Fundamentals of Controlled/Living Radical Polymerization 1 0 0 P F 5- 2 4 7 3 7 9 4 8 1 8 7 9 9/ 3 0 1 0. 1 oi: d g | or c. s s.r b u p p:// htt n o 3 d 01 e2 nloadApril Down 25 o d e h s bli u P View Online RSC Polymer Chemistry Series Series Editors: Professor Ben Zhong Tang (Editor-in-Chief), The Hong Kong University of Science and Technology, Hong Kong, China 1 Professor Alaa S. Abd-El-Aziz, University of Prince Edward Island, Canada 0 P0 Professor Stephen L. Craig, Duke University, USA F 5- ProfessorJianhua Dong,NationalNaturalScience FoundationofChina,China 2 4 Professor Toshio Masuda, Fukui University of Technology, Japan 7 3 7 Professor Christoph Weder, University of Fribourg, Switzerland 9 4 8 1 8 7 Titles in the Series: 9 39/ 1: Renewable Resources for Functional Polymers and Biomaterials 0 0.1 2:Molecular Design and Applications of Photofunctional Polymers and oi:1 Materials d 3: Functional Polymers for Nanomedicine org | 4: Fundamentals of Controlled/Living Radical Polymerization c. s s.r b u p p:// htt n o 3 d 01 e2 nloadApril Down 25 o d e h s bli u P How to obtain future titles on publication: A standing order plan is available for this series. A standing order will bring delivery of each new volume immediately on publication. For further information please contact: BookSalesDepartment,RoyalSocietyofChemistry,ThomasGrahamHouse, Science Park, Milton Road, Cambridge, CB4 0WF, UK Telephone: +44(0)1223 420066,Fax:+44(0)1223420247 Email:[email protected] Visit our website atwww.rsc.org/books View Online Fundamentals of Controlled/ Living Radical Polymerization 1 0 0 P F 5- 2 4 7 Edited by 3 7 9 4 8 81 Nicolay V Tsarevsky 7 9 9/ Department of Chemistry, Southern Methodist University, Dallas, TX, USA 3 10 Email: [email protected] 0. 1 oi: d g | Brent S Sumerlin c.or Department of Chemistry, University of Florida, Gainesville, FL, USA s s.r Email: [email protected]fl.edu b u p p:// htt n o 3 d 01 e2 nloadApril Down 25 o d e h s bli u P View Online 1 0 0 P F 5- 2 4 7 3 7 9 4 8 1 8 7 9 9/ 3 0 1 0. 1 oi: d g | or c. s s.r b u p p:// RSCPolymerChemistrySeriesNo.4 htt n ISBN: 978-1-84973-425-7 o 3 ISSN: 2044-0790 d 01 e2 nloadApril AcataloguerecordforthisbookisavailablefromtheBritishLibrary Down 25 rTheRoyalSocietyofChemistry2013 o d Allrightsreserved e h s bli Apartfromfairdealingforthepurposesofresearchfornon-commercialpurposesorfor u P privatestudy,criticismorreview,aspermittedundertheCopyright,DesignsandPatents Act1988andtheCopyrightandRelatedRightsRegulations2003,thispublicationmaynot bereproduced,storedortransmitted,inanyformorbyanymeans,withouttheprior permissioninwritingofTheRoyalSocietyofChemistry,orinthecaseofreproductionin accordancewiththetermsoflicencesissuedbytheCopyrightLicensingAgencyintheUK, orinaccordancewiththetermsofthelicencesissuedbytheappropriateReproduction RightsOrganizationoutsidetheUK.Enquiriesconcerningreproductionoutsidethe termsstatedhereshouldbesenttoTheRoyalSocietyofChemistryattheaddressprinted onthispage. TheRSCisnotresponsibleforindividualopinionsexpressedinthiswork. PublishedbyTheRoyalSocietyofChemistry, ThomasGrahamHouse,SciencePark,MiltonRoad, CambridgeCB40WF,UK RegisteredCharityNumber207890 Forfurtherinformationseeourwebsiteatwww.rsc.org PrintedintheUnitedKingdombyHenryLingLimited,Dorchester,DT11HD,UK 5 0 0 P F Preface 5- 2 4 7 3 7 9 4 8 1 8 7 9 9/ 3 0 0.1 There is little doubt the advent of controlled/living radical polymerization 1 oi: (CRP) has revolutionized modern polymer science. Perhaps more than any d g | syntheticdevelopmentofthelastseveraldecades,CRPhasunlockedaccesstoa or plethora of new functional and well-defined polymers to address a variety of c. s.rs complexapplications.Previouslyconsideredusefulforprimarilythefacileand