakeitharderforthechainstomove.Thereareessentiallythreewaysthatwecancontrolthis:1.Alterthelengthofthechains;2.Changethestrengthofthebondswithinthechains;3.ChangethestrengthofthebondsbetweenthechainsFeaturesoftypicalpolymersElastomersThermoplasticelastomersThermosettingpolymersProblems:Atroomtemperature,whichtypesofpolymerswillactasglassypolymers,rubberyorleatherypolymers,andliquidpolymers?Pleasegivetwoindividualexamplesofthesepolymers.Pleaselistthreepolymerswhichcancrystallize.Pleasedescribethemainfactorstoaffectthecrystallizabilityofpolymers.Notions:glasstransitiontemperature,meltingtemperature,thermoplasticelastomer,thermoplasticpolymer,thermosettingpolymer.ChapterSeven PolymermodificationHours：twoweeks，4hoursinContentsPolymerizationtechniquesBulk:nosolventjustmonomer+catalystsSolutionpolymerization:insolventSuspension:micron-millimeterspheresEmulsion:ultrasmallspheresLesscommonpolymerizationtechniques:Solidstatepolymerization:Polymerizationofcrystallinemonomers,diacetylenecrystalsGasPhasepolymerization:lightolefin,parylenepolymerizationsPlasmapolymerization:PutanythinginaplasmaFeatureandweaknessofpolymersPlastics:fragile,unabletobearimpact,poorheat-resistantRubber:needtoimproveintensity,anti-freezingandoil-resistancePolymermodificationThepolymerperformancecouldbegreatlyenhanced,andnewfunctionscouldbebestowedmodification.Thepolymersarehenceofgreaterindustrialimportanceandcouldbeusedinvariousapplications.Therearevariouskindsofmethodsforpolymermodification.Generallyspeaking,itcanbeclassifiedintofivecategories:blendingmodification,fillingmodification,compositionmodification,chemicalmodificationandsurfacemodification.BlendingmodificationTheoriginalideaofblendedpolymersisthemixingoftwoormorekindsofpolymers,andmacroscopicallyhomogeneousmaterialsareconcoctedthereafter.Basi