Sepour/Carraher's Polymer Chemistry Sixth Edition Revised and Expanded
Charles E. Carraher, Jr. College of Science Florida Atlantic University Boca Raton, and Florida Center for Environmental Studies Palm Beach Gardens, Florida, U.S.A.
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Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. UNDERGRADUATE CHEMISTRY
A Series of Textbooks
Edited by
J. J. LAGOWSKI Department of Chemistry The University of Texas at Austin
1. Modern Inorganic Chemistry, J. J. Lagowski 2. Modern Chemical Analysis and Instrumentation, Harold F. Walton and Jorge Reyes 3. Problems in Chemistry, Second Edition, Revised and Expanded, Henry O. Daley, Jr., and Robert F. O'Malley 4 Principles of Colloid and Surface Chemistry, Paul C. Hiemenz 5. Principles of Solution and Solubility, Kozo Shinoda, translated in collaboration with Paul Becher 6. Physical Chemistry: A Step-by-Step Approach, M. K. Kemp 7. Numerical Methods in Chemistry, K. Jeffrey Johnson 8. Polymer Chemistry An Introduction, Raymond B. Seymour and Charles E. Carraher, Jr 9. Principles of Colloid and Surface Chemistry, Second Edition, Revised and Expanded, Paul C. Hiemenz 10. Problems in Chemistry, Second Edition, Revised and Expanded, Henry O. Daley, Jr, and Robert F. O'Malley 11. Polymer Chemistry: An Introduction, Second Edition, Raymond B. Seymour and Charles E. Carraher, Jr 12. Polymer Chemistry. An Introduction, Third Edition, Revised and Expanded, Raymond B. Seymour and Charles E. Carraher, Jr. 13. Seymour/Carraher's Polymer Chemistry: An Introduction, Fourth Edition, Revised and Expanded, Charles E. Carraher, Jr. 14. Seymour/Carraher's Polymer Chemistry: Fifth Edition, Revised and Expanded, Charles E. Carraher, Jr. 15. Principles of Thermodynamics, Myron Kaufman 16. Seymour/Carraher's Polymer Chemistry: Sixth Edition, Revised and Expanded, Charles E Carraher, Jr.
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Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. To Raymond Seymour—educator, scientist, pioneer, prophet, historian, family man, and friend—we miss you
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Foreword
Polymer science and technology has developed tremendously over the last few decades, and the production of polymers and plastics products has increased at a remarkable pace. By the end of 2000, nearly 200 million tons per year of plastic materials were produced worldwide (about 2% of the wood used, and nearly 5% of the oil harvested) to fulfill the ever-growing needs of the plastic age; in the industrialized world plastic materials are used at a rate of nearly 100 kg per person per year. Plastic materials with over $250 billion dollars per year contribute about 4% to the gross domestic product in the United States. Plastics have no counterpart in other materials in terms of weight, ease of fabrication, efficient utilization, and economics. It is no wonder that the demand and the need for teaching in polymer science and technology have increased rapidly. To teach polymer science, a readable and up-to-date introductory textbook is required that covers the entire field of polymer science, engineer- ing, technology, and the commercial aspect of the field. This goal has been achieved in Carraher’s textbook. It is eminently useful for teaching polymer science in departments of chemistry, chemical engineering, and material science, and also for teaching polymer science and technology in polymer science institutes, which concentrate entirely on the science and technologies of polymers. This sixth edition addresses the important subject of polymer science and technology, with emphasis on making it understandable to students. The book is ideally suited not only for graduate courses but also for an undergraduate curriculum. It has not become more voluminous simply by the addition of information—in each edition less important subjects have been removed and more important issues introduced. Polymer science and technology is not only a fundamental science but also important from the industrial and commercial point of view. The author has interwoven discussion of these subjects with the basics in polymer science and technology. Testimony to the high acceptance of this book is that early demand required reprinting and updating of each
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. of the previous editions. We see the result in this new significantly changed and improved edition.
Otto Vogl Herman F. Mark Professor Emeritus Department of Polymer Science and Engineering University of Massachusetts Amherst, Massachusetts
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Preface
An explosive scientific and technological revolution is underway and at its center are polymers. This revolution is the result of a number of factors that complement one another. These factors include a better understanding of the science of materials and availability of new and refined materials, synthetic techniques, and analytical tools. Much of this revolution is of a fundamental nature and it is explored in the latest edition of this text. These advances are often based on new and extended understanding and application of basic principles initially presented in the core chemistry courses (organic, physical, inor- ganic, analytical, and biological). Polymer Chemistry complies with the advanced course definition given by the Amer- ican Chemical Society Committee on Professional Training, building on the foundations laid in general, organic, physical, analytical/instrumentation, and inorganic chemistry. It also includes all the major and optional topics recommended in the syllabus adopted by the joint polymer education committee of the American Chemical Society (Appendix D: Syllabus). The text integrates and interweaves the important core topic areas. The core topics are interrelated with information that focuses on polymer topics. This assists students in integrating their chemical knowledge and illustrates the connection between theoretical and applied chemical information. Also, industrial practices and testing procedures and results are integrated with the theoretical treatment of the various topics, allowing the reader to bridge the gap between industrial practice and the classroom. It is written so that chapters can be taken out of order and not all the chapters need to be covered to gain an adequate appreciation of the science of polymers. Many of the chapters begin with theory, followed by application. Some readers will elect to read the more descriptive chapters dealing with polymer types before looking at the analytical/analysis/properties chapters. This book is user friendly—it is appropriate as an advanced undergraduate text or an introductory-level graduate-level course text. It can serve as the text for the initial
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. course in a series taken by a student, or it can be the lone polymer text read by a student in the study of polymers. Students of chemistry, materials, engineering, medicine, biochem- istry, physics, and geology will benefit from an understanding of the material found in this text. The application and theory of polymers continues to expand. This new edition re- flects this growth and the continually expanding role of polymers. There is an increased emphasis on pictorializing, reinforcing, integrating, and interweaving the basic concepts. The first chapter is shorter in order to allow time for student orientation. However, the other chapters should not require more than a week’s time each. Each chapter is essentially self-contained, but each relates to the other chapters. Whenever possible, diffi- cult concepts are distributed and reinforced over several chapters. A glossary, biography, suggested questions (and answers), and learning objectives/summary are included at the end of each chapter. Application and theory are integrated so that they reinforce one another. This is true for all the various important and critical types of polymers including synthetic, biological, organometallic, and inorganic polymers. The principle that the basic concepts that apply to one grouping of polymers apply to all the other types of polymers is emphasized. The updating of analytical, physical, and spectral characterization techniques contin- ues, including expanded coverage of the theory and results arising from atomic force microscopy and scanning probe microscopy. Special sections dealing with industrially important polymers are included, and the section dealing with soluble stereoregulating catalysis has been expanded. There is still an emphasis on naturally occurring polymers, and discussions of supercoiling, replication, and compacting are included. As before, the interplay between natural and synthetic polymers is emphasized. A number of miscellaneous topics have been drawn together in one chapter, which includes sections on conductive polymers, smart materials, protomics, human genome, optical fibers, material selection charts, carbon nanotubes, and liquid crystals. Emphasis on nanotechnology and nanomaterials remains with added or expanded sections dealing with zeolites, nanotubes, nanocomposites, molecular wires, dendrites, and self assembly. The chapter on polymer technology and processing has been rewritten and expanded. The section listing Web sites has been updated. The nomenclature section has been enlarged, and a new appendix on the stereoge- ometry of polymers has been added. Additional aids and appendixes are included: how to study, nomenclature, over 1500 trade names, about 400 citations to appropriate Journal of Chemical Education and Poly- mer News articles, Web sites dealing with polymer topics, and over 100 structures of common polymers.
Charles E. Carraher, Jr.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Acknowledgments
I gratefully acknowledge the contributions of Herman Mark of the Polytechnic Institute of New York; Charles L. McCormick, University of Southern Mississippi; William Feld, Wright State University; Eli Pearce, Polytechnic Institute of New York; Fredinard Rodri- guez, Cornell University; and Otto Vogl, University of Massachusetts, for their reviewing, advising, and counseling efforts; and Charles Carraher III and Shawn Carraher for their help in proofing and indexing. I also thank the following for their special contributions to the book: Charles Gebel- ein, Les Sperling, Anglo Volpe, Stam Israel, Carl Wooten, Rita Blumstein, Eckhard Hell- muth, Frank Millich, Norman Miller, Rudy Deanin, Guy Donaruma, Leo Mandelkem, R. V. Subramanian, Charles Pittman, Brian Currell, C. Bamford, Roger Epton, Paul Flory, Charles Overberger, William Bailey, Jim O’Donnell, Rob Burford, Edgar Hardy, John H. Coates, Don Napper, Frank Harris, G. Allan Stahl, John Westerman, William A. Field, Nan-Loh Yang, Sheldon Clare, E. N. Ipiotis, D. H. Richards, G. Kirshenbaum, A. M. Sarquis, Lon Mathias, Sukumar Maiti, S. Temin, Yoshinobu Naoshima, Eberhard Neuse, John Sheats, George Hess, David Emerson, Kenneth Bixgorin, Thomas Miranda, M. B. Hocking, Marsha Colbert, Joseph Lagowski, Dorothy Sterling, Amanda Murphy, John Kloss, Qingmao Zhang, Bhoomin Pandya, Ernest Randolph, Alberto Rivalta, and Fengchen He. This book could not have been written without the long-time efforts of Professor Herman Mark, who was one of the fathers of polymer science. For the fourth edition, a special thanks for the assistance of Colleen Carraher. I acknowledge the kind permission of Gerry Kirshenbaum and Polymer News for allowing us to use portions of articles that have appeared in Polymer News. Finally, I thank Edward S. Wilks for his help with the section on “Chemical Ab- stracts–Based Polymer Nomenclature.”
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Polymer Nomenclature
As with most areas of science, names associated with reactions, particular chemical and physical tests, etc., were historically derived with few overall guiding principles. Further, the wide diversity of polymer science permitted a wide diversity in naming polymers. Even though the International Union of Pure and Applied Chemistry (IUPAC) has a long-standing commission associated with the nomenclature of polymers [reports include “Report on nomenclature in the field of macromolecules,” Journal of Polymer Science, 8, 257 (1952); “Report on nomenclature dealing with steric regularity in high polymers,” Pure and Applied Chemistry, 12, 645 (1966); “Basic definitions of terms relating to poly- mers,” IUPAC Information Bull. App., 13, 1 (1971); and “Nomenclature of regular single- strand organic polymers,” Macromolecules, 6(2), 149 (1973)], most of these suggestions for naming of simple polymers have not yet been accepted by many in the polymer science community. Although there is wide diversity in the practice of naming polymers, we will concen- trate on the most utilized systems.
COMMON NAMES Little rhyme or reason is associated with the common names of polymers. Some names are derived from the place of origin of the material, such as Hevea brasiliensis—literally “rubber from Brazil”—for natural rubber. Other polymers are named after their discoverer, as is Bakelite, the three-dimensional polymer produced by condensation of phenol and formaldehyde, which was commercialized by Leo Baekeland in 1905.
Portions adapted from C. Carraher, G. Hess, and L. Sperling, J. Chem. Ed., 64(1), 36 (1987) and L. H. Sperling W. V. Metanomski, and C. Carraher, Appl Polym Science (C. Craver and C. Carraher, eds.), Elsevier, New York, 2000.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. For some important groups of polymers, special names and systems of nomenclature were invented. For example, the nylons were named according to the number of carbons in the diamine and carboxylic acid reactants (monomers) used in their syntheses. The nylon produced by the condensation of 1,6-hexanediamine (6 carbons) and sebacic acid (10 carbons) is called nylon-6,10.
Similarly, the polymer from 1,6-hexanediamine and adipic acid (each with 6 carbons) is called nylon-6,6 or nylon-66, and the nylon from the single reactant caprolactam (6 carbons) is called nylon-6.
SOURCE-BASED NAMES Most polymer names used by polymer scientists are source-based; i.e., they are based on the common name of the reactant monomer, preceded by the prefix “poly.” For example, polystyrene is the most frequently used name for the polymer derived from the monomer 1-phenylethene, which has the common name styrene.
The vast majority of polymers based on the vinyl group (CH2BCHX) or the vinyli- dene group (CH2BCX2) as the repeat unit are known by their source-based names. For example, polyethylene is derived from the monomer ethylene, poly(vinyl chloride) from the monomer vinyl chloride, and poly(methyl methacrylate) from methyl methacrylate:
Many condensation polymers are also named in this manner. In the case of poly(eth- ylene terephthalate), the glycol portion of the name of the monomer, ethylene glycol, is used in constructing the polymer name, so that the name is actually a hybrid of a source- based and a structure-based name.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. This polymer is well known by trade names, such as Dacron, or its common grouping, polyester. Although it is often suggested that parentheses be used in naming polymers of more than one word [like poly(vinylidene chloride)] but not for single-word polymers (like polyethylene), many authors omit entirely the use of parentheses for either case (like polyvinylidene chloride). Thus there exists a variety of practices with respect to even source-based names. Copolymers are composed of two or more monomer units. Source-based names are conveniently used to describe copolymers by using an appropriate term between the names of the monomers. Any of a half dozen or so connecting terms may be used, depending on what is known about the structure of the copolymer. When no information is specified about the sequence of monomer units in the copolymer, the connective term co is used in the general format poly(A-co-B), where A and B are the names of the two monomers. An unspecified copolymer of styrene and methyl methacrylate would be called poly[sty- rene-co-(methyl methacrylate)]. Kraton, the yellow rubber-like material on the bottom of many running shoes, is an example of a copolymer about which structural information is available. It is formed from a group of styrene units, i.e., a “block” of polystyrene, attached to a group of butadiene units, or a block of polybutadiene, which is attached to another block of polystyrene forming a triblock copolymer. The general representation of such a block copolymer is —AAAAABBBBBAAAAA—, where each A or B represents an individual monomer unit. The proper source-based name for Kraton is polystyrene-block-polybutadiene-block- polystyrene, with the prefix “poly” being retained for each block.
