ChapterIonicChainPAGE1CationicAnioic YCationicAnioic Y YY:anelectron-releasingalkoxy(OR)Y:anelectron-withdrawingnitrile(CN)carboxylC6-1aHsp2

C

STABILIZATIONOFSUBSTITUENTSRCTheionicpolymerizationhasaverystrictrequirementsforstabilizationofR++4FIG1.Resonanceandstabilityofionicpropagating5烯烴中唯一能子聚合的6丙烯 甲基丙烯酰 苯乙 322327661b大多數離子聚合包括兩種類型的增長種：離子對和自由離子它們共存于平衡中。緊密離子對(2)和溶劑分子對(3)的比例依溶劑性質對離子聚合的影響極其顯著，因為不同類型的增長種具不同于自由基聚合，在離子聚合中不會發生增長鏈之間的雙分子8c的活性種（離子）極性溶劑（水、醇）：破壞離子酮：與劑形成穩定的絡合低極性或中等極性溶劑：CH3(CH2)3CH3,CCl4,CH3Cl,ClCH2CH2Cl,PhNO2,etc.大多數子聚合反應的劑為非均相無機物，對雜聚合機理聚合機理3 3 LewisMetalhalides:AlCl3,BF3,SnCl4,SbCl5,ZnCl2,TiCl4,PCl5Organometalliccompounds:RAlCl2,R2AlCl,

酸是最重要的用于子聚合的劑。其中，AlCl3已在工業上廣Oxyhalides:POCl3,

泛應用 子聚Lewisacid+proton/carbocationTheinitiationAdvantage:Theanion(IZ)-isfarlessnucleophilicthanA-.Thisprolongsthelifeofthepropagatingcarbocationandallowspropagationtoproceedtohighermolecularweight. Activity:Deenin ontheinititr cinititr,slvent monomer.ThevalueofK(inEq.6-1a)andthevalueofki(inEq.6-1b)generallyincreasewithincreasingacidityoftheacid,alsoproportionaltotheacidityof通常，一級和二級鹵代烴不能用作子聚合的有效劑。通常，一級和二級鹵代烴不能用作子聚合的有效劑。StabilityofC+:1<2<33C2NN- CcycloheptatrienylC7H7 SnCl4:0.08SnCl4:0.126

SnCl+H (H3O) SnCl4+ SnCl4

(V

0

theinitiator-coinitator[H2O](104), FIG.2EffectofwaterconcentrationontheSnCl4initiated

becausethebasicityoftheC=Cdoublebondisfarlessthanthatofstyrenein

at Iodineisuniqueamongthehalogensinthatitinitiatespolymerizationofthemorereactivemonomers(styrene,vinylether,N-

+CH=CH ICH-CHI HI+ H+I3(theinitiating vinylcarbazole, evenintheabsenceofa Photoinitiator 2aryldiazoniumArN+Z- triarylsulfoniumAr3S+Z-2 Z-=BF-,SbF-,PF- Theinitiatorionpairproceedstopropagatebysuccessiveadditionsofmonomermolecules,ceedingbyrearrangementareCH2=CH-proceedingbyrearrangementareCH2=CH-3-methyl-1-CH2-Temp./--therearangedunit

thefirstformed theFerrarisetal.:Highresolution1Hand13CHH2CH-2H:H:3222 CsCHHC3CH3 CH Theextentofrearrangementduringcationicpropagationwilldependontherelativestabilitiesofthepropagatingandrearrangedcarbocationsandtherelativeratesofpropagationand向單體的鏈轉移常數：向單體的鏈轉移常數：Mp. M,MWChainTransferandChainTransfertoMonomerModeH[CH2C(CH3)2]n + H[CH2C(CH3)2]n+H H[CH2C(CH3)2]n+H[CH2C(CH3)2]nModeH[CH2C(CH3)2]nCH2CH(CH3)2+CH2=C(CH3)-+M (6-SpontaneousTerminationHH[CH2C(CH3)2]nH[CH2C(CH3)2]nCH2C(CH3)=CH2+BF3+自發終止：增長離子對發生重排導致鏈終止，形成帶不飽和端基 自發終止亦稱向反離子轉移，在動力學上不同于向單體轉移；前ExampleH(CHExampleH(CH2CH)nCH2CHH(CH2CH)n ExampleH[CH2C(CH3)2]nH[CH2C(CH3)2]nCH2C(CH3)2(OH)+H[CH2C(CH3)2]nH[CH2C(CH3)2]nCH2C(CH3)2Cl+Terminationbycombinationdiffersfromtheothermodesofconcentratio of initiato-coinitiato complexdecreasChainTransferto CH2-CH-CH2-

