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Polymer Physics . Wenbing Hu Polymer Physics A Molecular Approach WenbingHu DepartmentofPolymerScienceandEngineering SchoolofChemistryandChemicalEngineering NanjingUniversity Nanjing China,People’sRepublic ISBN978-3-7091-0669-3 ISBN978-3-7091-0670-9(eBook) DOI10.1007/978-3-7091-0670-9 SpringerWienHeidelbergNewYorkDordrechtLondon LibraryofCongressControlNumber:2012950781 #Springer-VerlagWien2013 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionor informationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped.Exemptedfromthislegalreservationarebriefexcerpts inconnectionwithreviewsorscholarlyanalysisormaterialsuppliedspecificallyforthepurposeofbeing enteredandexecutedonacomputersystem,forexclusiveusebythepurchaserofthework.Duplication ofthispublicationorpartsthereofispermittedonlyundertheprovisionsoftheCopyrightLawofthe Publisher’s location, in its current version, and permission for use must always be obtained from Springer.PermissionsforusemaybeobtainedthroughRightsLinkattheCopyrightClearanceCenter. ViolationsareliabletoprosecutionundertherespectiveCopyrightLaw. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexempt fromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. While the advice and information in this book are believed to be true and accurate at the date of publication,neithertheauthorsnortheeditorsnorthepublishercanacceptanylegalresponsibilityfor anyerrorsoromissionsthatmaybemade.Thepublishermakesnowarranty,expressorimplied,with respecttothematerialcontainedherein. Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Foreword There are many excellent books on polymer physics. It therefore requires some couragetowriteanewbookonthissubject.However,forthesuccessofabook,the courage of the author is less important than the novelty of the approach that the book follows and, most importantly, it is crucial that this approach addresses an existingneed. PolymerPhysics:AMolecularApproachthatProfessorWenbingHuhaswritten aimstobringsomeofthekeyconceptsofmodernpolymerphysicstoareadership that is not familiar with this field. For this target audience, the present book will providethefirst,andinsomecases,theonlyintroductiontoaverywideandactive field of research. In writing a book for this readership, Professor Hu had to make choices. Systematically, he has decided to focus on underlying physical concepts ratherthanondetailedmathematicaldescriptions,andhehastriedtohighlightthe links between the subject matter of the book and the (many) application areas. In addition,asthetitlesays,thebookusesa“molecular”picturetoexplainconcepts and phenomena. This approach has proven to be very successful for the original (Chinese)editionofthisbookanditisthereforefortunatethatthepublishershave decidedtopublishanEnglishtranslation. Ishouldaddthat,onsometopics,ProfessorHu’sbookgoeswellbeyondexisting textbooks—this is, in particular, true of Professor Hu’s own field of research: polymercrystallization,demixing,andtheinterplayofthetwo.Tomyknowledge, this is the first book that presents some of the new developments in this area of research at a level accessible to undergraduate students. Hence, the book may beofinteresttoawidercommunitythanitsoriginaltargetreadership. Cambridge DaanFrenkel March2012 v . Preface to the English Edition Polymer physics covers all the physical aspects of macromolecular substances. If weintroducedthesubjectaccordingtothecurrentclassificationsofstructuresand propertiesofpolymers,thetextbookwouldbecomethickerandthickerwiththefast expansionofourknowledge,andwouldlooklikeanencyclopedia.Suchatextbook cannot meet the current demand for a more concise introduction within a time- limited schedule of university courses on polymer-related subjects. In fact, the published textbooks on polymer physics normally selected the content according totheauthor’spersonaltasteortothespecifictrainingsubjects.Ontheotherhand, nowadays on the Internet, fragmental concepts of polymer physics are available. However, the students still need the course training on the intrinsic correlations amongmeaningfulphysicalconceptsofpolymersaswellastheusefultheoretical toolsforafundamentalanalysis.Onthebasisoftheabovechallenges,thisbookis intended to provide a concise entrance-level introduction on polymer physics. It triestoavoidthecomplicatedmathematictreatmentsofmoderntheories,thetrivial experimentaltechniques,thedetailsofpracticalindustrialprocessing,andthewide applications of polymers. Rather, the attention is only focused on three basic aspects of comprehensive principles of polymer physics, including molecular structures, molecular motions, and phase