STRUCTURE-BASED NAMES Although source-based names are generally employed for simple polymers, the interna- tional body responsible for systematic nomenclature of chemicals, IUPAC, has published a number of reports for the naming of polymers, now being accepted for more complex polymers. The IUPAC system names the components of the repeat unit, arranged in a prescribed order. The rules for selecting the order of the components to be used as the repeat unit are found elsewhere [Macromolecules, 6(2), 149 (1973); Pure and Applied Chemistry, 48, 373 (1976), 57, 149 (1985), and 57, 1427 (1985)]. However, once the order is selected, the naming is straightforward for simple linear molecules, as indicated in the following examples:
A listing of source- and structure-based names for some common polymers is given in Table 1.
LINKAGE-BASED NAMES Many polymer “families” are referred to by the name of the particular linkage that connects the polymers (Table 2). The family name is “poly” followed by the linkage name. Thus,
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 1 Source- and Structure-Based Names
Table 2 Linkage-Based Names
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. those polymers that contain the carbonate linkage are known as polycarbonates; those containing the ether linkage are called polyethers, etc.
CHEMICAL ABSTRACTS – BASED POLYMER NOMENCLATURE The most complete indexing of any scientific discipline is done in chemistry and is pro- vided by Chemical Abstracts (CA). Almost all of the modern searching tools for chemicals and chemical information depend on CA for at least some of their information base. It is critical for polymer chemists to have some grasp of how CA names chemical compounds. The full description of the guidelines governing the naming of chemical compounds and related properties is given in Appendix IV at the end of the CA Index Guide. This descrip- tion is about 200 pages. While small changes are made with each new edition, the main part has remained largely unchanged since 1972. CA organizes the naming of materials into twelve major arrangements that tie to- gether about 200 subtopics. These main topic headings are A. Nomenclature systems and general principles B. Molecular skeletons C. Principal chemical groups D. Compound classes E. Stereochemistry and stereoparents F. Specialized substances G. Chemical substance names for retrospective searches H. Illustrative list of substituent prefixes J. Selective bibliography of nomenclature of chemical substances K. Chemical prefixes L. Chemical structural diagrams from CA Index Names M. Index
The section dealing with polymers is subtopic 222: Polymers. The subsection on polymers builds on the foundations given before. Some of the guidelines appear to be confusing and counterproductive to the naming of polymers, but the rules were developed for the naming of small molecules. Following is a description of the guidelines that are most important to polymer chemists. Additional descriptions are found in the CA Appendix IV itself and in articles listed in the readings. Appendix IV concentrates on linear polymers. A discussion of other more complex polymeric materials is also found in articles cited in the readings section.
General Rules In the chemical literature—in particular, systems based on Chemical Abstracts—searches for particular polymers can be conducted using the Chemical Abstracts Service number, (CAS ) (where known) or the repeat unit. The International Union of Pure and Applied Chemistry (IUPAC) and CAS have agreed on a set of guidelines for the identification, orientation, and naming of polymers based on the structural repeat unit (SRU). IUPAC refers to polymers as “poly(constitutional repeat unit)” while CAS utilizes a “poly(struct- ural repeating unit).” These two approaches typically give similar results. Here we will practice using the sequence “identification, orientation, and naming,” first by giving some general principles and finally by using specific examples.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. In the identification step, the structure is drawn, usually employing at least two repeat units. Next, in the orientation step, the guidelines are applied. Here we concentrate on basic guidelines. Within these guidelines are subsets of guidelines that are beyond our scope. Structures will generally be drawn in the order, from left to right, in which they are to be named.
Seniority The starting point for the naming of a polymer unit involves determining seniority among the subunits. A. This order is Heterocyclic ringsϾ Greatest number of most preferred acyclic heteroatomsϾ Carbocyclic ringsϾ Greatest number of multiple bondsϾ Shortest path or route (or lowest locant) to these substituents Chains containing only carbon atoms. with the symbol “Ͼ” indicating “is senior to.” This is illustrated below. Heterocyclic ring Ͼ Acyclic hetero atoms Ͼ Carbocyclic rings
Ͼ MOMCH2M Ͼ
Ͼ Multiple bonds Ͼ Lowest locant Ͼ Only carbon chains
Ͼ MCHBCHM Ͼ MCF2MCHF Ͼ MCHFMCF2M Ͼ MCH2MCH2M This order is partially derived from guidelines found in other sections such as Section 133, Compound Radicals, where the ordering is given as Greatest number of acyclic hetero atomsϾ Greatest number of skeletal atomsϾ Greatest number of most preferred acyclic hetero atomsϾ Greatest number of multiple bondsϾ Lowest locants or shortest distance to nonsaturated carbons. The lowest locant or shortest distance refers to the number of atoms from one senior subunit to the next most senior subunit when there is only one occurrence of the senior subunit. This order refers to the backbone and not substitutions. Thus, polystyrene and poly(- vinyl chloride) are contained within the “chains containing only carbon atoms” grouping. B. For ring systems the overall seniority is HeterocyclicϾ Carbocyclic but within the rings there is also an ordering (Section 138) that is
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Nitrogenous heterocyclicϾ HeterocyclicϾ Largest number of ringsϾ Cyclic system occurring earliest in the following list of systems spiro, bridged fused, bridges nonfused, fusedϾ Largest individual ring (applies to fused carbocyclic systems)Ͼ Greatest number of ring atoms
For example,
and
and
C. For hetero-atomed linear chains or cyclic rings, the order of seniority is O Ͼ S Ͼ Se Ͼ Te Ͼ N Ͼ P Ͼ As Ͼ Sb Ͼ Bi Ͼ Si Ͼ Ge Ͼ Sn Ͼ Pb Ͼ B Ͼ Hg. Thus, because MOM CH2—is senior to MSMCH2M, it would be named first in a polymer that contained both MOMCH2M and MSMCH2 Msegments. Further, a polymer containing these alternating units would not be poly(thiomethyleneoxymethylene) but would be named poly(oxymethylenethiomethylene). Another example,
O
M(MOMCMCH2M)nM is named poly[oxy(1-oxy-1,2-ethanediyl)] or less preferred poly[oxy(1-oxoethylene)] but not poly[(2-oxo-1,2-ethanediyl)oxy] or poly[(2-oxoethylene)oxy]. D. In rings, unsaturation is senior to saturation. The more unsaturated, the more senior with all other items being equal. Thus 1,4-phenylene is senior to 2,5-cyclohexadiene-1,4- diyl, which in turn is senior to 2-cyclohexene-1,4-diyl, which is senior to 1,4-cyclohexaned-
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. iyl. For linear chains MCHBCHMCHBCHM is senior to MCHBCHMCH2MCH2M, which is in turn senior to the totally saturated chain segment.
Route A. From the senior subunit determined from “Seniority” take the shortest path (smallest number of atoms) to another like or identical unit or to the next most preferred subunit. Thus for the homopolymer poly(oxymethylene) it is simply going from one oxygen to the next oxygen and recognizing that this is the repeat unit. For a more complex ether this means going until the chain begins to repeat itself going in the shortest direction from the senior unit or atom to the next most senior unit or atom. Thus, MOMCMC- MOMCMCMCM is named “oxy-1,2-ethanediyloxy-1,3-propanediyl” rather than “oxy- 1,3-propanediyloxy-1,2-ethanediyl. B. Where path lengths are equal, such as in some nylons, the repeat unit is named so that the heteroatom “N” is first named and then the more highly substituted (carbonyl) unit appears next. Thus, nylon 3,3, with the structure OO
M(MNHMCMCH2MCMNHMCH2MCH2MCH2M)nM is named poly[imino(1,3-dioxo-1,3-propanediyl)imino-1,3-propanediyl]. C. In otherwise identical subunits, there are three items to be considered in decreasing order of importance: 1. Maximum substitution: thus, 2,3,5-trichloro-p-phenylene is senior to 2,5-dichl- oro-p-phenylene which in turn is senior to 2-chloro-p-phenylene, 2. Lowest locants: thus, 2,3-dichloro-p-phenylene is senior to 2,5-dichloro-p-phe- nylene, 3. Earliest alphabetical order: thus, 2-bromo-p-phenylene is senior to 2-chloro-p- phenylene that is senior to 2-iodo-p-phenylene. D. Where there is no conflict with other guidelines, multiple bonds should be assigned the lowest locants; in rings, double bonds are senior to single bonds; in acyclic carbon chains, double bonds are senior to triple bonds, which are in turn senior to single bonds. Thus, the polymer from 1,3-butanediene polymerized in the so-called “1,4M” mode is usually drawn as M(MCMCBCMCM)M but it is named as drawn as M(MCBCMCMCM)M and named poly(1-butene-1,4-diyl) with the appropriate “cis-” or “trans-” designation. Polyisoprene, typically drawn as
M(MCH2MC(CH3)BCHMCH2M)nM is frequently named poly(2-methyl-1,3-butadiene) but it is named as though its structure is
M(C(CH3)BCHMCH2MCH2M)nM with the name poly(1-methyl-1-butene-1,4-diyl). Substituents are named as one of several classes. The most important ones are dealt with here. For monoatomic radicals from borane, methane, silane (and other Group IVA ele- ments) they are named by replacing the “ane” ending with “yl,” “ylene,” and “ylidyne” to denote the loss of one, two, or three hydrogen atoms, respectively.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. H2BM boryl H3CM methyl H2CB methylene HCϵ methylidyne Acyclic hydrocarbon radicals are named from the skeletons by replacing “ane,” “ene,” and “yne” suffixes by “yl,” “enyl,” and “ynyl,” respectively.
CH3MCH2M ethyl CH3MCH2MCH2M propyl MCH2MCH2M 1,2-ethanediyl MCHBCHM 1,2-ethenediyl H2CBCHMCHB2-propenylidene
MCH2MCMCH2M 1,3-propanediyl-2-ylidene |
MCH2MCHMCH2M 1,2,3-propanetriyl Table 3 contains the names of selected bivalent radicals that may be of use to polymer chemists.
Searching Polymers from a single monomer are indexed at the monomer name with the term “homo- polymer” cited in the modification. Thus, polymers of 1-pentene are listed under the monomer 1-Pentene homopolymer Polymers formed from two or more monomers such as condensation polymers and copoly- mers, and homopolymers are indexed at each inverted monomer name with the modifying term “polymer with” followed by the other monomer names in uninverted alphabetical order. The preferential listing for identical heading parents is in the order: (a) maximum number of substituents, (b) lowest locants for substituents, (c) maximum number of occur- rences of index heading parent, and (d) earliest index position of the index heading. Examples are 1-Petene polymer with 1-hexene 2,5-Furandione polymer with 1,4-butanedisulfonic acid Silane, dichlorodiethyl- polymer with dichlorodiphenylsilane Although the percentage composition of copolymers (i.e., the ratio of comonomers) is not given, copolymers with architecture other than random or statistical are identified as “alternating, block, graft, etc.” Random or statistical copolymer are not so identified in the CA index. Oligomers with definite structure are noted as dimer, trimer, tetramer,... Often, similar information is found at several sites. For instance, for copolymers of 1-butene and 1-hexene, information will be listed under both 1-butene and 1-hexene, but because the listings are not necessarily complementary both entries should be consulted for completeness. CA’s policy for naming acetylenic, acrylic, methacrylic, ethylenic, and vinyl poly- mers is to use the source-based method, and source-based representation is used to depict the polymers graphically; thus, a synonym for polyethene is polyethylene and not poly(1,2-
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 3 Names of Selected Bivalent Radicals
“Common” or “trivial” name CAS name Structure
Adipyl, adipoyl 1,6-Dioxo-1,6-hexanediyl MCOM(CH2)4MCOM 1,4-Butanediyl 1,4-Butanediyl M(CH2)4M Carbonyl Carbonyl MCOM Diglycoloyl Oxybis (1-oxo-2,1-ethanediyl) MCOMCH2MOMCH2-COM Ethylene 1,2-Ethanediyl MCH2MCH2M Imino Imino MNHM Iminodisulfonyl Iminobis(sulfonyl) MSO2MNHMSO2M Methene, methylene Methylene MCH2M Oxybis(methylenecar- Oxybis[(1-oxo-2, MNHCOMCH2MOMCH2M bonylimino) 1-ethanediyl)imino)] COMNHM Pentamethylene 1,5-Pentanediyl M(CH2)5M p-Phenylene 1,4-Phenylene
Phenylenedimethylene 1,4-Phenylenebis(methylene)
Phenylenedioxy 1,4-Phenylenebis(oxy)
Sebacoyl 1,10-Dioxo-1,10-decanediyl MCOM(CH2)8COM
Styrenyl 1-Phenyl-1,2-ethanediyl
Sulfonyl, sulfuryl Sulfonyl MSO2M Tartaroyl 2,3-Dihydroxy-1,4-dioxo-1, MCOMCH(OH)MCH(OH)MCOM 4-butanediyl
Terephthaloyl 1,4-Phenylenedicarbonyl
Thio Thio MSM Thionyl Sulfinyl MSOM Ureylene Carbonyldiimino MNHMCOMNHM Vinylene 1,2-Ethenediyl MCHFCHM In this text we typically employ the more “common” (semisystematic or trivial) names of polymers, but it is im- portant in searching the literature using any CA-driven search engine that you be familiar with CA naming for both monomers and polymers.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. ethanediyl); a synonym for poly-1-propylene is polypropylene, and poly(vinyl alcohol) is named ethenol, homopolymer although ethenol does not exist. Thus, these polymers are named and represented structurally by the source-based method, not the structure-based method.
