高分子化學(xué)-Polymer-chemistry3自由基引論RADICAL-POLYMERIZATION課件

高分子化學(xué)

Polymerchemistry高分子化學(xué)

Polymerchemistry

RADICALPOLYMERIZATION自由基聚合

RADICALPOLYMERIZATION3.1MechanismofRadicalPolymerization3.2InitiatorsandInitiation3.3RateofRadicalPolymerization3.4MolecularWeightandChainTransferReaction3.5ThermodynamicsofPolymerization3.6MethodsofPolymerization3.1MechanismofRadicalPolyAnImportantOneofChainPolymerizationFamilyClassifiedbythenatureofreactivecenter:

radicalpolymerization

cationicpolymerization

anionicpolymerization

coordinatingionicpolymerizationandsoon.AnImportantOneofChainPolyChainpolymerizationconsistsofasequenceofthreesteps：

InitiationreactionPropagationreactionTerminationreactionChainpolymerizationconsists

PrimaryRadical引發(fā)劑

Initiator

Primary引發(fā)劑Initiator

MonomerRadicalPrimaryRadicalMonomerPrimary

MonomerRadical

ChainRadicalMonomerChainMacromoleculeMacromolecule高分子化學(xué)-Polymer-chemistry3自由基引論RADICAL-POLYMERIZATION課件TheRadicalPolymerizationisaveryImportantReactioninPolymerChemistryAleadingpositioninindustry:Productsofradicalpolymerizationcontributetomorethansixtypercentofthetotalproductionofpolymer,andeightypercentofthermoplasticresin.

TheRadicalPolymerizationisApracticallyperfecttheory:

Thegenerationandpropertyofradicalactivecenter;allelementaryreactionsandthereactionmechanism;thedynamicsofpolymerizationreaction;themolecularweightandthefactorsaffectingmolecularweight;Thermodynamictheory:AfullydevelopedtheoryThesehavebeenthetheoriesessentialtothestudyofionicandcoordinationpolymerization.Apracticallyperfecttheory:Table3.1ThepolymeroftheRadicalPolymerization

polyethylenePE

polystyrenePSpolyvinylchloride

PVCpolyvinylidenechloridePVDCTable3.1ThepolymerofthepolyvinylfluoridePVFpolytetrafluoroethylenePTFEpolychlorotrifluoroethylenePCTFE

polyacrylicacidPAA

polyacrylamidePAM

polymethylacrylatePMApolyvinylfluoridePVFpolymethylmethacrylatePMMApolyacrylonitrilePAN

polyvinylacetatePVAc

polybutadienePBpolyisoprenePIP

polychloroprenePCPpolymethylmethacrylate3.1

RadicalPolymerizationMechanism3.1.1Theactivityandthereactionofthefreeradical3.1.2Monomerstructureandtypesofpolymer-ization3.1.3Elementaryreactionsoftheradicalpolymer-ization3.1.4Characteristicsoftheradicalpolymerizationreaction3.1RadicalPolymerizationMe3.1.1

TheactivityandthereactionofthefreeradicalFreeradicalcanbeformedifthereareunpairedelectronorloneelectron.Theelectroniscalledmonoradicalifitistheonlyunpairedelectron.Ifthereareonlytwounpairedelectrons,theyarecalleddiradical.3.1.1TheactivityandthereaFreeRadicals

AtomicradicalsMolecularradicalsIonicradicals

ElectroneutralcompoundresidueFreeRadicalsAtomicradicalsGenerationofFreeRadicals

Thermaldecomposition

PhotochemicaldecompositionOxidation-ReductionreactionHighenergyparticleradiationGenerationofFreeRadicalsT（1）ActivityofTheFreeRadical

Theactivityofafreeradicalisdeterminedbyitsstructure.

Thestrongertheconjugativeeffectofafreeradical,themorestableitis.Polargrouplessenstheactivityofthefreeradical.Bulkygroup

lessenstheactivityofreaction,becauseitpreventsthenearingofthereagent.