+Haterminalindanyl molecularhydridetransfertopolymerprobablyfortheshort-chainbranchingfoundinthe olmerizationoffortheshort-chainbranchingfoundinthe olmerizationof-alkenessuchaspropylene.R+RHaRC-H+R3oOtherTransferandTermination鏈轉移劑（chain-transferagents：溶劑、雜質或有意添加到反應體系Althoughachain-transferagentdecreasesthedegreeofpolymerizationinproportiontoitsconcentration,itisnotexpectedtoaffectthepolymerizationratesincetheinitiator-coinitiatorcomplexshouldberegeneratedontransfer.聚合度下降，聚合速率未必下降。Often,water,alcohol,ammonia,andaminesusedinexcess6-2b. Kinetic假設聚合機理由式Eq.6-1a、6-1b，Eq.6-2和6-5組成，即終止方式為穩態假定：采用類似于自由基聚合動力學推導的穩態條件（Ri 除了“增長中心與反離子結合”外，當鏈終止反應還同時包括“向單體鏈轉移”(Eq.6-3)、“自發終止”(Eq.6-4)和“向鏈轉移劑(S)少而不致于使劑失活）。但是，這些鏈終止使聚合度下降。 =RXnRt

+

+

+

(6-

Rts=kts[YM+(IZ) (6-Rtr,M=ktr,M[YM+(IZ)][M](6-Rtr,S=ktr,S[YM+(IZ) (6-

CS Rp= - Rt=kt[YM+(IZ)- (6-

Xn

kt+

+

[M]+

+CM+

(6- (6- RRpkt+ 如果在過程中，劑-共劑絡合物的形成反應(Eq.6-1a)是決速步驟，則速率不依賴于單體濃度：Eq.6-17。速率表.

p[M]Ri= (6- Kinetic子連鎖聚合反應各種速率常數(kikpktktsktr)的測定并非TABLE1.Kineticparametersinstyrenepolymerization 0.270.40

2 3.81037.1 2

1023Liters/mol- 4.2107

K 1.2106Liters/mol- 1.2105Liters/mol-

170280

Kp:Ion-pairpropagationrate <

14103Liters/mol-NOTE:Generally,nomorethantheoneorderofmagnitudedifferencebetweenkp+andkp.TABLE2.PropagationRate015 Ph3C+SbCl CH PropylvinyletherPh3C+SbClCHCl Whycationicpolymerizationaregenerallyfaster Cationicvsradicalkp(cationic)/kp(radical),kt(catioic)<<Rpcationickp/kt,Rpradicalkp/kt1/2radical,theformerratioislargerthanthelatterbyupto4ordersofmagnitudedependingonthe

10-5mol/L,[P](radical)10-7~10-9TABLE3.Monomerchain-transferconstants Isobutylenein一般說來，具有較大kp的單體，CM較小。CM101~102，比自由單體聚合活性次序:乙烯基醚>異丁烯>苯乙烯>異戊 TABLE4.Chain-transferconstantsforsome(CS)instyreneInitiatoror CS102 0含有易解離的負電荷碎片（如甲醇中的CH3O）隨劑、共劑或溶劑種類的改變，同一鏈轉移劑的鏈轉移c.影響子聚合的因溶劑效應SolventEffects 溶劑極性影響自由離子和離子對TABLE5.Effectofsolventonolmerizationofp-methoxstrene I2atCH2Cl2/CCl4CH2Cl2/CCl4kpapp

溶劑能改變不同增長物種的增長速率常數，從而影響聚合速率和聚Thekpappincreasesbymorethan2ordersofmagnitudeingoingCCl4(=2.24)toCH2Cl2(=9.08).Specificsolvationandpolarizationeffectsmaybeimportantinaparticularsystem. 反離子效應CounterionTABLE6. olkpapp,Liters/mole-