Examples Following are examples that illustrate CAS guidelines for naming.
M(CH2M)nM Poly(methylene) (to locate poly(methylene) in the Registry file by name, search for “Ethane, homopolymer”)
M(CH2MCH2M)nM Poly(ethylene) (to search for poly(ethylene) search for “Ethane, homopolymer”)
M(CHBCHM)nM Poly(1,2-ethenediyl) OO
M(CMCMCH2MCH2M)nM Poly1,2-dioxo-1,4-butanediyl
M(MCHBCHMCH3MCH2M)nM Poly(3-methyl-1-butene-1,4-diyl |
CH3 O
M(NHMCMCH2MCH2M)nM Poly[imino(1-oxo-1,3-propanediyl)] O
M(MOMCMOMCH2CH2M)nM Poly[oxocarbonyloxy(1,2-ethanediyl)]
M(MOMCH2MSMCH2MNHMCH2MCH2 Poly(oxymethylenethiomethyleneimino-1,2- MSMNH CH2MCH2M)nM ethanediylthioimino-1,2-ethanediyl)
M(MCFHMCH2M)nM Poly(1-fluoro-1,2ethanediyl) search for under “Ethene, fluoro-homopolymer”)
M(MOMCH2MCH2M)nM Poly(oxy-1,2-ethanediyl)
M(MOMCH2M)nM Poly(oxymethylene)
Poly(3,5-pyridinediyl-2,5-thiophenediyl)
OO Poly[imino(1,6-dioxo-1,6hexanediyl)imino-
M[MNHMCM(CH2)4MCMNHM(CH2)6M]nM 1,6-hexanediyl]
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Poly(oxy-1,4-phenylene)
Poly(thio-1,4-phenylene)
Poly(oxy1,2-ethanediyloxycarbonyl-1,4- phenylenecarbonyl)
Poly(imino-1,4-phenyleneiminocarbonyl- 1,4-phenylenecarbonyl)
TRADE NAMES, BRAND NAMES, AND ABBREVIATIONS Trade (and/or brand) names and abbreviations are often used to describe materials. They may be used to identify the product of a manufacturer, processor or fabricator and may be associated with a particular product or with a material or modified material. Trade names are used to describe specific groups of materials that are produced by a specific company or under licence of that company. Bakelite is the trade name given for the phenol- formaldehyde condensation polymer developed by Baekeland. A sweater whose contents are described as containing Orlon contains polyacrylonitrile fibers that are “protected” under the Orlon trademark and produced or licenced to be produced by the holder of the Orlon trademark. Also, Carina, Cobex, Dacovin, Darvic, Elvic, Geon, Koroseal, Marvinol, Mipolam, Opalon, Plioflex, Rucon, Solvic, Trulon, Velon, Vinoflex, Vygen, and Vyram are all trade names for poly(vinyl chlorides) manufactured by different companies. Some polymers are better known by their trade name than their generic name. For instance, polytetrafluoroethylene is better known as Teflon, the trade name held by DuPont. An extensive listing of trade names is given in Appendix B of this text. Abbreviations, generally initials in capital letters, are also employed to describe materials. Table 4 contains a listing of some of the more widely employed abbreviations and the polymer associated with the abbreviation.
COPOLYMERS Generally, copolymers are defined as polymeric materials containing two or more kinds of mers. It is important to distinguish between two kinds of copolymers—those with statistical distributions of mers or at most short sequences of mers (Table 5), and those containing long sequences of mers connected in some fashion (Table 6).
ACKNOWLEDGMENTS The author thanks William Work, Les Sperling, and W. V. (Val) Metanomski for their assistance with polymer nomenclature. The author also acknowledges the assistance of Edward S. Wilks for his help in preparing the section on ‘‘Chemical Abstracts Based Polymer Nomenclature.’’
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 4 Abbreviations for Selected Polymeric Materials
Table 5 Short Sequence Copolymer Nomenclature
Table 6 Long Sequence Copolymer Nomenclature
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. SUMMARY While there are several important approaches to the naming of polymers, in this book we utilize common and source-based names because these are the names that are most com- monly utilized by polymer chemists and the general public and these names, in particular the source-based names, allow a better understanding of the basics of polymers as a function of polymer—structure relationships based on starting materials. Even so, those wishing to do further work in polymers must become proficient in the use of the guidelines used by Chemical Abstracts and IUPAC.
SELECTED READINGS
Compendium of Macromolecular Nomenclature, CRC Press, Boca Raton, Florida, 1991. Polymer nomenclature, Polymer Preprints, 33(1), 6–11 (1992). Basic classification and definitions of polymerization reactions, Pure Appl. Chem., 66:2483–2486 (1994). Graphic representations (chemical formulae) of macromolecules, Pure Appl. Chem., 66:2469–2482 (1994). Structure-based nomenclature for irregular single-strand organic polymers, Pure Appl. Chem., 66: 873–889 (1994). Nomenclature of regular double-strand (ladder and spiro) organic polymers, Pure Appl. Chem., 65: 1561–1580 (1993). A. D. Jenkins and K. L. Loening, Nomenclature, in Comprehensive Polymer Science (G. Allen, J. Bevington, C. Booth, and C. Price, eds.), Vol. 1, Pergamon Press, Oxford, 1989, pp. 13–54. N. M. Bikales, Nomenclature, in Encyclopedia of Polymer Science and Engineering, 2nd ed. (H. F. Mark, N. M. Bikales, C. G. Overberger, and G. Menges, eds.), Vol. 10, Wiley, New York, 1987, pp. 191–204. Definitions of terms relating to crystalline polymers, Pure Appl. Chem., 61:769–785 (1989). A classification of linear single-strand polymers, Pure Appl. Chem., 61:243–254 (1989). Definitions of terms relating to individual macromolecules, their assemblies, and dilute polymer solutions, Pure Appl. Chem., 61:211–241 (1989). Use of abbreviations for names of polymeric substances, Pure Appl. Chem., 59:691–693 (1987). Source-based nomenclature for copolymers, Pure Appl. Chem., 57:1427–1440 (1985). Nomenclature for regular single-strand and quasi single-strand inorganic and coordination polymers, Pure Appl. Chem., 57:149–168 (1985). Notes on terminology for molar masses in polymer science: makromol. chem., 185, Appendix to No. 1 (1984). J. Polym. Sci., Polym. Lett. Ed., 22, 57 (1984). J. Macromol. Sci. Chem., A21, 903 (1984). J. Colloid Interface Science, 101, 227 (1984). Br. Polym. J., 17, 92 (1985). Stereochemical definitions and notations relating to polymers, Pure Appl. Chem., 53:733–752 (1981). Nomenclature of regular single-strand organic polymers, Pure Appl. Chem., 48:373–385 (1976). Basic definitions of terms relating to polymers, Pure Appl. Chem., 40:479–491 (1974).
ADDITIONAL READING
Carraher, C.(2001) J. Polym. Materials, 17(4):9–14. Carraher, C., Hess, G., Sperling, L. (1987) J. Chem. Ed., 64:36–38. Chemical Abstract Service, Appendix IV; Chemical Abstracts Service, 2540 Olentangy River Rd., PO Box 3012, Columbus, OH 43210. IUPAC (1952) Report on Nomenclature in the Field of Macromolecules, J. Poly. Sci., 8:257–277.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. IUPAC (1966) Report on Nomenclature Dealing with Steric Regularity in High Polymers, Pure Appl Chem, 12:645–656; previously published as M. L. Huggins, G. Natta, V. Desreus, and H. Mark (1962) J. Poly Sci., 56:153–161. IUPAC (1969) Recommendations for Abbreviations of Terms Relating to Plastics and Elastomers. Pure Appl. Chem., 18:583–589. IUPAC (1991) Compendium of Macromolecular Nomenclature, Blackwell Scientific Pubs., Oxford, UK, 171 pp. (Collection of summaries) IUPAC (1976) Nomenclature of Regular Single-Strand Organic Polymers. Pure Appl. Chem., 48: 373–385. IUPAC (1981) Stereochemical Definitions and Notations Relating to Polymers. Pure Appl. Chem., 53:733–752. IUPAC (1985) Source-Based Nomenclature for Copolymers. Pure Appl. Chem., 57:1427–1440. IUPAC (1987) Use of Abbreviations for Names of Polymeric Substances. Pure Appl. Chem., 59: 691–693. IUPAC (1989) A Classification of Linear Single-Strand Polymers. Pure Appl. Chem., 61:243–254. IUPAC (1989) Definitions of Terms Relating to Individual Macromolecules, Their Assemblies, and Dilute Polymer Solutions. (1989) Pure Applied Chemistry 61:211–241. IUPAC (1989) Definition of Terms Relating to Crystalline Polymers. Pure Appl. Chem., 61:769–785. IUPAC (1993) Nomenclature of Regular Double-Strand (Ladder or Spiro) Organic Polymers. Pure Appl. Chem., 65:1561–1580. IUPAC (1994) Graphic Representations (Chemical Formulae) of Macromolecules. Pure Appl. Chem., 66:2469–2482. IUPAC (1994) Structure-Based Nomenclature for Irregular Single-Strand Organic Polymers. Pure Appl. Chem., 66:873–889. IUPAC (1985) Nomenclature for Regular Single-Strand and Quasi-Single Strand Inorganic and Coordination Polymers. Pure Appl. Chem., 57:149–168. Polymer Preprints 32(1) (1991) 655; 33(2) (1992) 6; 34(1) (1993) 6; 34(2) (1993) 6; 35(1) (194) 6; 36(1) (1995) 6; 36(2) (1995) 6; 37(1) (1996) 6; 39(1) (1998)9; 39(2) (1998) 6; 40(1) (1999) 6; 41(1) (2000) 6a. Polymeric Materials: Science and Engineering, 68 (1993) 341; 69 (1993) 575; 72 (1995) 612; 74 (1996) 445; 78 (1998), Back Page; 79 (1998) Back Page; 80 (1999), Back Page; 81 (1999) 569.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Contents
Foreword Otto Vogl Preface Acknowledgments Polymer Nomenclature Studying Polymer Chemistry 1/ INTRODUCTION TO POLYMER SCIENCE 1.1 History of Polymers 1.2 Today’s Marketplace Summary Glossary Exercises Bibliography 2/ POLYMER STRUCTURE (MORPHOLOGY) 2.1 Stereochemistry of Polymers 2.2 Molecular Interactions 2.3 Polymer Crystals 2.4 Amorphous Bulk State 2.5 Polymer Structure–Property Relationships 2.6 Crystalline and Amorphous Combinations Summary Glossary Exercises Bibliography 3/ MOLECULAR WEIGHT OF POLYMERS 3.1 Introduction
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. 3.2 Solubility 3.3 Average Molecular Weight Values 3.4 Fractionation of Polydisperse Systems 3.5 Chromatography 3.6 Osmometry 3.7 End-Group Analysis 3.8 Ebulliometry and Cryometry 3.9 Refractometry 3.10 Light Scattering Measurements 3.11 Ultracentrifugation 3.12 Small-Angle X-Ray Scattering 3.13 Mass Spectrometry 3.14 Viscometry Summary Glossary Exercises Bibliography 4/ TESTING AND SPECTROMETRIC CHARACTERIZATION OF POLYMERS 4.1 Electric Properties: Theory 4.2 Electric Measurements 4.3 Weatherability 4.4 Optical Property Tests 4.5 Chemical Resistance 4.6 Spectronic Characterization of Polymers 4.7 Thermal Analysis 4.8 Thermal Property Tests 4.9 Flammability 4.10 Surface Characterization 4.11 Amorphous Region Determinations 4.12 Particle Size 4.13 Measurement of Adhesion Summary Glossary Exercises Bibliography 5/ RHEOLOGY AND PHYSICAL TESTS 5.1 Rheology 5.2 Typical Stress–Strain Behavior 5.3 Stress–Strain Relationships 5.4 Specific Physical Tests Summary Glossary Exercises Bibliography 6/ STEP-REACTION POLYMERIZATION OR POLYCONDENSATION REACTIONS 6.1 Comparison Between Polymer Type and Kinetics of Polymerization
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. 6.2 Introduction 6.3 Stepwise Kinetics 6.4 General Step-Reaction Polymerization 6.5 Polycondensation Mechanisms 6.6 Polyesters and Polycarbonates 6.7 Synthetic Polyamides 6.8 Polyimides 6.9 Polybenzimidazoles and Related Polymers 6.10 Polyurethanes and Polyureas 6.11 Polysulfides 6.12 Polyethers 6.13 Polysulfones 6.14 Poly(ether ether ketone) and Polyketones 6.15 Phenolic and Amino Plastics 6.16 Synthetic Routes Summary Glossary Exercises Bibliography
7/ IONIC CHAIN-REACTION AND COMPLEX COORDINATIVE POLYMERIZATION (ADDITION POLYMERIZATION) 7.1 Cationic Polymerization 7.2 Anionic Polymerization 7.3 Stereoregularity 7.4 Polymerization with Complex Coordination Catalysts 7.5 Soluble Stereoregulating Catalysis 7.6 Polyethylenes 7.7 Polypropylene 7.8 Polymers from 1,4-Dienes 7.9 Polyisobutylene 7.10 Metathesis Reactions 7.11 Zwitterionic Polymerization 7.12 Isomerization Polymerization 7.13 Precipitation Polymerization Summary Glossary Exercises Appendix Bibliography
8/ FREE RADICAL CHAIN POLYMERIZATION (ADDITION POLYMERIZATION) 8.1 Initiators for Free Radical Chain Polymerization 8.2 Mechanism for Free Radical Chain Polymerization 8.3 Chain Transfer 8.4 Polymerization Techniques 8.5 Fluorine-Containing Polymers
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. 8.6 Polystyrene 8.7 Poly(vinyl chloride) 8.8 Solid State Irradiation Polymerization 8.9 Plasma Polymerizations Summary Glossary Exercises Bibliography 9/ COPOLYMERIZATION 9.1 Kinetics of Copolymerization 9.2 The Q-e Scheme 9.3 Commercial Copolymers 9.4 Block Copolymers 9.5 Graft Copolymers 9.6 Elastomers 9.7 Networks—General 9.8 General Information on Block and Graft Copolymers 9.9 Polymer Mixtures—IPNs, Composites, Blends, and Alloys 9.10 Dendrites 9.11 Ionomers Summary Glossary Exercises Bibliography
10/ NATURALLY OCCURRING POLYMERS 10.1 Polysaccharides 10.2 Cellulose 10.3 Cellulose-Regenerating Processes 10.4 Esters and Ethers of Cellulose 10.5 Starch 10.6 Other Polysaccharides 10.7 Proteins 10.8 Nucleic Acids 10.9 Naturally Occurring Polyisoprenes 10.10 Polymer Structure 10.11 Genetic Engineering 10.12 DNA Profiling 10.13 Melanins Summary Glossary Exercises Bibliography 11/ INORGANIC-ORGANIC POLYMERS 11.1 Introduction 11.2 Inorganic Reaction Mechanisms 11.3 Condensation Organometallic Polymers
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. 11.4 Coordination Polymers 11.5 Addition Polymers 11.6 Sol-Gel Summary Glossary Exercises Bibliography 12/ INORGANIC POLYMERS 12.1 Introduction 12.2 Portland Cement 12.3 Other Cements 12.4 Silicates 12.5 Silicon Dioxide (Amorphous) 12.6 Silicon Dioxide (Crystalline Forms)—Quartz Forms 12.7 Silicon Dioxide in Electronic Chips 12.8 Asbestos 12.9 Polymeric Carbon—Diamond 12.10 Polymeric Carbon—Graphite 12.11 Polysulfur 12.12 Ceramics 12.13 High-Temperature Superconductors 12.14 Zeolites Summary Glossary Exercises Bibliography
13/ FILLERS AND REINFORCEMENTS FOR POLYMERS 13.1 Theory of the Effect of Fillers 13.2 Fillers 13.3 Reinforcements 13.4 Coupling Agents 13.5 Composites 13.6 Nanocomposites Summary Glossary Exercises Bibliography 14/ PLASTICIZERS, STABILIZERS, FLAME RETARDANTS, AND OTHER ADDITIVES 14.1 Plasticizers 14.2 Antioxidants 14.3 Heat Stabilizers 14.4 Ultraviolet Stabilizers 14.5 Flame Retardants 14.6 Flame-Retardant Mechanisms 14.7 Colorants
