考研浙大报考高化1ionic chain polymn

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

C

STABILIZATIONOFSUBSTITUENTSRCTheionicpolymerizationhasaverystrictrequirementsforstabilizationofR++4FIG1.Resonanceandstabilityofionicpropagating5烯烃中唯一能子聚合的6丙烯 甲基丙烯酰 苯乙 322327661b大多数离子聚合包括两种类型的增长种：离子对和自由离子它们共存于平衡中。紧密离子对(2)和溶剂分子对(3)的比例依溶剂性质对离子聚合的影响极其显著，因为不同类型的增长种具不同于自由基聚合，在离子聚合中不会发生增长链之间的双分子8c的活性种（离子）极性溶剂（水、醇）：破坏离子酮：与剂形成稳定的络合低极性或中等极性溶剂：CH3(CH2)3CH3,CCl4,CH3Cl,ClCH2CH2Cl,PhNO2,etc.大多数子聚合反应的剂为非均相无机物，对杂聚合机理聚合机理3 3 LewisMetalhalides:AlCl3,BF3,SnCl4,SbCl5,ZnCl2,TiCl4,PCl5Organometalliccompounds:RAlCl2,R2AlCl,

酸是最重要的用于子聚合的剂。其中，AlCl3已在工业上广Oxyhalides:POCl3,

泛应用 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，一级和二级卤代烃不能用作子聚合的有效剂。通常，一级和二级卤代烃不能用作子聚合的有效剂。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向单体的链转移常数：向单体的链转移常数：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+自发终止：增长离子对发生重排导致链终止，形成带不饱和端基 自发终止亦称向反离子转移，在动力学上不同于向单体转移；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链转移剂（chain-transferagents：溶剂、杂质或有意添加到反应体系Althoughachain-transferagentdecreasesthedegreeofpolymerizationinproportiontoitsconcentration,itisnotexpectedtoaffectthepolymerizationratesincetheinitiator-coinitiatorcomplexshouldberegeneratedontransfer.聚合度下降，聚合速率未必下降。Often,water,alcohol,ammonia,andaminesusedinexcess6-2b. Kinetic假设聚合机理由式Eq.6-1a、6-1b，Eq.6-2和6-5组成，即终止方式为稳态假定：采用类似于自由基聚合动力学推导的稳态条件（Ri 除了“增长中心与反离子结合”外，当链终止反应还同时包括“向单体链转移”(Eq.6-3)、“自发终止”(Eq.6-4)和“向链转移剂(S)少而不致于使剂失活）。但是，这些链终止使聚合度下降。 =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+ 如果在过程中，剂-共剂络合物的形成反应(Eq.6-1a)是决速步骤，则速率不依赖于单体浓度：Eq.6-17。速率表.

p[M]Ri= (6- Kinetic子连锁聚合反应各种速率常数(kikpktktsktr)的测定并非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一般说来，具有较大kp的单体，CM较小。CM101~102，比自由单体聚合活性次序:乙烯基醚>异丁烯>苯乙烯>异戊 TABLE4.Chain-transferconstantsforsome(CS)instyreneInitiatoror CS102 0含有易解离的负电荷碎片（如甲醇中的CH3O）随剂、共剂或溶剂种类的改变，同一链转移剂的链转移c.影响子聚合的因溶剂效应SolventEffects 溶剂极性影响自由离子和离子对TABLE5.Effectofsolventonolmerizationofp-methoxstrene I2atCH2Cl2/CCl4CH2Cl2/CCl4kpapp

溶剂能改变不同增长物种的增长速率常数，从而影响聚合速率和聚Thekpappincreasesbymorethan2ordersofmagnitudeingoingCCl4(=2.24)toCH2Cl2(=9.08).Specificsolvationandpolarizationeffectsmaybeimportantinaparticularsystem. 反离子效应CounterionTABLE6. olkpapp,Liters/mole-

及-键到-键不论方式，，ER–20~40NOTE:负的ER并非意味着达到过渡态只需负的活化能。任何基元反应的活化能都为正值。R值为负只表明t大于(i+p).Temp.tRp聚合度综合活化能：Exn–12.5~–29聚合度综合活化能总是负值，因为不论链终止方式如何，Et或通常大于Ep。提高温度更有利于加快终止或链转移速率，因此， nFig.3TemperaturedependenceofXnforthealuminumchloride(AlCl3)polymerizationof