（1）ActivityofTheFreeRadicTheOrderoftheRelativeActivity

ofRadicalsTheRadicalsinthelastlinearetheinertradicalsthathavenoabilityofinitiatingolefinicmonomers’polymerization

TheOrderoftheRelativeActi（2）ReactionsofRadicals

TheRadicaladditionreactionTheRadicalcouplingreactionTheRadicaldisproportionationreactionTheRadicaldissociationreactionTheRadicaltransferreaction（2）ReactionsofRadicalsTheR

①RadicalAdditionReaction

．．．

①RadicalAdditionReaction

．②RadicalCouplingReaction②RadicalCouplingReaction③RadicalDisproportionationReaction③RadicalDisproportionationR

④RadicalDissociationReaction

④RadicalDissociationReacti

⑤RadicalTransferReaction

⑤RadicalTransferReaction

Mostofthemonoolefin,conjugateddiolefin,alkyne,

andcarbonylcompounds,andsomeoftheheterocycliccompoundscanbepolymerizedfromthethermodynamicviewpoint.

3.1.2

MonomerStructureand

PolymerizationTypesMostofthemonoolefin,conjHowever,

theselectivityofthevariousmonomerstodifferentpolymerizationmechanismsvariesgreatly.However,theselectivityofExamples

Vinylchlorideonlycanundergoradicalpoly-merization.Isobutyleneonlycanundergocationicpolymer-ization.Methylmethacrylatecanundergoradicalaswellasanionicpolymerization.Styrenecanundergoradical,anionic,cationic,andcoordinationpolymerization.ExamplesVinylchlorideonlyWhatmakesthedifferencesismainlydecidedbythestructureofthesubstitu-entonthecarbon-carbondoublebond,andisalsodecidedbytheelectroniceffectandthestericeffectofthesubstituent.Ethylene,themostsimplealkene,withasymmetricstructure,canundergoradicalpolymerizationunderhighpressure,

andcoordinationpolymerizationbyparticularinitiatorsystems.WhatmakesthedifferencesisMonosubsititutedAlkeneDoubleBondMonomersCH2＝CH－X,theelectroniceffectofthesubstituentsXinvolvestheinductiveorresonanceeffect.Theeffectofsubstituentmanifestsitselfbyitsalterationofelectron-clouddensityonthedoublebondandithastheabilitytoaffectthestabilityoftheactivecenter.MonosubsititutedAlkeneDoublWhetheranalkenepolymerizesbyradical,anionic,orcationicinitiatorsdependsontheinductiveandresonancecharacteristicsofthesubstituentspresent.WhetheranalkenepolymerizesToCH2＝CH－X,whenXiselectron-pushingsubstituentItincreasestheelectron-clouddensity,facilitatingitsbondingtoacationicspecies.

Further,thesesubstituentsstabilizethecationicpropagatingspeciesbyresonance,anddecreasetheactivationenergyofthereaction.Thus,electron-pushingsubstituentsfacilitatethemonomerstocationicpolymerization.ToCH2＝CH－X,whenXiselectrElectron-pushing

substituentssuchasalkyl,alkoxy,phenyl,andalkenylTheeffectofalkylgroupsinfacilitatingcationicpolymerizationisweak,

Anditisonlythe1,1-disubstitutedalkeneswhichundergocationicpolymerization.

CH3

CH2=CCH2=CHCH3ORElectron-pushingsubstituents

ToCH2＝CH－X,whenXis

electron-

withdrawingsubstituent

Itlowerstheelectron-density,andstabilizesthepropagatinganionicspeciesbyresonance.And,thus,itfacilitiesanionicpolymerizationofthemonomers.

ToCH2＝CH－X,whenXis

eleElectron-withdrawingsubstituents:cyanoandcarbonyl(aldehyde,ketone,acid,orester)Radicalpolymerizationissomewhatsimilartoanionicpolymerization.Electron-withdrawingsubstituentsfacilitatetheattackofananionicspeciesbydecreasingtheelectron-densityonthedoublebond.Theystabilizethepropagatingofanionicspeciesbyresonance,whichweakenstheactivationenergyofthereaction.Electron-withdrawingsubstituStrongelectron-withdrawingsubstituents

facilitatethemonomerstoanionicpolymeri-

zationwithweakeronesincliningtoradical

polymerizationMonomerswithsubstituentsbetweenthetwocanundergoeitheranionicorradicalpolymerization.Halogensubstituents,althoughelectron-withdrawinginductively,canresonancestabilizetheanionicpropagatingspecies,however,bothoftheeffectsareweak.Strongelectron-withdrawingConjugated

AlkeneStyrene,butadiene,isoprene,andotherconjugatedalkene,becauseofitsstrongdelocalizationoftheπ-bond,areeasytobeinducedandpolarized,thus,canundergoallofthefourmodespolymerizationmentionedabove.CH2=CH-CH=CH2CH2=C-CH=CH2CH3CH2=CHConjugatedAlkeneStyrene,butStericEffect

oftheSubstituentStericEffect-----thevolume,amount,andlocationofthesubstituent.