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. 14.8 Curing Agents 14.9 Antistatic Agents (Antistats) 14.10 Chemical Blowing Agents 14.11 Compatibilizers 14.12 Impact Modifiers 14.13 Processing Aids 14.14 Lubricants 14.15 Microorganism Inhibitors Summary Glossary Exercises Bibliography 15/ REACTIONS OF POLYMERS 15.1 Reactions with Polyolefins 15.2 Reactions of Polyenes 15.3 Reactions of Aliphatic Pendant Groups 15.4 Reactions of Aromatic Pendant Groups 15.5 Reactions of Polyamides 15.6 Polymerization Reactions 15.7 General Degradation 15.8 Degradation of Polymers 15.9 Condensation and Chelation Reactions 15.10 Crosslinked Materials 15.11 Internal Cyclization 15.12 Reactivities of End Groups 15.13 Supramolecules and Self-Assembly 15.14 Transfer and Retention of Oxygen 15.15 Nature’s Macromolecular Catalysts 15.16 Mechanisms of Energy Absorption 15.17 Recent Trends Summary Glossary Exercises Bibliography 16/ SYNTHESIS OF REACTANTS AND INTERMEDIATES FOR POLYMERS 16.1 Monomer Synthesis from Basic Feedstocks 16.2 Reactants for Step-Reaction Polymerization 16.3 Synthesis of Vinyl Monomers 16.4 Synthesis of Free Radical Initiators Summary Glossary Exercises Bibliography 17/ POLYMER TECHNOLOGY 17.1 Fibers 17.2 Elastomers 17.3 Films and Sheets
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. 17.4 Polymeric Foams 17.5 Reinforced Plastics (Composites) and Laminates 17.6 Molding 17.7 Casting 17.8 Extrusion 17.9 Coatings 17.10 Adhesives Summary Glossary Exercises Bibliography 18/ SPECIAL TOPICS 18.1 Conductive Polymeric Materials 18.2 Geotextiles 18.3 Solid Waste 18.4 Recycling Codes 18.5 Smart Materials 18.6 Construction and Building 18.7 High-Performance Thermoplastics 18.8 Combinatorial Chemistry 18.9 Synthetic Biomedical Polymers 18.10 The Human Genome and Proteomics 18.11 Proteomics 18.12 Optical Fibers 18.13 Polymerization Reactors 18.14 Material Selection Charts 18.15 Bitumens 18.16 Carbon Nanotubes 18.17 Liquid Crystals 18.18 Emerging Polymers Glossary Bibliography
Solutions
Appendix A: Symbols Appendix B: Trade Names Appendix C: Sources of Laboratory Exercises Appendix D: Syllabus Appendix E: Polymer Core Course Committees Appendix F: Polymer Models Appendix G: Structures of Common Polymers Appendix H: Mathematical Values and Units Appendix I: Comments on Health Appendix J: Comments on ISO 9000 and 14000 Appendix K: Electronic Education—Web Sites Appendix L: Introduction to the Stereogeometry of Polymers Appendix M: Variability of Measurements
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Studying Polymer Chemistry
Studying polymer chemistry is similar to studying any chemistry. Following are some ideas that may assist you as you study polymer chemistry. Much of chemistry is abstract. While much of polymer chemistry is abstract, it is easier to conceptualize—i.e., make mind pictures of what a polymer is and how it should behave—than many other areas of chemistry. For linear polymers, think of a string or rope. Long ropes get entangled with themselves and other ropes. In the same way, polymers entangle with themselves and with other polymer chains that are brought into contact with them. Thus, create mental pictures of the polymers as you study them. Polymers are real and all around us. We can look at polymers on a microscopic or atomic level or on a macroscopic level. The PET bottles we have are composed of long chains of poly(ethylene terephthalate) chains. The aramid tire cord is composed of aromatic polyamide chains. Our hair is made up of complex bundles of fibrous proteins, again polyamides. The chemistry you study is related to the real world in which we live. We experience this “chemistry” at the macroscopic level every day of our lives and this macroscopic behavior is a direct consequence of the atomic level structure and behavior. Make pictures in your mind that allow you to relate the atomic and macroscopic worlds. At the introductory level we often examine only the primary factors that may cause particular polymer behavior. Other factors may become important under particular condi- tions. The polymer chemistry you study at times examines only the primary factors that impact polymer behavior and structure. Nevertheless, it does form the basis for both complex and simple structure–property behavior. The structure–property relationships you will be studying are based on well-known basic chemistry and physical relationships. Because such relationships build on one an- other you need to study in an ongoing manner. Understand as you go along. Read the material BEFORE you go to class. This course is an introductory-level course that builds on firm foundations in all of the core areas of chemistry. Each chapter or topic emphasizes knowledge from one or
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. more of these areas. Polymer chemistry also has its own language. It is a language that requires you to memorize it. Our memory can be short-term or long-term. Short-term memory may be considered as that used by an actor or actress for a TV drama. It really does not need to be totally understood or retained after the final “take.” Long-term memory is required in studying polymer chemistry since it will be called on repeatedly and is used to understand other concepts. In memorizing, learn how you do this best—at what time of day, in what setting, etc. Use as many senses as necessary—be active—read your assignment, write out what you need to learn, say it, listen to yourself say it. Also, look for patterns, create mnemonic devices, avoid cramming too much into too little time, practice associations in all direc- tions, and test yourself. Memorization is hard work. While knowledge involves recalling memorized material, to really know something involves more than simple recall. It involves comprehension, application, evaluation, and integration of the knowledge. Comprehension is the interpretation of this knowledge, i.e., making predictions, applying it to different situations. Analysis involves evaluation of the information and comparison with other information. Synthesis has to do with integration of the information with other information. In studying polymer chemistry, consider doing the following: Skim the text before the lecture. Attend the lecture and take notes. Organize your notes and relate information. Read and study the assigned material. Study your notes and the assigned material. Review and self-test. Learning takes time and effort. Study daily, skimming the text and other study material; think about it, visualize key points and concepts, write down important material, make outlines, take notes, study sample problems, etc. All of this helps, but some approaches may help you more than others, so focus on these modes of learning—but not to the exclusion of the other aspects. In preparing for an exam, consider doing the following: Accomplish the above. Do not wait until the day before the exam to begin studying. Develop good study habits. Study wisely. Study how you study best, i.e., time of day, surroundings, etc. Take care of yourself. Get plenty of sleep the night before the exam. Attend to last-minute details. Is your calculator working? Is it the right kind? Do you have the needed pencils? Review the material once again. Know what kind of test it will be (if possible). Get copies of old exams (if possible). Talk to others who have already taken the course. During the test, Stay cool; do not panic. Read the directions; try to understand what is being asked. In an essay or similar exam work for partial credit, plan your answers ahead of time. In a multiple-choice or true/false exam, eliminate obviously wrong choices. Look over the entire exam. Work on questions that you are sure of, then go to less obvious questions. Check answers if time permits.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Polymer chemistry comprises a variety of chemical content: Facts. The term polymer means “many” (poly) “units” (mers). Concepts. Linear polymers are long molecules like a string. Rules. Solutions containing polymer chains are more viscous, slower flowing, than solutions that do not contain polymers; the relationship between the resistance to flow, viscosity, and molecular weight is given by the Mark-Houwink equation LVN KMa, where LVN is the viscosity number, K and a are constants, and M is molecular weight. Problems. Given an LVN of 0.2 dL/g, a 0.55, and K 6 10 5dL/g, determine the molecular weight of the sample. Although these categories are often integrated within any topic, in this introduction to polymer chemistry the emphasis is often on concepts. However, all aspects are important.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. 1 Introduction to Polymer Science
1.1 HISTORY OF POLYMERS
Since most chemists and chemical engineers are now involved in some phase of polymer science or technology, some have called this the polymer age. Actually, we have always lived in a polymer age. The ancient Greeks classified all matter as animal, vegetable, and mineral. Minerals were emphasized by the alchemists, but medieval artisans emphasized animal and vegeta- ble matter. All are largely polymers and are important to life as we know it. The word polymer is derived from the Greek poly and meros, meaning many and parts, respectively. Some scientists prefer to use the word macromolecule, or large mole- cule, instead of polymer. Others maintain that naturally occurring polymers, or biopoly- mers, and synthetic polymers should be studied in different courses. However, the same principles apply to all polymers. If one discounts the end uses, the differences between all polymers, including plastics, fibers, and elastomers or rubbers, are determined primarily by the intermolecular and intramolecular forces between the molecules and within the individual molecule, respectively, and by the functional groups present. In addition to being the basis of life itself, protein is used as a source of amino acids and energy. The ancients degraded or depolymerized the protein in tough meat by aging and cooking, and they denatured egg albumin by heating or adding vinegar to the eggs. Early humans learned how to process, dye, and weave the natural proteinaceous fibers of wool and silk and the carbohydrate fibers of flax and cotton. Early South American civilizations such as the Aztecs used natural rubber (Hevea brasiliensis) for making elastic articles and for waterproofing fabrics. There has always been an abundance of natural fibers and elastomers but few plastics. Of course, early humans employed a crude plastic art in tanning the protein in animal skins to make leather and in heat-formed tortoise shells. They also used naturally occurring
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. tars as caulking materials and extracted shellac from the excrement of small coccid insects (Coccus lacca). Until Wo¨hler synthesized urea from inorganic compounds in 1828, there had been little progress in organic chemistry since the alchemists emphasized the transmutation of base metals to gold and believed in a vital force theory. Despite this essential breakthrough, little progress was made in understanding organic chemistry until the 1850s, when Kekule´ developed the presently accepted technique for writing structural formulas. However, poly- mer scientists displayed a talent for making empirical discoveries before the science was developed. Charles Goodyear grew up in poverty. He was a Connecticut Yankee born in 1800. He began work in his father’s farm implement business. Later he moved to Philadelphia where he opened a retail hardware store that soon went bankrupt. He then turned to being an inventor. As a child he had noticed the magic material that formed a rubber bottle he had found. He visited the Roxbury India Rubber Company to try and interest them in his efforts to improve the properties of rubber, but they assured him that there was no need to do so. He started his experiments with a malodorous gum from South America in debtor’s prison. In a small cottage on the grounds of the prison, he blended the gum, the raw rubber called hevea rubber, with anything he could find, e.g., ink, soup, caster oil. While rubber- based products were available, they were either sticky or became sticky in the summer heat. He found that treatment of the raw rubber with nitric acid allowed the material to resist heat and not to adhere to itself. This success attracted backers who helped form a rubber company. After some effort he obtained a contract to supply the U.S. Post Office with 150 rubber mailbags. He made the bags and stored them in a hot room while he and his family went away. When they returned they found the bags in a corner of the room, joined together as a mass. The nitric acid treatment was sufficient to prevent surface stickiness, but the internal rubber remained tacky and susceptible to heat. While doing experiments in 1839 at a Massachusetts rubber factory he accidently dropped a lump of rubber mixed with sulfur on the hot stove. The rubber did not melt but rather charred. He had discovered vulcanization, the secret that was to make rubber a commercial success. While he had discovered vulcanization, it would take several years of ongoing experimentation before the process was really commercially useful. During this time he and his family were nearly penniless. Although he patented the process, it was too easily copied and pirated, so that he was not able to profit fully from his invention and years of hard work. Even so, he was able to develop a number of items. Charles Goodyear and his brother Nelson transformed natural rubber, hevea rubber, from a heat-“softenable” thermoplastic to a less heat-sensitive product through the creation of crosslinks between the individual polyisoprene chain-like molecules using sulfur as the crosslinking agent. Thermoplastics are two-dimensional molecules that may be softened by heating. Thermosets are materials that are three-dimensional networks that cannot be reshaped by heating. Rather than melting, thermosets degrade. As the amount of sulfur was increased, the rubber became harder becoming a hard rubber-like (ebonite) material. The spring of 1851 found the construction of a remarkable building on the lawns of London’s Hyde Park. The building was designed by a maker of greenhouses so it was not unexpected that it had a greenhouse look. This Crystal Palace was to house almost 14,000 exhibitors from all over the world. It was the chance for exhibitors to show their wares. Charles Goodyear, then 50 years old, used this opportunity to show off his over two decades worth of rubber-related products. He decorated his Vulcanite Court with