及-鍵到-鍵不論方式，，ER–20~40NOTE:負的ER并非意味著達到過渡態只需負的活化能。任何基元反應的活化能都為正值。R值為負只表明t大于(i+p).Temp.tRp聚合度綜合活化能：Exn–12.5~–29聚合度綜合活化能總是負值，因為不論鏈終止方式如何，Et或通常大于Ep。提高溫度更有利于加快終止或鏈轉移速率，因此， nFig.3TemperaturedependenceofXnforthealuminumchloride(AlCl3)polymerizationof

顯改變，對應于Exn=–23.4–3.1kJ/mole。表明隨溫度變化，鏈終止方式由向單體鏈轉移（低于–100℃）100℃）。這種Exn轉變也可（至少部份）歸因于溫度對不同類型增長物種相對比例的影響 Commercialapplicationsofcationicpolymerization 聚異丁烯Pl l Acopolymercontaining~80%isobutyleneand20%otherbutenes(mainly1-butene)Mn<sealants,lubricants, additivesformotoroils,etc.LowMWMv5~10104:sealant,HighMWMv>105:uncured(uncrosslinked)rubberproducts,impactmodifiers Chewing Butl BR SportingAcopolymerofisobutylenewithsmallamountsofisopreneproducedbyAlCl3initiatedpolymerization.

forthebladdersinbasketballs,footballs,soccerballsandotherinflatableballstoprovideatough,airtightinnerRoofGasmasks&chemicalagentprotection在陰離子聚合中，增長物種是離子對（anionicionpair）和自由陰離子（ions），兩者的相對濃度如同子聚合一樣依賴于反與子聚合不同，在陰離子聚合中離子對和自由陰離子的活性盡管陰離子聚合通常在低溫下快速進行，但很少像 子聚合那樣對溫度敏感；絕大多數陰離子聚合反應具有正的活化能（ER），可在常溫或略高于常溫下進行。溶劑：脂肪族和芳香族烴、醚。鹵代溶劑、極性溶劑（酯和酮）劑Nucleophilic劑Nucleophilic親核試劑（B:orB:）：NaNH2、LiN(C2H5)2（Alkoxide）、氫氧化物、化物（Cyanides）、膦、胺、n-C4H9Li,、PhMgBr等。compoundsareprobablythemostusefuloftheseinitiatorsduetotheirgoodsolubilityin電子轉移ElectronTransferOverberger

Li/NH3

+

LiNH2/NH3 asolvated 電子轉移也可發生在非均相聚合中，過程包括堿金屬在單體乙SrR2,Na,RNaLi,RLi

t-

strongweakbases

2CH(CH3)CN

Theinitiatorrequiredtopolymerizeamonomerdependsonthe PolymerizationWithout 整聚合過程中，增長中心（碳負離子）有的色保不變，即使單體轉化率達到100％其顏色也不 或改變達到100 TransferAgents(H2O,O2,CO2,ROH,etc.) Spontaneous

聚苯乙烯陰離子在活性陰離子體系中最為穩定，在CH2CH-CH2-C:-CH2CH-CH2-C:-Na+HCH2-C:- CH2CH- CH2-CH2Ph CH2C-

烴類溶劑中可存活數周。 1,3-diphenylally括對-H的奪取和/或對CO括對-H的奪取和/或對CO鍵的進TerminatingTerminatingReactionsofPolar CH2=C-C-OCH3+R-Li+ CH2=C-C-R+CH3O-

Acopolymer

alkylketone

MMAandtheRpslow

O

COOCH3+ i. ii.OH H2

CH2=CH-C-methylvinyl

H32CH32CH 2CO2O

Similarly,acrylonitrilepolymerizationiscomplicatedbyadditionnitrilegroup.6-3cKineticsofLiving pp-I[M-]isthetotalconcentrationofalltypesoflivinganioniccenters ionsandion快 0pt討論Eq.6-17適用于速率比增長速率快的情形。這個條件在極性溶改進的膨脹計測定技術：將毛細管內的反應物流入含有終止劑的溶劑中來終止聚合反應，通過定量分析被淬滅的反應混合物（聚合物或未反應單體）來獲得轉化率、Rp和kpapp.Themajordifferenceintheratesofanionicandradicalpolymerizationsresidesinthelackofterminationinanionicpolymerizationandthelargedifferenceintheconcentrationsofthepropagatingspecies.DegreeDegreeof于為消耗的單體濃度與活性端假定通常的情形：所有的引發劑I全部轉變為增長活性對于快速、高效混合的活性陰離子聚合體系（不存在降解、終止和EffectsofReactionTABLE7.Effectofsolventonanionicpolymerizationofconstant()253**Sodiumnaphthalene(310-3mole/L),表觀速率常數kpapp隨反應介質溶劑化能力的提高，其主要原因是自由PC++M ion

