HANDBOOK OF RADICAL POLYMERIZATION Krzysztof Matyjaszewski Carnegie Mellon University, Pittsburgh, Pennsylvania Thomas P. Davis University of New South Wales, Sydney, Australia A John Wiley & Sons, Inc. Publication Coverimage:AFMimageofdenselygraftedpolystyrenebrushespreparedbyATRP.Reprintedfrom: K.L.Beers,S.G.Gaynor,K.Matyjaszewski,S.S.Sheiko,andM.Moeller,Macromolecules, 31,9413(1998). Thisbookisprintedonacid-freepaper. Copyright#2002ByJohnWileyandSons,Inc.,Hoboken.Allrightsreserved. PublishedsimultaneouslyinCanada. 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LibraryofCongressCataloging-in-PublicationDataisavailable 0-471-39274-X PrintedintheUnitedStatesofAmerica. 10987654321 CONTENTS Introduction vii KrzysztofMatyjaszewskiandThomasP.Davis Contributors xi 1 Theoryof Radical Reactions 1 JohanP.A.Heuts 2 Small Radical Chemistry 77 MartinNewcomb 3 General ChemistryofRadical Polymerization 117 BunichiroYamadaandPerB.Zetterlund 4 The Kinetics ofFreeRadical Polymerization 187 ChristopherBarner-Kowollik,PhilippVana,andThomasP.Davis 5 Copolymerization Kinetics 263 MichelleL.CooteandThomasP.Davis 6 Heterogeneous Systems 301 AlexM.vanHerkandMichaelMonteiro 7 Industrial Applications and Processes 333 MichaelCunninghamandRobinHutchinson 8 General Concepts and Historyof Living Radical Polymerization 361 KrzysztofMatyjaszewski 9 Kinetics ofLiving Radical Polymerization 407 TakeshiFukuda,AtsushiGoto,andYoshinobuTsujii 10 NitroxideMediated Living Radical Polymerization 463 CraigJ.Hawker v vi CONTENTS 11 Fundamentals of Atom TransferRadical Polymerization 523 KrzysztofMatyjaszewskiandJianhuiXia 12 ControlofFreeRadical Polymerization by Chain Transfer Methods 629 JohnChiefariandEzioRizzardo 13 ControlofStereochemistryofPolymers in Radical Polymerization 691 AkikazuMatsumoto 14 Macromolecular Engineering by Controlled Radical Polymerization 775 YvesGnanouandDanielTaton 15 Experimental Proceduresand Techniques for Radical Polymerization 845 StefanA.F.BonandDavidM.Haddleton 16 Future Outlook and Perspectives 895 KrzysztofMatyjaszewskiandThomasP.Davis Index 901 INTRODUCTION Free radical polymerization has been an important technological area for seventy years. As a synthetic process it has enabled the production of materials that have enrichedthelivesofmillionsofpeopleonadailybasis.Freeradicalpolymerization was driven by technological progress, and its commercialization often preceded scientific understanding. For example, polystyrene and poly(methyl methacrylate) wereincommercialproductionbeforemanyofthefacetsofthechainpolymeriza- tion process were understood. Theperiod 1940–1955wereparticularlyfruitfulinlayingdownthebasisofthe subject; eminent scientists such as Mayo and Walling laid the framework that still appearsinmanytextbooks.Thissuccessledsomescientistsatthetimetoconclude thatthesubjectwaslargelyunderstood.Forexample,intheprefacetoVolume3of theHighPolymersSeriesontheMechanismofPolymerReactionsin1954,Melville stated‘‘Inmanycasesitistruetosaythatthekineticsandchemistryofthereactions involvedhavebeenascompletelyelucidatedasanyotherreactioninchemistry,and there is notmuch to bewritten ordiscovered about such processes.’’ From 1955 through to 1980 scientific progress was incremental, bearing out(to some limited extent) the comments made by Melville. The ability to measure rate constants accurately was limited by scientific methods and equipment. Measuring molecular weights by light scattering and osmometry was time-consuming and did not provide a visualization of the shape of the molecular weight distribution. Techniquessuchasrotatingsectorwerelaborious,andthereweresignificantincon- sistencies among propagation and termination rate data obtained from different groups. Indeed an IUPAC working group set up under the leadership of Dr. Geoff Eastmond had great difficulty in getting agreement among experimental rate data (via dilatometry) from different laboratories. This inability to obtain accurate and consistentkineticdatahasbeenamajorimpedimenttodevelopingimprovedcontrol over conventional free radical polymerization, and has led to the cynical (though amusing) labeling of the Polymer Handbook as the ‘book of random numbers.’ Despite these difficulties, some notable progress was made in understanding the importance of diffusion control in termination reactions and in elucidating the mechanisms ofemulsionpolymerization. In the 1980s industrial and academic attention was focused on polymerization mechanismsthatofferedtheprospectofgreatercontrol,suchascationicandanionic chainreactions.Thescopeofthesereactionswasexpanded,andgrouptransferpoly- merizationwasinventedandheraldedasamajorbreakthrough.Atthattime,major investmentsinresearchandscaleupweremadebypolymerproducingcompaniesin vii viii INTRODUCTION an attempt to exploit the greater control offered by these improved ionic polymer- izations. However, the limitations of ionic processes—intolerance to functionality and impurities—proved too difficult to overcome, and free radical polymerization provedstubborntodisplaceasanindustrialprocess.Thecommercialdrivingforce behindthesearchforcontroloverthepolymerizationmechanismwastheprospect ofimprovedmaterials.Theabilitytomakespecific(bespoke)polymerarchitectures remained a powerful incentive to develop new polymerization methods. However, the lesson learned from the failure to exploitionic mechanisms was that improved controlcouldnotcomeattheexpenseofflexibility.Consequently,freeradicalpoly- merization remained dominant because it was (relatively) easy to introduce on an industrial plant, it was compatible with water, and it could accommodate a widevariety offunctional monomers. From the mid-1980s step changes in the understanding and exploitation offree radical polymerization began to occur. The mechanism of copolymerization came under scrutiny and the general failure of the terminal model was demonstrated. Advanced laser techniques were invented to probe propagation and termination rate coefficients. This ability to accurately measure rate constants led to the estab- lishment of IUPAC working parties to set benchmark kinetic values, and thus enhancedtheabilitytocreatecomputationalmodelstopredictandcontrolfreeradi- cal polymerization reactions. The cost of computation reduced substantially, and advanced modeling methods began to be applied to free radical polymerization, leading to increased understanding of the important factors governing free radical addition and transfer reactions. Alsointhe1980stheseedswerelaidforanexplosionintheexploitationoffree radical polymerization to make specific polymer architectures by using control agents. Catalytic chain transfer (using cobalt complexes) was discovered in the USSR and subsequently developed and exploited to produce functional oligomers byanumberofcompanies.TheuseofiniferterswaspioneeredinJapanandalkoxy- amines were patentedas control agentsby CSIRO. Themajorgrowthofliving(orcontrolled)freeradicalpolymerizationoccurredin the 1990s, commencing around 1994 with the exploitation of nitroxide-mediated polymerization, atom transfer radical polymerization, degenerative transfer with alkyliodides,andaddition-fragmentationtransferapproachesallowingforthefacile productionofamultitudeofpolymerarchitecturesfromsimplenarrowpolydisper- sity chains to more complex stars, combs, brushes, and dendritic structures. More- over, synthesis of block and gradient copolymers enabled preparation of many nanophaseseparated materials. This book aims to capture the explosion of progress made in free radical poly- merizationinthepast15years.Conventionalradicalpolymerization(RP)andliving radical polymerization (LRP) mechanisms receive extensive coverage together with all the other important methods of controlling aspects of radical polymeriza- tion.Toprovidecomprehensivecoveragewehaveincludedchaptersonfundamental aspects of radical reactivity and radical methods in organic synthesis, as these are highly relevant to the chemistry and physics underpinning recent developments in our understanding and exploitation of conventional and living free radical INTRODUCTION ix polymerization methods. The book concludes with a short chapter on the areas of researchandcommercialdevelopmentthatwebelievewillleadtofurtherprogress inthe near future. KRZYSZTOFMATYJASZEWSKI THOMAS P. DAVIS CONTRIBUTORS CHRISTOPHER BARNER-KOWOLLIK, School of Chemical Engineering and Industrial Chemistry, The University of New South Wales, UNSW Sydney NSW 2052, Australia STEFAN