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. rubber walls, roof, furniture, buttons, toys, carpet, combs, etc. Above it hung a six-foot rubber raft and assorted balloons. The European public was introduced to the world of new man-made materials. Within little more than a decade Charles Goodyear was dead. Within a year of his death, the American Civil War broke out. The Union military used about $27 million worth of rubber products by 1865 helping launch the U.S. rubber industry. In 1862 Queen Victoria, while in mourning for her recently departed husband Albert, opened the World’s Fair in London. One of the exhibitors was Alexander Parks. He was displeased with the limited colors available for rubber products (generally dull and dark). In his workshop in Birmingham, England he was working with nitrocellulose, a material made from the treatment of cotton and nitric and sulfuric acids. Nitrocellulose solutions were made from dissolving the nitrocellulose in organic liquids such as ethanol and ether. Thin films and coatings were made by simply pouring the nitrocellulose solutions onto the desired item or surface and allowing the solvent to evaporate. He wanted to make solid objects from nitrocellulose. After years of work he developed a material he called Parkensine from which he made buttons, combs, and many of the items that were made of rubber, except that his materials could be brightly colored, clear, or made to shine like mother-of-pearl. At the London World’s Fair he advertised “Patent Parkesine of various colours: hard elastic, transparent, opaque, and waterproof.” Even with his work he had not developed a material that could be “worked” or was stable, and even with his hype the material never caught on except in exhibition halls. About this time, John Wesley Hyatt, a printer from Albany, New York who was seeking a $10,000 prize for anyone who could come up with a material that was a substitute for ivory billiard balls, developed a material that was stable and could be “worked” from shellac and wood pulp. He then turned to nitrocellulose discovering that shredded nitrocel- lulose could be mixed with camphor and heated under pressure to produce a tough white mass that retained its shape. This material, dubbed celluloid, could be made into the usual rubber-like products, but also solid pieces like boxes, wipe-clean linen, collars, cuffs, and ping-pong balls. Celluloid could also, like the shellac–wood pulp mixture, be cut, drilled, and sawed. But celluloid was flammable and did not stand up well in hot water. The wearers of celluloid dentures truly could have their “teeth curled” when drinking a hot cup of coffee. One of its best qualities was that it could be made to look like other materials—it could be dyed to look like marble, swirled to mimic tortoiseshell and mother- of-pearl, and even look and feel like ivory. It did not make good billiard balls. One account has billiard balls hitting and exploding like a shot that caused cowboys to draw their guns. Both cellulose and cellulose nitrate are linear, or two-dimensional, polymers, but the former cannot be softened because of the presence of multitudinous hydrogen bonds between the chain-like molecules. When used as an explosive the cellulose nitrate is essentially completely nitrated, but the material used by Parks and Hyatt was a dinitrate, still potentially explosive but less so. Parks added caster oil and Hyatt added camphor to plasticize-reduce the effect of the hydrogen bonding—the cellulose nitrate. Worldwide, rubber gained in importance with the invention of the air-filled or pneu- matic tires by a Scotsman, John Dunlop in 1888. He had a successful veterinary practice in Belfast. In his off time he worked to improve the ride of his son’s tricycle. His invention happened at the right time. The automobile was emerging and air-filled tires offered a more gentle ride. Thus was begun the tire industry. All of these inventions utilized natural materials as at least one ingredient. After years of work in his chemistry labs in Yonkers, New York, Leo Baekeland in 1907 announced in
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. an American Chemical Society meeting the synthesis of the first truly synthetic polymeric material, later dubbed Bakelite. Baekeland was born in Belgium in 1863, the son of an illiterate shoe repairman and a maid. He was bright and received his doctorate with highest honors at the age of 20. He could have spent the remaining part of his life in academics in Europe, but heeding the words of Benjamin Franklin, he sailed to America. In the 1890s he developed the first photographic paper, called Velox, that could be developed in synthetic light rather than sunlight. George Eastman saw the importance of this discovery and paid Bakeland $750,000 for the rights to this invention. It was generally recognized by the leading organic chemists of the nineteenth century that phenol would condense with formaldehyde. Since they did not recognize the concept of functionality, Baeyer, Michael, and Kleeberg produced useless crosslinked goos, gunks, and messes and then returned to their research on reactions of monofunctional reactants. However, by the use of a large excess of phenol, Smith, Luft; and Blumer were able to obtain a hard yet meltable thermoplastic material. With his $750,000 Baekeland set up a lab next to his home. He then sought to solve the problem of making the hard material made from phenol and formaldehyde soluble. After many failures, he thought about circumventing the problem by placing the reactants in a mold of the desired shape and allowing them to form the intractable solid material. After much effort he found the conditions under which a hard, clear solid could be made—Bakelite was discovered. Bakelite could be worked, was resistant to acids and organic liquids, stood up well to heat and electrical charge, and could be dyed to give colorful products. It was used to make bowling balls, phonograph records, telephone housings, gears, and cookware. His materials also made excellent billiard balls. Bakelite also acted as a binder for sawdust, textiles, and paper, forming a wide range of composites including Formica laminates, many of which are still used. It was also used as an adhesive giving us plywood. While there is no evidence that Baekeland recognized what polymers were, he ap- peared to have a grasp on functionality and how to “use” functionality to produce thermo- plastic materials that could later be converted to thermosets. Through control of the ratio of phenol to formaldehyde he was able to form a material that was a thermoplastic. He coined the term A-stage resole resin to describe this thermoplastic. This A-stage resole resin was converted to a thermoset crosslink, C-stage Bakelite, by additional heating. Baekeland also prepared thermoplastic resins called novolacs by the condensation of phenol with a lesser amount of formaldehyde under acidic conditions. The thermoplastic novolacs were converted to thermosets by addition of more formaldehyde. While other polymers had been synthesized in the laboratory, Bakelite was the first truly synthetic plastic. The “recipes” used today differ little from the ones developed by Baekeland, showing his ingenuity and knowledge of the chemistry of the condensation of the trifunc- tional phenol and difunctional formaldehyde. While poly(vinyl chloride) was initially formed by Baumann in 1872, it awaited interest until 1926 when B. F. Goodrich discovered how to make sheets and adhesives from poly(vinyl chloride)—and the “vinyl age” began. While polystyrene was probably first formed by Simon in 1839, it was almost 100 years latter, in 1930, that the giant German company I. G. Farben placed polystyrene on the market. Polystyrene molded parts have became common place. Rohm and Haas bought out Plexiglas from a British firm in 1935 and began the production of clear plastic parts and goods, including replace- ments for glass as camera lenses, aircraft windows, clock faces, and car tail lights.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Polymer science was largely empirical, instinctive, and intuitive. Prior to World War I, celluloid, shellac, Galalith (casein), Bakelite, and cellulose acetate plastics; hevea rubber, cotton, wool, silk rayon fibers; Glyptal polyester coatings; bitumen or asphalt; and coumarone-indene and petroleum resins were all commercially available. However, as evidenced by the chronological data shown in Table 1.1, there was little additional develop- ment in polymers prior to World War II because of a general lack of fundamental knowl- edge of polymers. But the theoretical basis was being built. Only a few of the many giants of the industry will be mentioned. Over a century ago, Graham coined the term colloid for aggregates with dimensions in the range of 10 9 to 10 7 m. Unfortunately, the size of many macromolecules is in this range, but it is important to remember that unlike colloids, whose connective forces are ionic and/or secondary forces, polymers are individual molecules whose size cannot be reduced without breaking the covalent bonds that hold the atoms together. In 1860 an oligomer, a small polymer, was prepared from ethylene glycol and its structure correctly given as HM(MOCH2CH2M)nMOH. But when poly(methacrylic acid) was made by Fittig and Engelhorn in 1880 it was incorrectly assigned a cyclic structure. Polymers were thought of as being colloids, or cyclic compounds like cyclohexane. By use of the Raoult and van’t Hoff concepts, several scientists obtained high molecular weight values for these materials and for a number of other polymeric materials. But since the idea of large molecules was not yet accepted they concluded that these techniques were not applicable to these molecules rather than accepting the presence of giant molecules. Hermann Staudinger studied the polymerization of isoprene as early as 1910. In- trigued by the difference between this synthetic material and natural rubber, he began to develop his studies toward such materials. His turn to these questionable materials, of interest to industry but not academically important, was viewed unkindly by his fellow academics. He was told by one of his fellow scientists “Dear Colleague, Leave the concept of large molecules well alone. . . . There can be no such thing as a macromolecule.” But Staudinger systematically synthesized a variety of polymers. In the 1920 paper “Uber Polymerization” he summarized his findings and correctly proposed linear structures for such important polymers as polyoxymethylene and polystyrene. X-ray studies of many natural and synthetic materials were used as structural proof that polymers existed. Fore- most in these efforts were Herman Mark and Linus Pauling. Both of these giants contrib- uted to other important areas of science. Pauling contributed to the fundamental understand- ing of bonding and the importance of vitamins. Mark helped found the academic and communication (journals, short courses, workshops) basis that would allow polymer sci- ence to grow from its very diverse roots. Wallace Hume Carothers is the father of synthetic polymer science. History is often measured by the change in the flow of grains of sand in the hour glass of existence. Carothers is a granite boulder in this hour glass. Carothers was born, raised, and educated in the U.S. midwest. In 1920 he left Tarkio College with his BS degree and entered the University of Illinois where he received his MA in 1921. He then taught at the University of South Dakota where he published his first paper. He returned to receive his PhD under Roger Adams in 1924. In 1926 he became an instructor in organic chemistry at Harvard. In 1927 the DuPont Company decided to begin a program of fundamental research “without any regard or reference to commercial objectives.” This was a radical departure since the bottom line was previously products marketed and not papers published. Charles Stine, director of DuPont’s chemical department, was interested in pursuing fundamental research in the areas of colloid chemistry, catalysis, organic synthesis, and polymer forma-
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 1.1 Chronological Development of Commercial Polymers (to 1971)
Date Material Before 1800 Cotton, flax, wool, and silk fibers; bitumen caulking materials; glass and hydraulic cements; leather and cellulose sheet (paper); natural rubber (Hevea brasiliensis), gutta percha, balata, and shellac 1839 Vulcanization of rubber (Charles Goodyear) 1845 Cellulose esters (Schönbein) 1846 Nitration of cellulose (Schönbein) 1851 Ebonite (hard rubber; Nelson Goodyear) 1860 Molding of shellac and gutta percha 1868 Celluloid (plasticized cellulose nitrate; Hyatt) 1889 Regenerated cellulosic fibers (Chardonnet) 1889 Cellulose nitrate photographic films (Reichenbach) 1890 Cuprammonia rayon fibers (Despeisses) 1892 Viscose rayon fibers (Cross, Bevan, and Beadle) 1897 Poly(phenylene sulfide) 1907 Phenol-formaldehyde resins (Bakelite; Baekeland) 1907 Cellulose acetate solutions (dope; Doerfinger) 1908 Cellulose acetate photographic fibers 1912 Regenerated cellulose sheet (cellophane) 1913 Poly(vinyl acetate) 1914 Simultaneous interpenetrating network (SIN) 1920 Urea-formaldehyde resins 1923 Cellulose nitrate automobile lacquers 1924 Cellulose acetate fibers 1926 Alkyd polyester (Kienle) 1927 Poly(vinyl chloride) (PVC) wall covering 1927 Cellulose acetate sheet and rods 1927 Graft copolymers 1928 Nylon (Carothers, Dupont) 1929 Polysulfide synthetic elastomer (Thiokol; Patrick) 1929 Urea-formaldehyde resins 1931 Poly(methyl methacrylate) (PMMA) plastics 1931 Polychloroprene elastomer (Neoprene, Carothers) 1934 Epoxy resins (Schlack) 1935 Ethylcellulose 1936 Poly(vinyl acetate) 1936 Poly(vinyl butyral) safety glass 1937 Polystyrene 1937 Styrene-butadiene (Buna-S) and styrene-acrylonitrile (Buna-N) copolymer elastomers 1939 Melamine-formaldehyde resins 1939 Nylon 6 (Schlack) 1939 Nitrile rubber (NR) 1940 Isobutylene-isoprene elastomer (butyl rubber; Sparks and Thomas) 1941 Low-density polyethylene (LDPE) 1941 Poly(ethylene terephthalate) (PET) 1942 Butyl rubber 1942 Unsaturated polyesters (Ellis and Rust)
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 1.1 Continued
Date Material