transitions, in order to elaborate the basicstatisticalthermodynamicsandkinetics(themean-fieldtheoryandthescaling analysis)aswellastheirstate-of-the-artapplications.Thebookmayhelpreadersto establishseveralkeymolecular-levelpicturesofpolymerphysics.Thebooktargets seniorundergraduatestudents,graduatestudents,teachers,andresearchers,whoare studying and working in the extensive fields of physical sciences, life sciences, materials sciences, and engineering sciences relevant to physical aspects of polymers.Throughasystematicstudy,thereadersareexpectedtograspthebasic concepts of polymer physics as well as the theoretical tools for a fundamental analysisofmacromolecules. The current English edition was basically translated from its recent Chinese version(SciencePublisherinBeijing,2011),withminorexpansiononthehistorical aspectsofsomefundamentalideasandtheiroriginalreferences.Aftertheintroduc- tory chapter, the book has been split into three parts: chain structures, chain vii viii PrefacetotheEnglishEdition motions, and chain assembly. The first part introduces the relationships between chemicalstructuresofpolymersandtheirphysicalbehaviors,theGaussianstatistics of ideal-chain conformation, the derivation of the equation of state for ideal rubbers, as well as the scaling analysis of some non-ideal-chain conformations (polymer solutions, polyelectrolyte, stretching, and spatialconfinement). The sec- ondpartintroducesthescalinganalysisofchaindynamics,therelaxationbehaviors ofpolymerdeformation,andtheviscoelasticbehaviorsofpolymerflows.Thethird partintroducespolymerassemblyviaphasetransitions,whichincludesthestatisti- calthermodynamicsofpolymersolutions(Flory-Hugginsmean-fieldlatticetheory and its developments), phase separation (its thermodynamics and kinetics; in addition,microphaseseparationofblockcopolymers),andpolymercrystallization (thermodynamics, kinetics, and morphologies). The book ends with an extended readingmaterialontheinterplayofphaseseparationandcrystallizationinpolymer- based multi-component systems. Each chapter is complemented at the end with severalquestionsetstohighlightsomebasicideas. The delivery of this English edition was decided in a nice conversation with Dr. Stephen Soehnlen, the Springer editor. Prof. Daan Frenkel offered a perfect foreword.Prof.YifuDingandDr.RanNimadeathoroughproofreadingoverthe original text, and Prof. An-Chang Shi and Dr. Jamie Hobbs made separate proofreading on the first and second chapters. With their great help, the present bookbecamemorereadableasatextbook! Thecontentofthisbookislimitedbytheauthor’sacademicbackgroundaswell as by the pedagogic style of a textbook. It could not completely cover all the important academic ideas in the related fields or all the original references in the historical aspects. The author is mainly reponsible for any mistakes in the text.Friendlysuggestionsandcommentsarealwaysmostwelcome! Nanjing WenbingHu July,2012 Contents 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 WhatArePolymers?. . . . . .. . . . . . . . . . . .. . . . . . . . . . . . .. . 1 1.2 PolymersintheEyesofPhysicists. . . . . . . . .. . . . . . . . . . . .. . 3 1.3 RoleofPolymerPhysics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.4 FocusingofthisBook. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 PartI ChainStructure 2 Structure–PropertyRelationships. . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.1 CharacterizationofChemicalStructures. . . . . . . . . . . . . . . . . . 13 2.2 Semi-FlexibilityofPolymerChains. . . . . . . . . . . . . . . . . . . . . . 14 2.2.1 FreelyJointedChains. . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.2.2 FreelyRotatingChains. . . . . . . . . . . . . . . . . . . . . . . . . 16 2.2.3 HinderedRotatingChains. . . . . . . . . . . . . . . . . . . . . . . 17 2.2.4 CharacterizationofStaticSemi-Flexibility ofPolymers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.3 LocalInter-ChainInteractions. . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.4 MolecularWeightsandTheirDistributions. . . . . . . . . . . . . . . . 23 2.4.1 MolecularWeightEffects. . . . . . . . . . . . . . . . . . . . . . . 23 2.4.2 CharacterizationofMolecularWeights. . . . . . . . . . . . . . 24 2.5 TopologicalArchitectures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.6 SequenceIrregularities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.6.1 ChemicalIrregularities. . . .. . . . . . . . . .. . . . . . . . . .. . 30 2.6.2 GeometricalIrregularities. . .. . . . .. . . . .. . . . .. . . . .. 30 2.6.3 SpatialIrregularities. . . . . . . . . . . . . . . . . . . . . . . . . . . 31 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 ix