ub rapid preparation of high molecular weight polymers for mostly commodity p p:// applications, radical polymerization can now be readily employed to prepare htt specialtymaterialsbasedon(co)polymersthatarewell-defined,havecontrolled n 3 o molecular weights and end group functionality, complex topologies, and d 01 predefined segment sequences (e.g., block copolymers). e2 Downloadn 25 April tphoaMlytmocroeernittzrhaoatlinsonaitnshyapdortohbpeeeerrntciheesamrapanclotdeyrepidsottifceo,nrtitimailsanuthytielyitmeya.orlsWecthouillaaerchcwioeenvivgeehhntitgoiohfnamalpoorlealycdumiclaearrl o d weight polymers, precise control of chain length remained difficult. External e sh chaintransferagentsprovedusefultolimitmolecularweights,buttheobtained bli u polymers were characterized with broad molecular weight distributions. The P diverse family of CRP techniques developed over the last 2–3 decades now allows access to polymers of a specific chain length that can be derived from virtually any vinyl monomer polymerizable by a radical method. Conventional radical polymerization had limited success in the preparation of polymers with specific chain-end functional and/or reactive groups. Although certain functionalized radical initiators showed some potential, the rangeoffunctionalgroupsthatcouldbeattachedefficientlytoeitherendofthe macromolecules was relatively narrow. Further, due to the ever-present terminationandtransferreactions,whichrapidly‘‘kill’’thepropagatingchains, itisvirtuallyimpossibletopreparesamplesinwhichnearlyallmacromolecules arechain-end-labeled.Incontrast,CRPmethodshaveprovedverypowerfulin the synthesis of polymers containing either identical or different a- and RSCPolymerChemistrySeriesNo.4 FundamentalsofControlled/LivingRadicalPolymerization EditedbyNicolayVTsarevskyandBrentSSumerlin rTheRoyalSocietyofChemistry2013 PublishedbytheRoyalSocietyofChemistry,www.rsc.org v View Online vi Preface o-chain-endfunctionalgroups.ThesynthesisofcompositematerialsbyCRPis also straightforward. Oneofthekeybenefitsofclassicalradicalpolymerizationisthefacilitywith which many monomers can be incorporated into a single chain by copoly- merization. Depending on the relative reactivity of the comonomers, random, 05 alternatingandblockysequencescanbeachieved.However,blockcopolymers 0 FP with well-defined junction points linking segments of differing repeat units are 5- 2 nearly impossible to prepare directly by conventional radical polymerization. 4 7 3 While it was possible to prepare block copolymers by coupling two end- 7 9 4 functional homopolymers or by polymerization from homopolymers 8 81 terminatedwithamoietythatallowedasubsequentpolymerizationstep,facile 7 9/9 access to block copolymers was not achieved by a radical mechanism prior to 3 0 the development of controlled radical methods. Since then, an enormous 1 10. number of new block copolymers have been prepared by CRP, and this has doi: provided access to a variety of new materials with potential applications as g | drug delivery agents, cosmetics, coatings, adhesives, thermoplastic elastomers, or c. etc.Additionally,thecopolymerizationofmonomerswithdifferentreactivities s bs.r under CRP conditions yields gradient copolymers, in which the composition u http://p cishtahnegecsasaeloinngcothnevepnotliyomnaerl rbaadcikcbaolnpeo,lyinmseteraizdatoiofnfr)o.mGroandeiecnhtacinoptoolyamnoetrhsewre(ares n inaccessiblethroughtraditionalradicalpolymerizationandareverypromising o d 013 materials in various fields, such as surfactants, degradable polymers, etc. nloadeApril 2 is cAhnaointhaerrcahsipteeccttuorfe.chBayinemstprulocytuinregtnheawthinasitbiaetcoorms oermroerveerrseiabdleilychmaainnitpruanlastfeedr Dowon 25 