1943 Fluorocarbon resins (Teflon; Plunkett) 1943 Silicones 1943 Polyurethanes (Baeyer) 1945 SBR 1946 Poly(sulfide) rubber (Thiokol) 1948 Copolymers of acrylonitrile, butadiene, and styrene (ABS) 1949 Cyanoacrylate (Goodrich) 1950 Polyester fibers (Whinfield and Dickson) 1950 Polyacrylonitrile fibers 1952 Block copolymers 1953 High impact polystyrene (HIPS) 1953 Polycarbonates (Whinfield and Dickson) 1956 Poly(phenylene ether); Poly(phenylene oxide) (GE) 1956 Polyoxymethylene (acetals) 1957 High-density (linear) polyethylene (HDPE) 1957 Polypropylene 1957 Polycarbonate 1958 Poly(dihydroxymethylcyclohexyl terephthate) (Kodel, Eastman Kodak) 1959 cis-Polybutadiene and cis-polyisoprene elastomers 1960 Ethylene-propylene copolymer elastomers 1961 Aromatic nylons (Aramids, Nomex, Dupont) 1962 Polyimide resins 1964 Poly(phenylene oxide) 1964 Ionomers 1965 Polysulfone 1965 Styrene-butadiene block copolymers 1966 Liquid crystals 1970 Poly(butylene terephthalate) 1974 Polyacetylene 1982 Polyetherimide (GE)
tion and convinced the board to hire the best chemists in each field to lead this research. Stine visited with many in the academic community, including the then president of Har- vard (one of my distant uncles) J. B. Conant, an outstanding chemist himself, who told him about Carothers. Carothers was persuaded to join the DuPont group attracted with a generous research budget and an approximate doubling of his academic salary to $6,000. This was the birth of the Experimental Station at Wilmington, Delaware. Up to this point, it was considered that universities were where discoveries were made and industry was where they were put to some practical use. This separation between basic and applied work was quite prominent at this juncture and continues in many areas even today in some fields of work though the difference has decreased. But in polymers, most of the basic research was done in industry having as its inception the decision of DuPont to bridge this “unnatural” gap between fundamental knowledge and application. In truth, they can be considered as the two hands of an individual and in order to do manual work both hands are important.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Staudinger believed that large molecules were based on the joining, through covalent bonding, of large numbers of atoms. Essentially, he and fellow scientists like Karl Freude- nberg, Herman Mark, Michael Polanyi, and Kurt Myer looked at already existing natural polymers. Carothers however looked at the construction of these giant molecules from small molecules forming synthetic polymers. His intention was to prepare molecules of known structure through the use of known organic chemistry and to “investigate how the properties of these substances depended on constitution.” Early work included the study of polyester formation through reaction of diacids with diols forming polyesters. But he could not achieve molecular weights greater than about 4,000 below the size where many of the interesting so-called polymeric properties appear. DuPont was looking for a synthetic rubber. Carothers assigned Arnold Collins to this task. Collin’s initial task was to produce pure divinylacetylene. While performing the distillation of an acetylene reaction in 1930, he obtained a small amount of an unknown liquid that he set aside in a test tube. After several days the liquid turned to a solid. The solid bounced and eventually was shown to be a synthetic rubber polychloroprene whose properties were similar to those of vulcanized rubber, but it was superior in its resistance to ozone, ordinary oxidation, and to most organic liquids. It was sold under its generic name “neoprene” and the trade name “Duprene.” Also in 1930 Carothers and Julian Hill designed a process to remove water that was formed during the esterification reaction. Essentially, they simply froze the water as it was removed using another recent invention called a molecular still (basically a heating plate coupled to vacuum) allowing the formation longer chains. In April, Hill synthesized a polyester using this approach and touched a glass stirring rod to the hot mass and then pulled the rod away effectively forming strong fibers, the pulling helping reorient the mobile polyester chains. The polyester had a molecular weight of about 12,000. Additional strength was achieved by again pulling the cooled fibers. Further reorienting occurred. This process of drawing or pulling to produce stronger fibers is now known as cold drawing and is widely used in the formation of fibers today. The process of cold drawing was discovered by Carother’s group. While interesting, the fibers were not considered to be of commercial use. Carothers and his group then moved to look at the reaction of diacids with diamines instead of diols. Again, fibers were formed but these initial materials were deemed not to be particularly interesting. In 1934, Paul Flory was hired to work with Carothers to help gain a mathematical understanding of the polymerization process and relationships. Thus, there was an early association between theory and practice or structure–property relationships. The polyamide fiber project began again. One promising candidate was formed from the reaction of adipic acid with hexamethylenediamine, called fiber 66 because each car- bon-containing unit had six carbons. It formed a strong, elastic, largely insoluble fiber with a relatively high melt temperature. DuPont chose this material for production. These polyamides were given the name “nylons.” Thus was born nylon-6,6. It was the first synthetic material whose properties equaled or exceeded the natural analog, namely silk. (In reality, this may not be the truth, but at the time it was believed to be true.) As women’s hemlines rose in the 1930s, silk stockings were in great demand but were very expensive. Nylon changed this. Nylon could be woven into sheer hosiery. The initial presentation of nylon hose to the public was by Stine at a forum of women’s club members in New York City on October 24, 1938. Nearly 800,000 pairs were sold on May 15, 1940 alone—the first day they were on the market. By 1941 nylon hosiery held 30% of the market, but by December 1941 most nylon manufactured was diverted to make parachutes and other items for the war effort.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. From these studies Carothers established several concepts. First, polymers could be formed by employing already known organic reactions but with reactants that had more than one reactive group per molecule. Second, the forces that bring together the individual polymer units are the same as those that hold together the starting materials, namely, primary covalent bonds. Much of the polymer chemistry names and ideas that permeate polymer science were standardized through his efforts. Representing the true multidisciplinary nature of polymers, early important contribu- tions were also made by physicists, engineers, and those from biology, medicine, and mathematics including W. H. Bragg, Peter Debye, Albert Einstein, and R. Simha. World War II helped shape the future of polymers. Wartime demands and shortages encouraged scientists to seek substitutes and materials that even exceeded currently avail- able materials. A polycarbonate (Kevlar) that could stop a speeding bullet was developed as was polytetrafluoroethylene (Teflon), which was superslick. New materials were devel- oped spurred on by the needs of the military, electronics industry, food industry, etc. The creation of new materials continues at an accelerated pace brought on by the need for materials with specific properties and the growing ability to tailor-make giant mole- cules—macromolecules—polymers. The leading polymer scientists of the 1930s agreed that polymers were chain-like molecules and that the viscosities of solution of these macromolecules were dependent on the size and shape of the molecules in the solution. While it is true that the large-scale production of many polymers was accelerated by World War II, it must be recognized that the production of these essential products was dependent on the concepts developed by Staudinger, Carothers, Mark, and other leading polymer scientists. The development of polymer technology since the 1940s has been extremely rapid (Table 1.1). In some instances, such as polymerization in aqueous emulsion systems, the art has preceded the science, but much theory has been developed, so that polymer science today is relevant, based on sound science, and no longer largely empirical.
1.2 TODAY’S MARKETPLACE Polymers are all around us. The soil we grow our foods from is largely polymeric as are the foods we eat. The plants about us are largely polymeric. We are walking exhibits as to the widespread nature of polymers—from our hair and fingernails, our skin, bones, tendons and muscles; our socks, shoes, glasses, undergarments; the morning newspaper; major portions of our automobiles, airplanes, trucks, boats, space craft; our chairs, waste paper baskets, pencils, tables, pictures, coaches, curtains, glass windows; the roads we drive on, the houses we live in, and the buildings we work in; the tapes and CDs we listen to; packaging—all are either totally polymeric or contain a large amount of polymeric materials. Table 1.2 lists some general groupings of important polymers. As shown in Tables 1.3 to 1.6, almost 90 billion pounds (45 million tons) of synthetic polymers is produced annually in the United States, and the growth of the industry is continuing at a faster rate than that of any other industry. There is every reason to believe that this polymer age will continue as long as petroleum and other feedstocks are available and as long as consumers continue to enjoy the comfort, protection, and health benefits provided by elastomers, fibers, plastics, adhesives, and coatings. The 90 billion pounds translates to over 200 pounds of synthetic polymers for every man, woman, and child in the United States. This does not include paper- and wood-related products, natural poly- mers, such as cotton and wool, or inorganic polymers.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 1.2 Polymer Classes: Natural and Synthetic
Inorganic Organic
Natural Synthetic Organic/inorganic Natural Synthetic
Clays Fibrous glass Siloxanes Proteins Polyethylene Cement Poly(sulfur nitride) Polyphosphazenes Nucleic acids Polystyrene Pottery Poly(boron nitride) Polyphosphate Lignins Nylons esters Bricks Silicon carbide Polysilanes Polysaccharides Polyesters Sands Sol-gel networks Melanins Polyurethanes Glasses Polyisoprenes Poly(methyl methacrylate) Rock-like Polytetrafluoroethylen Agate Polyurethane Talc Poly(vinyl chloride) Zirconia Polycarbonate Mica Polypropylene Asbestos Poly(vinyl alcohol) Quartz Ceramics Graphite/diamond Silicas
Table 1.3 U.S. Production of Plastics (Millions of Pounds)
Plastic 1975 1980 1985 1990 1995 2000
Thermosetting resins Epoxies 200 320 390 510 630 660 Polyesters 800 950 1200 1300 1460 2400 Ureas 690 1200 1200 1500 1890 2580 Melamines 120 170 200 220 290 290 Phenolics 1100 1500 2600 2900 3210 3940 Thermoplastics Polyethylene—low densitya 4700 7300 8900 9700 12,900 17,900 Polyethylene—high density 2500 4400 6700 8100 11,200 15,400 Polypropylene 1900 3600 5100 7200 10,900 15,460 Styrene-acrylonitrile 110 100 70 135 130 124 Polystyrene 2700 3500 4100 5000 5600 6600 Acrylonitrile-butadiene-styrene 1200 1700 2000 2300 2900 3100 Polyamides 140 270 400 560 1000 1400 Poly(vinyl chloride) and copolymers 3600 5500 6800 9100 12,300 14,300 Polyester — — 1300 1880 3200 4400 a Includes low density and linear low density. Source: American Plastics Council.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 1.4 U.S. Production of Man-made Fibers (Millions of Pounds)
Fiber 1975 1980 1984 1990 1995 2000
Noncellulosic Acrylics 500 780 670 510 430 340 Nylons 1800 780 2400 2700 2700 2610 Olefins 500 750 1000 1800 2390 3180 Polyesters 3000 4000 3400 3200 3890 3870 Cellulosic Acetate 310 320 200 210 230 — Rayon 440 490 420 300 270 — Glass 550 870 1400 — — —
Source: Fiber Economics Bureau.
Table 1.5 U.S. Production of Paints and Coatings (Millions of Gallons)
Paint/coating 1987 1990 1995 2000
Architectural 530 560 621 668 Product 340 340 376 449 Special 150 200 195 189
Source: Department of Commerce.
Polymers are often divided according to whether they can be melted and reshaped through application of heat and pressure, called thermoplastics, or whether they decompose before they can be melted or reshaped, called thermosets (Table 1.3). While both thermoset polymers and thermoplastics can be recycled, because thermoplastics can be reshaped simply through the application of heat and pressure, recycling of thermoplastics is easier. The number of professional chemists directly involved with polymers is estimated to be between 40% and 60% of all of the chemists employed. The number of chemical industrial employees involved with synthetic polymers is reported by the U.S. Department of Labor to be over one million, or almost 60% of the chemical industrial work force
Table 1.6 U.S. Production of Synthetic Rubber (Millions of Pounds)
Rubber 1975 1980 1985 1990 1995 2000
Styrene-butadiene 2400 2200 1600 1580 1760 1750 Polybutadiene 580 620 660 890 1040 1210 Nitrile 120 120 120 120 160 180 Ethylene-propylene 160 280 400 420 540 700 Other 660 840 920 760 1000 1100
Source: International Institute of Synthetic Rubber Producers.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 1.7 U.S. Chemical Industrial Employment (in Thousands)
Sector 1975 1985 1994 2000
Industrial inorganic 149 143 131 98 Drugs 167 205 264 305 Soaps, cleaners, etc. 142 148 152 158 Industrial organics 150 164 144 121 Agricultural 65 60 56 53 Synthetic polymers 888 1026 1150 1206
Source: U.S. Department of Labor.
(Table 1.7). There are almost another million employed as production workers in the synthetic polymer sector (Table 1.8). Polymeric materials, along with the majority of the chemical industrial products, contribute positively to the balance of trade (Table 1.9). In fact, plastics and resins show the greatest value increase of exports minus imports. Table 1.10 contains a listing of the major chemical producers. All of these producers are involved directly and/or indirectly with polymers.
Table 1.8 U.S. Production Workers (in Thousands), 2000
Sector Number
Inorganic chemicals 55 Drugs 140 Soap, cleaners, etc. 97 Organic chemicals 73 Agricultural 32 Synthetic polymers 909
Source: U.S. Department of Labor.