Inkinetics-----Itproducesanoticeableeffectonthecapabilityofpolymerization.However,itusuallydoesn’tcontaintheselectivitytodifferentactivecenters.StericeffectsofmonosubstituentsarenotobviousStericEffectoftheSubstitue1,1－disubstitutedalkenemonomersStericeffectsusuallybeingignored,

theactivityandselectivityofthemonomersareonlythoughttobedecidedbytheelectron-effectofbothsubstituents.However,whenbothofthesubstituentsarephenylgroups,becauseofitslargebulk,monomerscanonlyformdipolymer.

RCH2=CR’1,1－disubstitutedalkenemonom1，2－disubstitutedmonomersOwingtostrongstericeffect,thiskindofmonomersareusuallyhardtopolymerize.

Forexample,maleicanhydrideishardtohomopolymerize,butcancopolymerizewithstyreneorvinylacetate.

CH=CHRR’1，2－disubstitutedmonomersOwinTriortetrasubstitutedethyleneTheyususllycannotpolymerize.But,thereareanexceptionwhenthesubstituentisfluorin.Owingtothesmallradiusofthefluorin,allofthem,

frommonototetrasubstitutedfluoroethylene,

canpolymerizewell.Triortetrasubstitutedethyle3.1.3

ElementaryReactionsofRadicalPolymerizationRadicalpolymerizationischainpolymerizationComposedbyatlestthreeelementaryreactionsChaininitiationChainpropagationChainterminationPerhapsaccompaniedbychaintransferreactionandsoon3.1.3ElementaryReactionsof

PrimaryRadical

MonomerRadical（1）ChainInitiationReaction

heatabsorptionheatliberation

Initiator

MonomerPrimaryMonomer（1）ChainInit

PrimaryRadicalThedecompositionofinitiatorsisaheatabsorp-tion

reaction.Witharelativelyhighactivationemergy,about100～170KJ/molPrimaryRadicalPrimaryThedecompositionofDecompositionrateconstantisusually

10－4～10－6/s

Thereactionrateisrelativelyslow.Initiatordecompositionreaction-----controlstheoverallrateofthechaininitiation.Decompositionrateco

MonomerRadical

MonomerTheprimaryradicalsaddtomonomerstoproducemonomerradicals.Theprocessofopeningaπ-bond,andproducingaσ-bondisaexothermalreaction.MonomerRadicalMonomerMonomerTheprimaryraWithalowactivationenergy,about20～34kJ/mol

Andagreatreactionrateconstant.Thisisaveryfastreaction.

Withalowactivationenergy,(2)ChainPropagationReaction

(2)ChainPropagationReactionHead-to-TailstructureHead-to-HeadstructureTail-to-TailstructureHead-to-TailstructureHead-to-（3）ChainTerminationReactionRadicalExhaustionCouplingTerminationDisproportionationTermination（3）ChainTerminationReactionR

Monoradicaltermination------

ExhaustsoneradicalinitiatorBiradicaltermination------couplingtermination;disproportionationterminationMonoradicaltermination------Biradicaltermination------

couplingtermination;

disproportionationterminationCouplingTermination----Thedegreeofpolymerizationisthesumofthemonomericunitsofthetworadicalchains.

Thetwoendsofthemoleculearetheresiduesoftheinitiators.Biradicaltermination------

Terminationofdisproportionation----TheDegreeofPolymerizationisthenumberofthemonomericunitsoftheradicalchain.Eachmoleculecontainsainitiatorresiduesend.However,theterminatedchemicalstructuresofthetwomoleculesaredifferent,onesaturated,andtheotherunsaturated.TerminationofdisproportionatThemodesofterminationreactionsaredeterminedbythemonomerstructureandthepolymerizationtemperature.