acogmenptslewxiathrcmhiuteltcitpulreessitpersecvaiopuasbllye coofninsiidtiearteindginchacacinesgsirbolwetcha,nanwoiwdebvearrieeatydiolyf d he prepared by CRP. Stars, combs, and brushes represent only a fraction of s bli branchedchaintopologiesthathavebeensynthesized.ThisaspectofCRPhas u P enabledbothnewapplicationsandfundamentalinsightintopolymerstructure- property relationships. Many of the aforementioned characteristics of CRP are in common with those of previously developed (pseudo)living ionic polymerization techniques. However, it is the relative ease with which CRP can be employed to achieve these characteristics that has led to the continued success and growth of the field.Indeed,becausemostofthemethodsdescribedinthechaptersthatfollow can be conducted under relatively non-stringent conditions in a variety of solventsandatawiderangeoftemperatures,thebarriertoentrytothefieldis minimal. Precision polymer synthesis is now possible in laboratories without access to expensive experimental equipment or extensive expertise. It is important to remember that the CRP techniques are based on the success achieved over many years in the areas of living ionic polymerizations. ThesuccessofSzwarcandothersinrecognizingthefar-reachingutilityofliving anionic polymerization led many to pursue the goal of polymerization control during other chain growth methods. Molecular weight and end group control in cationic polymerization was subsequently achieved by introduction of the concept of dormant-active equilibration (i.e., ‘‘reversible deactivation’’) that View Online Preface vii kinetically limited the extent of chain breaking reactions by rendering a significant fraction of chains dormant at any given time. Unfortunately, ionic polymerizations are applicable only to a relatively narrow range of monomers and required stringent reaction conditions (e.g., absence of moisture, carbon dioxide, and many other impurities often encountered in commercially 05 available monomers and solvents). Owing to significant differences in the 0 FP reactivity ratios of the ionically polymerizable monomers, copolymerization 5- 2 reactionsareoftenchallenging,whichlimitsthenumberofaccessiblematerials. 4 7 3 For a relatively long time, it was considered that radical polymerizations that 7 9 4 were living or atleastresembledlivingionic processwereimpossibletodesign 8 81 due to fast termination reactions between the propagating radicals. It was 7 9/9 thought that living radical polymerization could only be achieved in system 3 0 where the mobility of the growing radicals was drastically diminished by, for 1 10. instance,carryingoutthepolymerizationsinveryviscousmediaandpreferably doi: atlowtemperatures(which notonlyincreasestheviscositybutalso minimizes g | transfer). Of course, such approaches were not particularly practical. The or c. principle of reversible deactivation of propagating radicals was extended to s bs.r radical polymerization in the 1980s and proved to be of tremendous utility in u http://p tchheemdiesstrigynemofplloivyiendg-tloikeacrhaiedvicealrepveorlsyimbleeridzaeaticotnivsa.tiIotnisthtahtedsiffpeerceifinctsiatoefs tthhee n various CRP processes. The fundamental aspects such as kinetics, thermo- o d 013 dynamics, structure-reactivity correlations, solvent effects, etc., of the most nloadeApril 2 inmopteodrttahnattCraRdPicamleptohloydmsearirzeatthioenssuabrjeecnteovefrchtrauplytelrisviinngth(tiesrmboinoakt.ioItnsrheoaucltdiobnes Dowon 25 ashlwoawymstaankyeopflathcee),chbaurtaucstienrgisttihcesroefvleivrsinibglepodleyamcteivriaztaiotinonstsr,astuecghy,atshceosnetrreoalcotivoenr d he molecular weight (determined by the ratio of monomer to initiator), narrow s bli molecular weight distribution (if initiation is