Table 1.9 U.S. Chemical Trade—Imports and Exports, 1994 and 2000 (Millions of Dollars)
Exports Exports Imports Imports Chemical (1994) (2000) (1994) (2000)
Organic chemicals 12,800 18,900 10,800 28,600 Inorganic chemicals 4100 5500 4100 6100 Oils and perfumes 3500 5000 2000 3200 Dyes, colorants 2300 4200 1900 2700 Medicinals and pharmaceuticals 6100 13,100 4700 14,700 Fertilizers 2700 2500 1300 1700 Plastics and resins 8500 20,100 3300 10,600 Others 7600 12,700 2700 5700 Total chemicalsa 51,600 82,500 33,400 73,600 Total 502,800 780,400 669,100 1,024,800 a Includes nonlisted chemicals.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 1.10 Major Chemical Producers Based on Sales (in Millions of U.S. Dollars)
Producer 1985 1990 1994 2000
United States DuPont 11,300 15,600 16,800 28,400 Dow Chemical 9500 14,700 14,100 23,000 Exxon (now Exxon-Mobile) 6700 11,200 11,000 21,500 Monsanto 5200 5700 5900 3900 Union Carbide 4000 7600 4900 6500 Shell Oil 3300 3700 4100 6300 Celanese (now Hoechst Celanese) 3300 5500 7000 2800 W. R. Grace 2900 3600 3200 1600 Chevron (now Chevron Phillips) 2600 3300 3100 7600 BASF 2600 4400 4300 7800 Eastman Kodak (now Eastman Chemical) 2300 3600 4300 5300 General Electric 2300 5200 5700 7800 Phillips Petroleum (now Chevron Phillips) 2300 2100 2800 Mobil (now Exxon-Mobil) 2300 4100 4200 Rohm & Haas 2000 2800 3500 6000 Air Products 1700 2600 3200 5200 Occidental Petroleum 1600 5000 4700 3800 Ciba 1500 2000 2800 2000 Ashland Oil 1500 2200 2900 1300 B. F. Goodrich 1400 1900 1100 1200 FMC 1300 1600 1900 2100 ICI Americas — — 4000 3,300 Praxair 5000 IMC Global 2100 Solutia 3200 Dow Corning 2800 Potash Corp. of Sask. 2200 Hercules 3200 Huntsman Chemical — — 3400 8000 Akzo-Nobel — — 3000 3300 Equistar 7500 Totalfina Elf 4800 Lyondell 4000 Nova 3900 PPG 6300 BP 5100 Europe Bayer (Germany) 15,600 26,800 28,500 BASF (Germany) 15,100 28,700 33,100 Imperial Chemical Inds. (U.K.) 13,900 15,400 11,700 DSM (Netherlands) 7300 4900 7500 Akzo (Netherlands) 5400 12,200 12,900 Norsk Hydro (Norway) 4900 10,100 17,800 Solvay (Belgium) 3800 7800 8200 Roche (Switzerland) 3600 10,800 17000 Ciba (Switzerland) — 16,100 4700
(continued)
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 1.10 Continued
Producer 1985 1990 1994 2000
Europe Degussa (Germany) — 8500 18,700 EniChem (Italy) — 7100 5500 Aventis (France) 20,500 Air Liquid (France) 7500 Syngenta (Switzerland) 7200 Rhodia (France) 6800 Clairant (Switzerland) 6300 Merch (Germany) 6200 Japan Mitsubishi Chemical Industries 3960 8500 16,200 Asahi Chemical Industries 3910 9600 11,800 Sumitomo Chemical 3220 5500 9700 Toray Industries 3200 5100 10,000 Mitsui Toatsu Chemicals 2100 3700 8700 Teijin 2100 3200 7100 Showa Denko 2100 4400 6900 Dainippon 9100 Shin-Etsu 7500 Canada DuPont Canada 870 1230 1500 Nova Corp. — 2700 3900 Methanex — 1500 1100 Potash Corp. 2200 Agrium 1900
Thus, polymers play a critical role in our everyday lives, actually forming the basis for both plant and animal life, and represent an area where chemists continue to make important contributions.
SUMMARY After reading this chapter, you should understand the following concepts. 1. Polymers or macromolecules are giant molecules with molecular weights at least 100 times greater than those of smaller molecules such as water or methanol. 2. If we disregard metals and inorganic compounds, we observe that practically everything else in this world is polymeric. This includes the protein and nucleic acid in our bodies, the fibers we use for clothing, the protein and starch we eat, the elastomers in our automobile tires, and the paint, plastic wall and floor coverings, foam insulation, dishes, furniture, pipes, and so forth in our homes. 3. In spite of the many varieties of fibers, elastomers, and plastic, they all have a similar structure and are governed by the same theories. Linear polymers, such as high-density polyethylene (HDPE), consist of long chains made up of thou- sands of covalently bonded carbon atoms. The repeating unit for HDPE is repre- sented as [CH2CH2]n, where n is the number of repeating units.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. 4. Most linear polymers such as HDPE are thermoplastic, i.e., they may be softened by heat and hardened by cooling in a reversible physical process. However, linear polymers like cellulose, which have very strong intermolecular forces (hydrogen bonds), cannot be softened by heating below the decomposition tem- perature. 5. Thermoset polymers are crosslinked and cannot be softened by heating. Thermo- plastics such as natural rubber and A-stage resole Bakelite resins can be trans- formed to thermosetting polymers by the introduction of crosslinks between the polymer chains. 6. Early developments in polymer technology were empirical because of a lack of knowledge of polymer science. Advancements in polymer technology were rapid in the 1930s and 1940s because of the theories developed by Staudinger, Carothers, Mark, and other polymer scientists. 7. Thermoplastic resole resins that may be thermoset by heating are obtained by heating phenol and formaldehyde on the alkaline side. Novolacs are obtained when an insufficient amount of formaldehyde is reacted in acid solution. Novo- lacs are converted to infusible plastics by heating with hexamethylenetetramine.
GLOSSARY ABS: A polymer produced by the copolymerization of acrylonitrile, butadiene, and styrene. acetal: A polymer produced by the polymerization of formaldehyde. alkyd: A polyester produced by the condensation of a dihydric alcohol, such as ethylene glycol, and a dicarboxylic acid, such as phthalic acid, in the presence of controlled amounts of an unsaturated monofunctional organic acid, such as oleic acid. A-stage: A linear resole resin. Bakelite: A polymer produced by the condensation of phenol and formaldehyde. biopolymer: A naturally occurring polymer, such as protein. buna: Copolymer of butadiene and styrene or acrylonitrile. butyl rubber: A copolymer of isobutylene and isoprene. cellulose: A naturally occurring carbohydrate polymer consisting of repeating glucose units. cellulose acetate: The ester of cellulose and acetic acid. cellulose nitrate: The product obtained by the reaction of nitric acid and sulfuric acid with cellulose; erroneously called nitrocellulose. The product is classified as primary, secondary, or tertiary according to how many groups in each repeating anhydroglu- cose unit in cellulose are nitrated. cis: A geometric isomer with both groups on the same side of the ethylenic double bond. collodion: A solution of cellulose nitrate in an equimolar mixture of ethanol and ethyl ether. colloid: An aggregate 10 9 to 10 7 m long; an aggregate of smaller particles. coumarone-indene resins: Polymers produced by the polymerization of distillation resi- dues. covalent bond: Chemical bonds formed by the sharing of electrons of the bonded atoms such as the carbon atoms in graphite or diamonds. cross-links: Covalent bonds between two or more linear polymeric chains. crystallites: Aggregates of polymers in crystalline form. C-stage: A crosslinked resole resin.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. cuprammonia rayon: Rayon produced from a solution of cellulose in a copper ammonia hydroxide solution. denaturation: The change in properties of a protein resulting from the application of heat or the addition of a foreign agent, such as ethanol. ebonite: Hard rubber; highly crosslinked natural rubber (NR). elastomer: A rubber. filament: The individual extrudate emerging from the holes in a spinneret. functionality: The number of reactive groups in a molecule. Galalith: A plastic produced by molding casein. glyptal: A polyester produced by the condensation of glycerol and phthalic anhydride. hydrogen bonds: Very strong forces resulting from the attraction of hydrogen atoms in one molecule with an oxygen or nitrogen atom in another molecule. These forces may also be present as intramolecular forces in macromolecules. intermolecular forces: Secondary valence forces between molecules. intramolecular forces: Secondary valence forces within a molecule. linear: A continuous chain, such as HDPE. macromolecule: A polymer. natural rubber, or NR (Hevea brasiliensis): Polyisoprene obtained from rubber plants. novolac: A thermoplastic phenol-formaldehyde resin prepared by the condensation of phenol and a small amount of formaldehyde on the acid side. Novolacs may be advanced to thermoset by heating with formaldehyde, which is usually obtained by the thermal decomposition of hexamethylenetetramine. NR: Natural rubber. nylon-66 (or nylon-6,6): A polyamide produced by the condensation of adipic acid [HOOC(CH2)4COOH] and hexamethylenediamine [H2N(CH2)6NH2]. oligomer: A very low molecular weight polymer in which the number of repeating units (n) equals 2 to 10 (oligos is the Greek term for few). plasticizer: An additive that reduces intermolecular forces in polymers. polymer: A giant molecule (or macromolecule) made up of multiple repeating units, such as polyethylene, in which at least 1000 ethylene units (MCH2CH2M) are joined together by covalent bonds. The word is derived from the Greek words meaning many parts. polymer age: An age when the use of polymers is emphasized, as in the twentieth century. protein: A polymer made up of many amino acid repeating units, i.e., a polyamide. Raoult’s law: A law that states that colligative properties of solutions, such as osmotic pressure and changes in vapor pressure, are related to the number of solute molecules present. rayon: Regenerated cellulose in the form of filaments. resole: A condensation product produced by the reaction of phenol and formaldehyde under alkaline conditions. shellac: A resin secreted by small coccid insects. spinneret: Small holes through which a solution or molten polymer is extruded in order to form filaments for fibers. tanning: Crosslinking of proteins by the reaction with crosslinking agents such as tannic acid. thermoplastic: A linear polymer that may be softened by heat and cooled in a reversible physical process. thermoset plastic: A network polymer usually obtained by crosslinking a linear polymer. Thiokol: A polyethylene sulfide elastomer.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. viscose: A solution of cellulose xanthate produced by the reaction of alkali cellulose and carbon disulfide. viscosity: The resistance to flow as applied to a solution or a molten solid. vital force concept: A hypothesis that stated that organic compounds could be produced only by natural processes and not in the laboratory. vulcanization: The process in which natural rubber is crosslinked by heating with sulfur.
EXERCISES 1. Name six polymers that you encounter daily. 2. Which would be more likely to be softened by heat? (a) (1) unvulcanized rubber, or (2) ebonite. (b) (1) A-stage, or (2) C-stage resole (c) (1) cellulose, or (2) cellulose acetate. 3. Name a polymer having the following repeating units: (a) ethylene (MCH2CH2M) (b) phenol and formaldehyde residual units. (c) amino acid residual units 4. In which of the following polymers will hydrogen bonding predominate? (a) natural rubber (NR). (b) linear polyethylene (HDPE) (c) cellulose. (d) cellulose nitrate 5. Which of the following products are polymeric? (a) water (b) wood (c) meat (d) cotton (e) rubber tires (f) paint 6. Which of the following is a thermoset or cross-linked polymer? (a) cellulose (b) unvulcanized rubber (c) A-stage resole (d) cellulose nitrate (e) molded Bakelite (f) ebonite 7. Which of the items in question 6 are thermoplastic? 8. If you were Staudiner, how would you answer your critical colleagues? 9. Why are so many outstanding polymer scientists alive today? 10. What percentage of polymer science students receive job offers after graduation? 11. What is the molecular weight of H(CH2CH2)1000H? 12. What is the principal difference between rayon and cellophane? 13. Which is the more heat stable, a resole or a novolac phenolic (Bakelite) resin?