PM

[P]K [P Forthecase [P-]= +C++ +

[P-]=(K[P- Rp=kp[P][M]+kp[P

R=-d[M]/dt=

[M-

K(~10-

(6-

[P-C+]=[M-kp[P]+kp[Pkpapp

[P-]=(K[M- [M

[P-C+]=[M-]-(K[M-])1/2(6- (kp-kp)kp=kp[M-

CZ來提供，如：加入NaBPh4可提供過量的Na+）。[P]=因為外加鹽容易解離，而離子對解離傾向很小，則反離子濃度非常接近外加鹽的濃度[CZ]:[C+]則：自由陰離子的濃度:[P離子對的濃度:[PC+[MppKp600400 kp200 measurements:K,[P-]and[P-0 10 20 30 40 [M-]-1

60 70Fig.4Polymerizationofstyrenebysodiumnaphthalenein3-methyltetrahydrofuranat20C.200kp1000 10-5/ ofstyrenebysodiumin3-methyltetrahydrofuranat20Cinthepresenceof inAnionicPolTable8.EffectofCounteriononAnionicPolymerizationofPolymerizationPolymerizationinforKKkp>>kp自由離子的反應活性比離子對大102~103。K值變化趨勢與反離子的溶劑化程度一致。K值變化會顯著影響高活性自由LiCs，這是因為溶劑分子對所占分數隨反離子溶劑化程度對于二氧六環體系，得不到Kkp數據。(kp±)Dioxane<(kp±)THF，且變化趨勢與THF體系相反。在二氧六環中，較活潑的溶劑分子對所占分數較小；高活性的離子對是那些與反離子弱鍵合的離子對 溫度的影響.溶劑分子對和緊密離子對的反應活 ER=37.6kJ/molindioxane;4.2kJ/molin溫度對增長反應速率的影響比較復雜Temp., ,kpKP子對與自由Table9.ProaationofsodiuminTHFat20Col子對與自由Table9.ProaationofsodiuminTHFat20Colstr這表明溶劑分1.31.3 24liters/mole-5.5 ..1,溶劑分子對的活性不易受反離子的影響。SeekpinTHF(Tab.8)..AssociationPhenomenainAcomplicationforpolymerizationinitiatedbyRLiinnonpolarsolventsisassociation(aggregation)ofthevariousorganolithiumspeciespresentinthereactionsystem.Thefractionalkineticordersonlymonomericinitiatorandpropagatingionpairsarereactive.PolymerizationinaliphatichydrocarbonsisconsiderablythaninaromaticTheassociationphenomenaoccurringwithalkyllithiuminitiatorsinnonpolarsolventsresultsinverylowpolymerization18-crown- Block6-4aSequentialMonomerSequentialadditionofmonomerstoalivinganionicpolymerizationsystemisatpresentthemostusefulmethodofsynthesizingwell-definedblockcopolymers.Thepropersequencingofadditionsofdifferentmonomers.Forexample:(St-b-MMA)copolymer. PS的堿性比PMMA強DifunctionalinitiatorsforsynthesizingABA,BABAB,CABAC,andothersymmetricalblockcopolymers.Sodiumnaphthalene:MMA-styrene-MMAtriblock+2s-ort- sticBlockcopolymersareinterestingbecausetheycan"microphaseseparate"toformperiodicnanostructures,asintheblockcopolymer(SBSatSt-Ip-St,St-Bd-StABAblockcopolymer(Tradenames:Cariflex,Kraton,Soloprene).Thermo elastomershavetheadvantagethattheycanbeprocessedas sticsinsteadofthermosets.Thepolymersareusedforshoesolesandadhesives.

SBSblockcopolymerschematicmicrostructureCertaincyclicmonomersforblockcopolymers:ethyleneoxide,propylenesulfide,lactams,lactones,cyclicsiloxanes echelicPolymers遙爪oneormoreendgroupswiththecapacitytoreactwithsynthesizingblockandothertypesof

2 3 36-4cCou ReactionsLivinganionicblockcopolymerscanbelinkedbycouplingCouplingreactionsallowthesynthesisofstarpolymersbyusingamultifunctionalcouplingagen