ThemodesofterminationreacThemodesoftermination------

monomerstructure

polymerization

temperatureWithbulksubstituents-----thepossibilityofdisproportionationterminationincreases.Atlowpolymerizationtemperature----tendingtocouplingtermination.Themodesoftermination------Therelativescaleofcouplingtodisproportionationterminationis：TherelativescaleofcouplingTable3-3ModesofsomeMonomerRadicalTerminationPolymerizationcouplingDisproportionationMonomerstemperaterminationterminationStyrene0～60℃100％0％

P-chlorostyrene

60、801000P-anisole

styrene

608119805347Methylmethacrylate04060253268601585

Acrylonitrile40，60928

Vinylacetate90～100Table3-3ModesofsomeMonomTable3-4ComparisonbetweenChainPropagationandChainTerminationReactionPropagationrateconstant[L/(mol·s)]Monomerconcentration[M]:10~10-1[mol/L]Propagationrate[M][M·],10-4～106[mol/(L·s)]Rateconstantoftermination

[L/(mol·s)]Radicalconcentration[M·]:10-7～10－10[mol/L]Terminationrate[M·]2,10-8～10－10[mol/(L·s)]Table3-4Comparisonbetween（4）ChainTransferReaction

TomonomerTosolvent(ortochaintransferagent）ToinitiatorTopolymer

（4）ChainTransferReactionTo

[1]

tomonomer[2]

Tosolvent(ortochaintransferagent）[1]

tomonomer[2]Tosolven[3]

toinitiator[4]

tomolecule[3]

toinitiator[4]

tomoCharacteristicsofRadicalPolymerizationFrommicroscopicview,radicalreactionconsistsoffourelementaryreactions--initiation,propagation,termination,andtransfer.Therateofinitiationisthelowestone,whichcontrolstheoverallrateofpolymerization.Inconclusion,thecharacteristicsofradicalpolymerizationareslowinitiation,fastpropagation,fasttermination,andeasytransfer.CharacteristicsofRadicalPolThedegreeofpolymerizationincreasesonlyinthepropagationprocess.Inthesystemthereareonlymonomersandpolymers,nointermediatecompounds.ThedegreeofpolymerizationiProlongingthereactiontimeismainlytoincreasetheconversionrate,withlittleeffectsonthemolecular-weight.However,geleffectwillincreasethemolecular-weight.Asmallamount（0.01%～0.1%）ofinhibitorsisenoughtoterminatetheradicalpolymerization.ProlongingthereactiontimeRadicalPolymerizationCondensationPolymerizationElementaryreactions’rateconstantsandactivationenergyaredifferentElementaryreactions’rateconstantsandactivationenergyarealmostsamelyDegreeofpolymerizationdoesnotchangewithpolymerizationtime

Molecularweightincreasesgraduallyandafairlylongtimeisneeded.Thepolymermolecularwei-ghtiscomparativelysmallNointermediateproductswhosedegreeofpolymeri-zationareincreasingPolymerizationprocessinvolvesallmonomersTable3-5ComparisonoftheCharacteristicsofRadicalandCondensation

PolymerizationRadicalPolymerizationCondensaRadicalPolymerizationCondensationPolymerizationNoremarkablechangeofmolecularweightwithprolongedreactiontimeandhigherconver-sion.

Molecularweightofproductincreaseswithpolymerizationtimebutconversionincreaseslittle

exothermicreactionShouldbeheatedtohightemparetureAccompaniedwithrobabilitiesofbranch-ingandevencrosslinkingNobranchingRadicalPolymerizationCondensa3.2InitiatorandInitiation3.2.1TypesofInitiators3.2.2KineticsofInitiatorDecomposition(1)InitiatorDecompositionRate(2)InitiatorEfficiency(3)ChoiceofInitiator3.2.3OtherInitiation(1)Thermal-initiatedpolymerization(2)Lightinitiatedpolymerization(3)Highenergyradiationinitiatedpolymerization3.2InitiatorandInitiation3.3.2

InitiatorandInitiationInitiationisaprocesswhichconvertsolefinicmonomerstoradicals.Primaryradicalscanbeproducedthroughlight,heat,orhighenergyradiationdirectlyactingonmonomers.But,whatusedmoreoftenisinitiator.Initiatorshaveweakbonds,Thermaldecompositioncanproducetwoprimaryradicals.3.2InitiatorandInitiationIn3.2.1TypesofInitiatorsAzoinitiatorOrganicperoxideinitiatorInorganicperoxideinitiatorRedoxinitiationsystem

3.2.1TypesofInitiatorsAzoi（1）AzoInitiator

azobisisobutyronitrile（AIBN）

azo-bis-iso-heptonitrile（1）AzoInitiatorazobisisobut（2）OrganicPeroxideInitiatordibenzoylperoxidedialkylperoxide