BIBLIOGRAPHY Allcock, H. R. Lampe, F. W. (1990), Contemporary Polymer Chemistry, 2nd ed., Wiley, NY. Allen, P. W. (1972): Natural Rubber and Synthetics, Halsted, New York.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Bassett, D. C. (1988): Developments in Crystalline Polymers, Elsevier, New York. Billmeyer, F. W. (1984): Textbook of Polymer Science, 3rd ed., Wiley Interscience, New York. Brown, R. P. (1989): Handbook of Plastics Test Methods, 2nd ed., Wiley, New York. Brydson, J. A. (1989): Plastic Materials, 5th ed., Newmes-Butterworth, Kent, England. Callister, W. D. (2000): Materials Science and Engineering, 5th ed., Wiley, New York. Callister, W. D. (1997): Materials Scienceand engineering: an Introduction, 4th Ed., Wiley, NY. Campbell, I. M. (2000): Introduction to Synthetic Polymers, Oxford, New York. Campbell, I. M. (1994), Introduction to Synthetic Polymers, Oxford University Press, Cary, NC. Carraher, C. E., Gebelein, C. G. (1982): Biological Activities of Polymers, ACS, Washington, D.C. Carraher, C. E., Seymour, R. B. (1985): Fundamentals of polymer science, Applied Polymer Science, ACS Washington, D.C. Challa, G. (2000): Advanced Polymer Chemistry: A Problem Solving Guide, Marcel Dekker, New York. Challa, I. (1993): Polymer Chemistry: An Introduction, Prentice-Hall, Englewood Cliffs, New Jersey. Cowie, J. M. G. (1991): Polymers: Chemistry and Physics of Modern Materials, 2nd ed., Blackie, London. Craver, C., Carraher, C. (2000): Applied Polymer Science, Elsevier, New York. Culbertson, B. M., Pittman, C. U. (1983): New Monomers and Polymers, Plenum, New York. Ebewele, R. O. (1998): Polymer Science and Technology, CRC Press, Boca Raton, FL. Ehrenstein, G. (2001): Polymeric Materials, Hanser Gardner, Cincinnati, OH. Elias, H. G. (1984): Macromolecules, Vols. 1 and 2, Plenum, New York. Elias, H. G. (1997): An Introduction to Polymers, Wiley, NY. Flory, P. J. (1953): Principles of Polymer Chemistry, Chap. 1, Cornell University Press, Ithaca, New York. Gebelein, C. G., Carraher, C. E. (1985): Bioactive Polymeric Systems: An Overview, Plenum, New York. ——. (1985): Polymeric Materials in Medication, Plenum, New York. Glanville, A. B. (1973): The Plastics Engineers Data Book. Industrial Press, New York. Golding, B. (1959): Polymers and Resins, Van Nostrand, Princeton, New Jersey. Goodman, S. H. (1986): Handbook of Thermoset Plastics, Noyes, Park Ridge, New Jersey. Grosberg, A. Khokhlov, A. R. (1997), Giant Molecules, Academic Press, Orlando, FL. Hummel, R. E. (1998): Understanding Materials Science: History, Properties, Applications, Springer-Verlag, NY. Kirshenbaum, G. S. (1973): Polymer Science Study Guide, Gordon and Breach, New York. Korschwitz, J. (1990): Polymer Characterization and Analysis, Wiley, New York. Lai, J. H. (1989): Polymers for Electronic Applications, CRC, Boca Raton, Florida. Lee, L. (1990): Adhesive Bonding, Plenum, New York. Lemstra, P. J. (1989): Integration of Fundamental Polymer Science and Technology, Elsevier, New York. Mark, H. F. (1985): Applied Polymer Science, (R. W. Tess and G. Paehlein, Eds.), Polymeric Materials Division of ACS, Washington, D.C., Chap. 1. Mebane, R., Rybolt, T. (1995): Plastics and Polymers, TFC Pub., New York. Misral, G. S. (1993): Introductory Polymer Chemistry, Halsted, New York. Morawetz, H. (1985): Origins and Growth of a Science, Polymers, Wiley, New York. Morton, M. (1987): Rubber Technology, 3rd ed., Van Nostrand-Reinhold, New York. Nicholson, J. W. (1997), The Chemistry of Polymers, Royal society of Chemistry, London. Odian, G. (1991): Principles of Polymerization, Wiley, New York. Paul, D. R., Sperling, L. H. (1986): Multicomponent Polymer Materials, ACS, Washington, D.C. Plate, N. A., Shibaev, V. P. (1987): Comb-Shaped Polymers and Liquid Crystals, Plenum, New York. Powers, P. O. (1943): Synthetic Resins and Rubbers, Chap. 1, John Wiley, New York. Prasad, P., Nigam, J. (1992): Frontiers of Polymer Research, Plenum, New York.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Ravve, A. (2000): Principles of Polymer Chemistry, Kluwer, New York. Rodriguez, F. (1989): Principles of Polymer Systems, 3rd ed., Hemisphere, New York. Rodriguez, F. (1996): Principles of Polymer Systems, 4th Ed., Taylor and Francis, Philadelphia, PA. Rosen, S. L. (1993): Fundamental Principles of Polymeric Materials, 2nd ed. Wiley, New York. Salamone, J. C. (1998): Concise Polymeric Materials Encyclopedia, CRC Press, Boca Raton, FL. Sandler, S. R., Karo, W. (1997): Polymer Synthesis, Academic Press, New York. Sandler, S., Karo, W., Bonesteel, J., Pearce, E. M. (1998): Polymer Synthesis and Characterization, Academic Press, Orlando, FL. Schwartz, M. (1996): Emerging Engineering Materials, Technomic, Lancaster, PA. Saunders, K. J. (1988): Organic Polymer Chemistry, Routledge Chapman & Hall, Boston. Seeman, J. (1993): Herman Mark—From Small Organic Molecules to Large: A Century of Progress, ACS, Washington, D.C. Seymour, R. B. (1971): Introduction to Polymer Chemistry, McGraw-Hill, New York, Chap. 1. ——. (1975): Modern Plastics Technology, Reston, Reston, Virginia. ——. (1982): Plastics vs Corrosives, Wiley, New York. ——. (1990): Engineering Polymer Sourcebook, McGraw-Hill, New York. Seymour, R. B., Carraher, C. E. (1984): Structure–Property Relationships in Polymers, Plenum, New York. Seymour, R. B., Carraher, C. E. (1990): Giant Molecules, Wiley, New York. Seymour, R., Carraher, C. (1997) Introduction a la Quimica de los Polymeros, Editorial Reverte, S. A., Barcelona, Spain. Seymour, R. B., Kirshenbaum, G. S. (1986): High Performance Polymers, Elsevier, New York. Seymour, R. B., Mark, H. F. (1988): Applications of Polymers, Plenum, New York. Seymour, R. B., Stahl, G. (1982): Macromolecular Solutions, Pergamon, Elmsford, New York. MMM. (1987): Pioneers in Polymer Science, Litarvan Lit., Denver, Colorado. Sorenson, W., Sweeny, F., Campbell, T. (2001): Preparative Methods in Polymer Chemistry, Wiley, New York. Sperling, L. (2001): Introduction to Physical Polymer Science, 2nd ed., Wiley, New York. Sperling, L. H. (1986): Introduction to Physical Polymer Science, Wiley, New York. Staudinger, H. (1932): Die Hochmolekularen, Springer-Verlag, Berlin. Stevens, M. P. (1998): Polymer Chemistry, 2nd ed. Oxford University Press, Oxford, England. Sun, S. (1994): Chemistry of Macromolecules: Basic Principles and Issues, Wiley, New York. Tadokoro, H. (1990): Structure of Crystalline Polymers, Krieger, New York. Tanaka, T. (1999): Experimental Methods in Polymer Science, Academic Press, New York. Thrower, P. (1996): Materials in Today’s World, 2nd Ed., McGraw-Hill, NY. Tonelli, A. (2001): Polymers Inside Out, Wiley, New York. Tschoegl, N. W. (1989): Phenomenological Theory of Linear Viscoelastic Behavior, Springer-Ver- lag, New York. Ulrich, H. (1988): Raw Materials for Industrial Polymers, Oxford University Press, Oxford, England. Vogl, O. (1988): Polymer Science in the Next Decade, Wiley, New York. Walton, D. (2001): Polymers, Oxford, New York. Yasuda, H. (1985): Plasma Polymerization, Academic Press, New York.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. 2 Polymer Structure (Morphology)
The size and shape of polymers are intimately connected to their properties. The shape of polymers is also intimately connected to the size of the various units that make up the macromolecules and the various primary and secondary bonding forces that are present within the chain and between chains. This chapter covers the basic components that influ- ence polymer shape or morphology. We generally describe the structure of both synthetic and natural polymers in terms of four levels of structure. The primary structure describes the precise sequence of the individual atoms that compose the polymer chain. For polymers where there is only an average structure, such as proteins, polysaccharides, and nucleic acids, a representative chain structure is often given. The structure can be given as a single repeat unit such that the full polymer structure can be obtained by simply repeating the repeat unit 100, 500, or 1,000 times, depending on the precise number of repeat units in the polymer chain. For poly(vinyl chloride), PVC, this is
R ( CH2 CH ) RorR ( CH2 CH(Cl) ) Ror (CH2 CH ) ͉͉ Cl Cl Or some fuller description of the primary structure may be given such as that below for three repeat units of PVC where the particular geometry about each chiral carbon is given.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. The ends may or may not be given depending on whether they are important to the particular point being made. Thus, for the single PVC repeat unit given above the end groups may given as follows:
CH3 CH ( CH2 CH ) CH2 CH2Cl ͉͉
C1 C1 The repeat unit for cellulose is
The secondary structure describes the molecular shape or conformation of the poly- mer chain. For most linear polymers this shape approaches a helical or “pleated skirt” (or sheet) arrangement depending on the nature of the polymer, treatment, and function. Examples of secondary structures appear in Figs. 2.15 and 2.20. The tertiary structure describes the shaping or folding of the polymer. Examples of this are found in Figs. 2.9, 2.16, and 2.21–2.22. Finally, the quaternary structure represents the overall shape of groups of the tertiary structures where the tertiary structures may be similar or different. Examples are found in Figs. 2.21–2.22.
2.1 STEREOCHEMISTRY OF POLYMERS The terms “memory” and “to remember” are similar and used by polymer chemists in similar, but different, ways. The first use of the terms “memory” and “to remember” involves reversible changes in the polymer structure usually associated with stress–strain deformation of a rubber material where the dislodged, moved polymer segments are con- nected to one another through chemical and physical crosslinks, so that once the particular stress/strain is removed the polymer returns to its original, prestress–strain arrangement of the particular polymer segments. Thus, the polymer “remembers” its initial segmental arrangement and returns to it through the guiding of the crosslinks. The second use involves nonreversible changes of polymer segments and whole chain movements also brought about through stress–strain actions. These changes include any synthetic chain and segmental orientations as well as postsynthesis changes including fabrications effects. These changes involve “permanent” changes in chain and segmental orientation and in some ways these changes represent the total history of the polymer materials from inception (synthesis) through the moment when a particular property or behavior is measured. These irreversible or nonreversible changes occur with both cross- linked and noncrosslinked materials and are largely responsible for the change in polymer property as the material moves from being synthesized, processed, fabricated, and used in what ever capacity it finds itself. Thus, the polymeric material “remembers” its history with respect to changes and forces that influence chain and segmental chain changes. The ability of polymers to remember and have a memory are a direct consequence of their size. We can get an idea of the influence of size in looking at the series of methylene hydrocarbons as the number of carbon atoms increases. For low numbers of carbons,
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. Table 2.1 Typical Properties of Straight Chain Hydrocarbons
Average number of Boiling Physical state Typical carbon atoms range,°C Name at room temp. uses
1–4 30 Gas Gas Heating 5–10 30–180 Gasoline Liquid Automotive fuel 11–12 180–230 Kerosene Liquid Jet fuel, heating 13–17 230–300 Light gas oil Liquid Diesel fuel, heating 18–25 305–400 Heavy gas oil Viscous liquid Heating 26–50 Decomposes Wax Waxy Wax candles 50–1000 Decomposes Tough waxy Wax coatings of food to solid containers 1000–5000 Decomposes Polyethylene Solid Bottles, containers, films 5000 Decomposes Polyethylene Solid Waste bags, ballistic wear, fibers, automotive parts, truck liners
methane, ethane, propane, butane, the materials are gases at room temperature. For the next groupings (Table 2.1) the materials are liquids. The individual hydrocarbon chains are held together by dispersion forces that are a sum of the individual methylene and end group forces. There is a gradual increase in boiling point and total dispersion forces for the individual chains until the materials become waxy solids such as found in bees’ waxes and finally where the total dispersion forces are sufficient to be greater than individual carbon–carbon bond strengths, so that the chains decompose prior to their evaporation. Finally, the chain lengths are sufficient to give the tough and brittle solids we call polyethyl- ene. It is interesting to note that these long chain straight chain hydrocarbons become very strong but brittle. They are crystalline—and as with most other crystalline materials, such as rocks and diamonds, they are strong but brittle. Fortunately, synthetic polyethylene contains both crystalline regions where the polymer chains are arranged in ordered lines and regions where the chains are not arranged in ordered lines. These latter arrangements are imposed on the polyethylene because of the presence of branching in the linear polymer backbone. They are referred to as amorphous regions and are responsible for allowing the polyethylene to have some flexibility. Thus, many polymers contain both amorphous and crystalline regions that provide both flexibility and strength. The polyethylene chains described in Table 2.1 exhibit irreversible and, when appro- priate crosslinking is present, reversible memory. As a side note, low-molecular-weight polyethylene with appreciable side branching has a melting range generally below 100 C, whereas high-molecular-weight polyethylene with few branches has a melting range approaching the theoretical value of about 145 C. High-density polyethylene (HDPE), formerly called low-pressure polyethylene [H(CH2CH2)nH], like other alkanes [H(CH2)nH], may be used to illustrate a lot of polymer structure. As in introductory organic chemistry, we can comprehend almost all of the complex organic compounds if we understand the basic chemistry and geometry. High-density polyethylene, like decane [H(CH2)10H] or paraffin [H(CH2)ϳ50H], is a largely linear chain-like molecule consisting of catenated carbon atoms bonded cova-
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. lently. The carbon atoms in all alkanes, including HDPE, are joined at characteristic tetrahedral bond angles of approximately 109.5 . While decane consists of 10 methylene groups (CH2), HDPE may contain more than 1000 of these groups. While we use the term normal straight chain or linear for alkanes, we know that because of the characteristic bond angles the chains are zigzag-shaped. The distance between the carbon atoms is 1.54 angstroms (A˚ ) or 0.154 nanometers (nm). The apparent zigzag distance between carbon atoms in a chain of many carbon atoms is 1.26 A˚ , or 0.126 nm. Therefore, the length of an extended nonane chain would be 8 (1.26 A˚ ), or 10.08 A˚ , or 1.008 nm. Likewise, the length of an extended chain of HDPE having 1000 repeat ethylene units or structural elements [H(CH2CH2)1000Hor H(CH2)2000H] would be 2520 A˚ or 252 nm. However, as shown by the magnified simulated structure in the diagram for HDPE (Fig. 2.1, top) because of rotation of the carbon–carbon
Figure 2.1 Magnified simulated structure of high-density polyethylene (HDPE), contrasted with the structural formula of decane.
Copyright © 2003 by Marcel Dekker, Inc. All Rights Reserved. bonds, these chains are seldom extended to their full contour length but are present in many different shapes, or conformations. Problem Determine the contour length of a polyethylene chain 1300 ethylene units long given the average zigzag distance between carbon atoms of 0.126 nm. There are two carbon atoms within the polymer chain backbone per repeat unit. Thus, per unit the average contour length is 2 0.126 nm 0.252 nm. The contour length is then 0.252 nm/unit 1300 units Ӎ 330 nm.
Each specific protein molecule has a specific molecular weight, like the classic small molecules, and is said to be monodisperse with respect to molecular weight. However, commercial synthetic polymers, such as HDPE, are made up of molecules of different molecular weights. Thus, the numerical value for n, or the degree of polymerization (DP), should be considered as an average DP and designated with an overbar, i.e., DP. Accord- ingly, the average molecular weight (M) of a polydisperse polymer will equal the product of the (average) DP and the molecular weight of the repeating unit or mer. In classic organic chemistry, it is customary to call a nonlinear molecule, like isobu- tane, a branched chain. However, the polymer chemist uses the term pendant group to label any group present on the repeating units. Thus, polypropylene
HCH3 ͉͉