显改变，对应于Exn=–23.4–3.1kJ/mole。表明随温度变化，链终止方式由向单体链转移（低于–100℃）100℃）。这种Exn转变也可（至少部份）归因于温度对不同类型增长物种相对比例的影响 Commercialapplicationsofcationicpolymerization 聚异丁烯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在阴离子聚合中，增长物种是离子对（anionicionpair）和自由阴离子（ions），两者的相对浓度如同子聚合一样依赖于反与子聚合不同，在阴离子聚合中离子对和自由阴离子的活性尽管阴离子聚合通常在低温下快速进行，但很少像 子聚合那样对温度敏感；绝大多数阴离子聚合反应具有正的活化能（ER），可在常温或略高于常温下进行。溶剂：脂肪族和芳香族烃、醚。卤代溶剂、极性溶剂（酯和酮）剂Nucleophilic剂Nucleophilic亲核试剂（B:orB:）：NaNH2、LiN(C2H5)2（Alkoxide）、氢氧化物、化物（Cyanides）、膦、胺、n-C4H9Li,、PhMgBr等。compoundsareprobablythemostusefuloftheseinitiatorsduetotheirgoodsolubilityin电子转移ElectronTransferOverberger

Li/NH3

+

LiNH2/NH3 asolvated 电子转移也可发生在非均相聚合中，过程包括碱金属在单体乙SrR2,Na,RNaLi,RLi

t-

strongweakbases

2CH(CH3)CN

Theinitiatorrequiredtopolymerizeamonomerdependsonthe PolymerizationWithout 整聚合过程中，增长中心（碳负离子）有的色保不变，即使单体转化率达到100％其颜色也不 或改变达到100 TransferAgents(H2O,O2,CO2,ROH,etc.) Spontaneous

聚苯乙烯阴离子在活性阴离子体系中最为稳定，在CH2CH-CH2-C:-CH2CH-CH2-C:-Na+HCH2-C:- CH2CH- CH2-CH2Ph CH2C-

烃类溶剂中可存活数周。 1,3-diphenylally括对-H的夺取和/或对CO括对-H的夺取和/或对CO键的进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讨论Eq.6-17适用于速率比增长速率快的情形。这个条件在极性溶改进的膨胀计测定技术：将毛细管内的反应物流入含有终止剂的溶剂中来终止聚合反应，通过定量分析被淬灭的反应混合物（聚合物或未反应单体）来获得转化率、Rp和kpapp.Themajordifferenceintheratesofanionicandradicalpolymerizationsresidesinthelackofterminationinanionicpolymerizationandthelargedifferenceintheconcentrationsofthepropagatingspecies.DegreeDegreeof于为消耗的单体浓度与活性端假定通常的情形：所有的引发剂I全部转变为增长活性对于快速、高效混合的活性阴离子聚合体系（不存在降解、终止和EffectsofReactionTABLE7.Effectofsolventonanionicpolymerizationofconstant()253**Sodiumnaphthalene(310-3mole/L),表观速率常数kpapp随反应介质溶剂化能力的提高，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来提供，如：加入NaBPh4可提供过量的Na+）。[P]=因为外加盐容易解离，而离子对解离倾向很小，则反离子浓度非常接近外加盐的浓度[CZ]:[C+]则：自由阴离子的浓度:[P离子对的浓度:[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自由离子的反应活性比离子对大102~103。K值变化趋势与反离子的溶剂化程度一致。K值变化会显著影响高活性自由LiCs，这是因为溶剂分子对所占分数随反离子溶剂化程度对于二氧六环体系，得不到Kkp数据。(kp±)Dioxane<(kp±)THF，且变化趋势与THF体系相反。在二氧六环中，较活泼的溶剂分子对所占分数较小；高活性的离子对是那些与反离子弱键合的离子对 温度的影响.溶剂分子对和紧密离子对的反应活 ER=37.6kJ/molindioxane;4.2kJ/molin温度对增长反应速率的影响比较复杂Temp., ,kpKP子对与自由Table9.ProaationofsodiuminTHFat20Col子对与自由Table9.ProaationofsodiuminTHFat20Colstr这表明溶剂分1.31.3 24liters/mole-5.5 ..1,溶剂分子对的活性不易受反离子的影响。SeekpinTHF(Tab.8)..AssociationPhenomenainAcomplicationforpolymerizationinitiatedbyRLiinnonpolarsolventsisassociation(aggregation)ofthevariousorganolithiumspeciespresentinthereactionsystem.Thefractionalkineticordersonlymonomericinitiatorandpropagatingionpairsarereactive.PolymerizationinaliphatichydrocarbonsisconsiderablythaninaromaticTheassociationphenomenaoccurringwithalkyllithiuminitiatorsinnonpolarsolventsresultsinverylowpolymerization18-crown- Block6-4aSequentialMonomerSequentialadditionofmonomerstoalivinganionicpolymerizationsystemisatpresentthemostusefulmethodofsynthesizingwell-definedblockcopolymers.Thepropersequencingofadditionsofdifferentmonomers.Forexample:(St-b-MMA)copolymer. PS的碱性比PMMA强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遥爪oneormoreendgroupswiththecapacitytoreactwithsynthesizingblockandothertypesof

2 3 36-4cCou ReactionsLivinganionicblockcopolymerscanbelinkedbycouplingCouplingreactionsallowthesynthesisofstarpolymersbyusingamultifunctionalcouplingagen