fast), high degree of chain-end u P functionalization, which is responsible for the ability to synthesize block copolymers, etc. Owing to the ability to control numerous molecular parameters and due to the fact that radical polymerizations with reversible deactivationresemblecloselytheclassicallivingionicpolymerizations,wehave adopted the term controlled/living radical polymerization in this book. WehopethisbookprovidesinsightintothecurrentstateoftheartinCRPwhile also giving historical perspective to the field. While many other books have focusedoncontrolled/livingpolymerizations,includingCRP,andhaveprovided extensiveinsightintothematerialsthatcanbepreparedtherefrom,ourintenthere is to elucidate the fundamentals governing the most common types of CRP. In many cases, particular attention is dedicated to the kinetic and thermodynamic factorsthateffectpolymerizationcontrol.Wehopethiscollectionwillbeusefulto bothexpertsandnewcomerstothisrapidlyexpandingfield. Nicolay V. Tsarevsky Southern Methodist University, Dallas Brent S. Sumerlin University of Florida View Online 5 0 0 P F 5- 2 4 7 3 7 9 4 8 1 8 7 9 9/ 3 0 1 0. 1 oi: d g | or c. s s.r b u p p:// htt n o 3 d 01 e2 nloadApril Down 25 o d e h s bli u P 9 0 0 P F Contents 5- 2 4 7 3 7 9 4 8 1 8 7 9 9/ Chapter 1 Kinetics and Thermodynamics of Radical Polymerization 1 3 10 F. Ehlers, J. Barth and P. Vana 0. 1 oi: d 1.1 Introduction 1 org | 1.2 Initiation 2 sc. 1.2.1 Thermal Initiation 4 bs.r 1.2.2 Photoinitiation 4 u p p:// 1.2.3 Self-initiation 7 htt 1.2.4 Redox-initiation 8 on 1.3 Propagation 8 3 d 01 1.3.1 Chain Length Dependence 9 e2 nloadApril 11..33..23 MSoolvneonmteErffEecfftescts 129 Down 25 1.4 Transfer 14 o 1.4.1 Transfer to Monomer 15 d he 1.4.2 Transfer to Initiator 17 s bli 1.4.3 Transfer to Solvents or Transfer Agents 17 u P 1.4.4 Transfer to Polymer 22 1.5 Termination 25 1.5.1 Combination versus Disproportionation 25 1.5.2 Termination Rate 28 1.5.3 Monomer Conversion Dependence 29 1.5.4 Chain-lengthDependentTermination(CLD-T) 31 1.5.5 Combined Chain-Length and Monomer Conversion Dependence 35 1.5.6 Temperature and Pressure Dependence 36 1.5.7 Solvent Effects 37 RSCPolymerChemistrySeriesNo.4 FundamentalsofControlled/LivingRadicalPolymerization EditedbyNicolayVTsarevskyandBrentSSumerlin rTheRoyalSocietyofChemistry2013 PublishedbytheRoyalSocietyofChemistry,www.rsc.org ix View Online x Contents 1.6 Rate of Polymerization 38 1.7 The Chain Length Distribution 42 1.8 Thermodynamics 48 References 51 09 Chapter 2 Fundamental Aspects of Living Polymerization 60 0 FP Robson F. Storey 5- 2 4 7 3 2.1 Introduction 60 7 9 4 2.2 DiagnosticCriteriaforLivingnessofPolymerizations 61 8 81 2.3 Quantifying Degree of Livingness 63 7 9/9 2.4 Types of Living Systems 64 3 0 2.5 Propagation Kinetics of Reversible-Deactivation 1 0. 1 Polymerizations 65 oi: d 2.6 ChainBreaking ReactionsinReversible-Deactivation org | Polymerizations 67 sc. 2.7 Rate of Initiation 70 bs.r 2.8 Polydispersity of Living Polymers 71 u p p:// 2.9 Shelf Life of Living Polymerizations 74 htt 2.10 Conclusion 75 on References 75 3 d 01 e2 nloadApril Chapter 3 CofoInntirfoelrlteedr/sLiving Radical Polymerization in the Presence 78 Down 25 Mehmet Atilla Tasdelen and Yusuf Yagci o d e h 3.1 Introduction 78 s bli 3.2 Kinetics 79 u P 3.3 Iniferters 84 3.3.1 Thermal Iniferters 84 3.3.2 Photoiniferters 87 3.3.3 Redox Iniferters 88 3.4 Applications 92 3.4.1 Telechelic Polymers by Iniferters 92 3.4.2 Complex Macromolecular Architectures by Iniferters 92 3.4.4 Surface Modification by Iniferters 98 3.5 Conclusions 101 Abbreviations 102 References 103 Chapter 4 Controlled/Living Radical Polymerization Mediated by Stable Organic Radicals 112 Peter Nesvadba 4.1 Introduction 112