（2）OrganicPeroxideInitiator（3）InorganicPeroxideInitiatorpersulphate（3）InorganicPeroxideInitiato（4）Redoxinitiationsystemcomponents：inorganicandorganicproperties：oleiferous

solubilityandaqueoussolubility（4）RedoxinitiationsystemcompforinstanceThermaldecompositionactivationenergyFrom200downgradeto40KJ/mol

From125downgradeto50KJ/molFrom140downgradeto50KJ/molIntheredoxsystemofaqueoussolubility,inorganicreducersareusuallyused,andasmallamountof

organicreducers,suchasalcohol,amine,andsoon,areusedtoo.

forinstanceThermaldecompositSystemsofOleiferous

SolubilityareOftenUsedInitiatorstertiaryamine，naphthenate，mercaptan，metalloorganiccompoundSystemsofOleiferousSolubiliExamplebenzoylperoxideandN，N－dimethylanilineinitiatingsystemExamplebenzoylperoxideandN，

SomemetalloorganiccompoundsTaketrialkylboranelforexample,itcanreactwiththeoxygenintheair,andformaredoxinitiationsystem,whichcaninitiateolefinicmonomerspolymerizationatalowtemperature.Somemetalloorganiccompound3.2.2

DecompositionKineticsofInitiatorIneachelementaryreactionofradicalpolymerizationInitiationrateisthelowestone.Haveastrongeffectonbothoverallpolymerizationrateandmolecularweight.ChaininitiationrateControlledbytheinitiatordecompositionrate.Bystudyingtheinitiatordecompositionrate,wecanfindthequantitativerelationshipbetweentheradicalgenerationrateandtheinitiatorconcentration,temperature,andtime.

3.2.2DecompositionKineticso（1）ThermalDecompositionRateofInitiatorInitiatorthermaldecompositionisafirstorderreaction.initiatorPrimaryradicalDecompositionrateofinitiatormol/(L·s)

Rateconstantfordecompositions-1

integratedAtagiventemperature，throughtheplotofln([I]

/[I]0)totimet

Rateexpression（1）ThermalDecompositionRate（1）ThermalDecompositionRateofInitiatortheplotofln([I]

/[I]0)totItsslope=-kd

ln([I]

/[I]0)t/min0.0-0.4-0.80.080160240320=[(-0.4)-(-0.8)]/(160-320)60=-4.2x10-5(s-1)（1）ThermalDecompositionRateThehalflifeofthefirstorderreaction-t1/2

Tothefirstorderreaction,weusuallytakethehalflifetocharacterizethereactionrate.Halflifeisthetimeneededfortheinitiatortodecomposetohalfitsoriginalconcentration.

ThehalflifeofthefirstordeArrheniusformulation

ThedependenceoftherateconstantforinitiatordecompositionontemperatureisinconformitytoArrheniusformulation.Theplotoflnkdto1/Tshouldbeastraightline.Frequency

factor-Adcanbeworkedoutfromtheintercepting.

Thedecompositionfreeenergy-Ed

canbeworkedoutfromtheslope.ArrheniusformulationThedepeTable3-6KineticParameterof

SomeTypicalInitiators

InitiatorssolventT/oCkd/S-1t1/2/hEd/kj/molAIBN502.64*10-673128.460.51.16*10-516.669.53.78*10-55.1BPObenzene602.0*10-696124.3802.5*10-57.7cuminehydroperoxide

toluene1259*10-621.41393*10-56.4potassiumPersulphate0.1mol/603.16*10-661140.2L.KOH702.33*10-58.3Table3-6KineticParametero（2）EfficiencyofInitiationOnlyapartofprimaryradicalsareeffectiveininitiatingmonomerspolymerizing.Someinitiatorsareexhausted,becauseofthesidereactionsaccompanyingwiththe

induceddecomposition,and/orthecageeffect.

Theefficiencyofinitiationisdefinedastheratioofinitiatorswhichareusedtoinitiatepolymerizationtoinitiatorsthatdecomposeinthewholeprocessofpolymerization,andisdenotedasf.