A. F. BON, Center for Supramolecular and Macromolecular Chemistry, Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom JOHNCHIEFARI, CSIROMolecularScience,Bag10,ClaytonSouth,Victoria3169, Australia MICHELLE COOTE, Room513/514, Applied Science Building, School of Chemical Engineering and Industrial Chemistry, University of New South Wales, Sydney NSW 2052, Australia MICHAEL F. CUNNINGHAM, P. Eng., Department ofChemicalEngineering, Queen’s University, Kingston, Ontario,Canada K7L 3N6 THOMAS P.DAVIS, Room513/514,AppliedScience Building,SchoolofChemical Engineering and Industrial Chemistry, University of New South Wales, Sydney NSW 2052, Australia TAKESHI FUKUDA, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011,Japan YVESGNANOU, Director,LaboratoiredeChimiedesPolymeresOrganiques,Ecole Nationale de Chimie et de Physique de Bordeaux, Ave Pey-Berland, BP108, 33402, Talence Cedex,France ATSUSHI GOTO, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011,Japan DAVIDM.HADDLETON, CenterforSupramolecularandMacromolecularChemistry, Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom CRAIG J. HAWKER, Department K17f, IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099,USA HANS HEUTS, School of Chemical Engineering and Industrial Chemistry, UniversityofNewSouth Wales, SydneyNSW 2052, Australia xi xii CONTRIBUTORS ROBIN HUTCHINSON, Department of Engineering, University of Manitoba, 344A EngineeringBldg., WinnipegR3T 5V6, Canada AKIKAZUMATSUMOTO, Department ofAppliedChemistry,FacultyofEngineering, Osaka City University, Sugimoto,Sumiyoshi-ku, Osaka 558-8585,Japan KRZYSZTOF MATYJASZEWSKI, J. C. Warner Professor of Natural Sciences, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh,PA15213, USA MICHAELMONTEIRO, EindhovenUniversityofTechnology,P.O.Box513,5600MB Eindhoven, The Netherlands MARTIN NEWCOMB, LAS Distinguished Professor, Department of Chemistry (MC 111), University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL60607-7061, USA EZIO RIZZARDO, Chief Research Scientist, CSIRO Molecular Science, Bag 10, Clayton South, Victoria 3169,Australia DANIELTATON, LaboratoiredeChimiedesPolymeresOrganiques,EcoleNationale deChimieetdePhysiquedeBordeaux,AvePey-Berland,BP108,33402,Talence Cedex,France YOSHINOBU TSUJII, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011,Japan PHILIPP VANA, University of New South Wales, School of Chemical Engineering and Industrial Chemistry, Centre for Advanced Macromolecular Design, SydneyNSW 2052, Australia ALEXM.VANHERK, EindhovenUniversityofTechnology,POBox513,5600MB Eindhoven, The Netherlands JIANHUI XIA, Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA BUNICHIRO YAMADA, Material Chemistry Laboratory, Faculty of Engineering, Osaka City University, Sugimoto,Sumiyosaka558, Japan PER BO ZETTERLUND, Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585,Japan 1 Theory of Radical Reactions JOHAN P. A. HEUTS Universityof NewSouth Wales, Sydney,Australia CONTENTS 1.1 Introduction 1.2 Classical Theories ofMonomer and RadicalReactivity 1.2.1 The Q–e Scheme 1.2.2 Patterns ofReactivity 1.2.3 BeyondClassicalTheories 1.3 Basic Transition State Theory 1.4 Basic Quantum Chemistry 1.4.1 AbInitioMolecular Orbital Theory 1.4.2 ‘‘Interactions ofthe Electrons’’ 1.4.3 Treatingaand bOrbitalsin MOTheory 1.4.4 Alternative PopularQuantumChemical Procedures 1.4.5 Pitfallsin ComputationalQuantum Chemistry 1.4.6 Practical Computational QuantumChemistry 1.5 Basic Theory ofReaction BarrierFormation 1.6 Applications inFree-Radical Polymerization 1.6.1 Radical AdditionandPropagation 1.6.2 AtomAbstraction andChain Transfer 1.7 ConcludingRemarks 1.1 INTRODUCTION Free-radical polymerization proceeds via a chain mechanism, which basically consistsoffourdifferenttypesofreactionsinvolvingfreeradicals:1(1)radicalgen- eration from nonradical species (initiation), (2) radical addition to a substituted alkene(propagation),(3)atomtransferandatomabstractionreactions(chaintrans- fer and termination by disproportionation), and (4) radical–radical recombination reactions (termination by combination). It is clear that a good process and product HandbookofRadicalPolymerization, EditedbyKrzysztofMatyjaszewskiandThomasP.Davis. ISBN0-471-39274-X. #2002JohnWiley&Sons,Inc. 1