（2）EfficiencyofInitiationOnl①I(mǎi)nducedDecompositionofInitiatorsThechaintransferreactionfromfreeradicalstoinitiatormolecules.Thetotalnumberoffreeradicalsarenotincreased,however,oneinitiatorisexhausted,whichlowerstheefficiencyofinitiation.①I(mǎi)nducedDecompositionofInFactorsImpactontheEfficiencyofInitiationTheefficiencyofinitiationdependsontheinitiatortype.TheinduceddecompositionofAIBNisverylittle.Hydroperoxideeasilyundergoesinduceddecomposition,whichmakestheefficiencyofinitiationlowerthan0.5.FactorsImpactontheEfficienThetypeofmonomersalsoaffectstheefficiencyofinitiation.Monomerswithhighactivity,suchasstyrene,andacrylonitrile,canreactwiththefreeradicalsrapidly,andreducetheinduceddecomposition.Incontrast,theabilityofcapturingfreeradicalsisrelativelypoorforvinylacetatetypemonomers,sothevalueoffisfairlylow.ThetypeofmonomersalsoaffeDecompositionRateofInitiatorsInduceddecompositionusuallyincreasesRd,anddecreasest1/2.Whenaccompaniedbyinduceddecomposition,thedecompositionrateofinitiatorscanbeexpressedbyNormalfirstorderdecompositionrateInduceddecompositionrateBetween1and2

DecompositionRateofInitiato②CageEffectTheinitiatorconcentrationisverylowinpolymerizationsystem,sotheprimary

radicalsarebesiegedbythecageofsolventmolecules.

Inordernottoreactwitheachother,primaryradicalsmustgetoutofthecage.Thelifeexpectancyoffreeradicalsinthecageisabout

10－11～10－9S②CageEffectTheinitiatorconForexampleSidereactionsofcageeffectofAIBNForexampleSidereactionsofc

SidereactionsofcageeffectofBPOSidereactionsofcageeffect

Table3-7EfficiencyofInitiationofAIBNTheefficiencyofinitiationdependsontheinitiators,monomers,solvent,systemviscosity,andotherfactors.ThevalueoffofAIBNtodifferentmonomersMonomersf,%Monomersf,%AN～100VC70～77Styrene～80MMA52VAC68～82Table3-7EfficiencyofIniti③TheChooseofInitiatorsFirstly,accordingtothepolymerizationmethods,Initiatorswitholeiferous

solubilityareOKforbulk,solution,andsuspensionpolymerization.InitiatorswithaqueoussolubilityareOKforemulsionpolymerization.Secondly,accordingtothehalflife,

Thechoseninitiatorshouldhaveahalflifecomparativetoorofthesameorderwiththetimeofpolymerization③TheChooseofInitiatorsFirsThirdly,thedosageofinitiatorshouldbereasonable,Theinitiatorconcentration[I]affectsnotonlytherateofpolymerization,butalsothemolecularweightoftheproducts,further,ithasaoppositeeffect（aftermentioned）Theproperinitiatorconcentrationdependsonanamountofexperiments.Thirdly,thedosageofinitiatInaddition,suchasprice,source,toxicity,stability,theeffectonthecolorshadeofpolymers,andsoon,shouldalsobecountedintoconsideration.Inaddition,suchasprice,so3.2.3

Other

InitiatingAbilityThermal-initiatedpolymerizationMonomerscanpolymerizeunderthefunctionofheat,withoutinitiator,whichiscalledthermal-initiatedpolymerization,orforshort,thermalpolymerization.Photo-initiatedpolymerizationUnderlightirradiation,manyolefinicmonomerscanproducefreeradicals,whichcaninitiatepolymerization.Wecallthislightinitiatedpolymerization.Highenergyradiationinitiatedpolymerization3.2.3OtherInitiatingAbility(1)

Thermal-InitiatedPolymerizationStyreneisusedmosttostudythemechanismofthermalpolymerizationTherateofinitiationis

(1)Thermal-InitiatedPolymeriStyreneThermalPolymerizationIftheconversionofstyrenethermalpolymerizationreaches50percent400daysareneededat29℃.235minutesareneededat127℃.Only16minutesareneededat167℃.StyreneThermalPolymerization(2)Photo-InitiatedPolymerizationLightquantumenergy

Planckconstant

ThespeedoflightThefrequencyoflight

ThewavelengthoflightPhoto-initiatedpolymerizationcanbedivideintodirectlightinitiatedpolymerizationandphotosensitivepolymerization.(2)Photo-InitiatedPolyme①DirectLightInitiatedPolymerization

LightquantumMonomermoleculeExcitedst