Polymer Chemistry

Timothy P. Lodge, Paul C. Hiemenz

• Editore: CRC Press
• Anno: 2020
• ISBN:
  9781466581661
• Edizione: 3
• Argomento: Scienze fisiche
• Categoria: Chimica

A well-rounded and articulate examination of polymer properties at the molecular level, Polymer Chemistry focuses on fundamental principles based on underlying chemical structures, polymer synthesis, characterization, and properties. It emphasizes the logical progression of concepts and provide mathematical tools as needed as well as fully derived problems for advanced calculations.

The much-anticipated Third Edition expands and reorganizes material to better develop polymer chemistry concepts and update the remaining chapters. New examples and problems are also featured throughout.

This revised edition:

• Integrates concepts from physics, biology, materials science, chemical engineering, and statistics as needed
• Contains mathematical tools and step-by-step derivations for example problems
• Incorporates new theories and experiments using the latest tools and instrumentation and topics that appear prominently in current polymer science journals
• The number of homework problems has been greatly increased, to over 350 in all
• The worked examples and figures have been augmented
• More examples of relevant synthetic chemistry have been introduced into Chapter 2 ("Step-Growth Polymers")
• More details about atom-transfer radical polymerization and reversible addition/fragmentation chain-transfer polymerization have been added to Chapter 4 ("Controlled Polymerization")
• Chapter 7 (renamed "Thermodynamics of Polymer Mixtures") now features a separate section on thermodynamics of polymer blends
• Chapter 8 (still called "Light Scattering by Polymer Solutions") has been supplemented with an extensive introduction to small-angle neutron scattering

Polymer Chemistry, Third Edition offers a logical presentation of topics that can be scaled to meet the needs of introductory as well as more advanced courses in chemistry, materials science, polymer science, and chemical engineering.

1Introduction to Chain Molecules

1.1Introduction

“I am inclined to think that the development of polymerization is perhaps the biggest thing chemistry has done, where it has had the biggest impact on everyday life” [1]. This assessment of the significance of polymer chemistry to modern society was offered 40 years ago by Lord Todd (President of the Royal Society and 1957 Nobel Laureate in Chemistry), and subsequent developments have only reinforced this sentiment. There is hardly an area of modern life in which polymer materials do not play an important role. Applications range from the everyday (e.g., packaging, toys, fabrics, diapers, nonstick cookware, pressure-sensitive adhesives) to demanding specialty uses (e.g., bulletproof vests, stealth aircraft, artificial hip joints, resorbable sutures). In many instances polymers are the main ingredients, and the ingredients whose characteristic properties are essential to the success of a particular technology: rubber tires, foam cushions and insulation, high-performance athletic shoes, clothing, and equipment are good examples. In other cases, polymers are used as additives at the level of a few percent by volume, but which nevertheless play a crucial role in the properties of the final material; illustrations of this can be found in asphalt (to suppress brittle fracture at low temperature and flow at high temperature), shampoo and other cosmetics (to impart “body”), automobile windshields (to prevent shattering), and motor oil (to reduce the dependence of viscosity on temperature, and to suppress crystallization).

For those polymer scientists “of a certain age,” the 1967 movie The Graduate [2] provided an indelible moment that still resonates today. At his college graduation party, the hero Benjamin Braddock (played by Dustin Hoffman) is offered the following advice by Mr. McGuire (played by Walter Brooke):

Mr. McGuire. I want to say one word to you. Just one word.

Benjamin. Yes, sir.

Mr. McGuire. Are you listening?

Benjamin. Yes, I am.

Mr. McGuire. Plastics.

In that period, the term “plastic” was often accompanied by negative connotations, including “artificial,” as opposed to “natural,” and “cheap,” as opposed to “valuable.” Today, in what we might call the “post-Graduate era,” the situation has changed. To the extent that the advice offered to Benjamin was pointing him to a career in a particular segment of the chemical industry, it was probably very sound advice. The volume of polymer materials produced annually has grown rapidly over the intervening years, to the point where today several hundred pounds of polymer materials are produced each year for each person in the United States. More interesting than sheer volume, however, is the breadth of applications for polymers. Not only do they continue to encroach into the domains of “classical” materials such as metal, wood, and glass (note the inexorable transformation of polymers from minor to major components in automobiles), but they also play a central role in many emerging technologies. Examples include plastic electronics, gene therapy, artificial prostheses, optical data storage, electric cars, fuel cells, and aircraft. In short, a reasonable appreciation of the properties of chain molecules, and how these result in the many desirable attributes of polymer-containing materials, is a necessity for a well-trained chemist, materials scientist, or chemical engineer today. At the same time, the prevalence of plastics has created some severe environmental challenges, which are just beginning to receive serious attention.

Science tends to be plagued by clichés, which make invidious comparison of its efforts; “they can cure such and such a dreaded disease, but they cannot do anything about the common cold” or “we know more about the surface of the moon than the bottom of the sea.” If such comparisons were popular in the 1920s, the saying might have been, “We know more about the structure of the atom than about those messy, sticky substances called polymers.” Indeed, Millikan's determination of the charge of an electron, Rutherford's idea of the nuclear atom, and Bohr's model of the hydrogen atom were all well-known concepts before the notion of truly covalent macromolecules was accepted. This was the case in spite of the great importance of polymers to human life and activities. Our bodies, like all forms of life, depend on polymer molecules: carbohydrates, proteins, nucleic acids, and so on. From the earliest times, polymeric materials have been employed to satisfy human needs: wood and paper; hides; natural resins and gums; fibers such as cotton, wool, and silk.

Attempts to characterize polymeric substances had been made, of course, and high molecular weights were indicated, even if they were not very accurate. Early workers tended to be more suspicious of the interpretation of the colligative properties of polymeric solutions than to accept the possibility of high molecular weight compounds. Faraday had already arrived at C₅H₈ as the empirical formula of “rubber” in 1826, and isoprene was identified as the product resulting from the destructive distillation of rubber in 1860. The idea that a natural polymer such as rubber somehow “contained” isoprene emerged, but the nature of its involvement was more elusive.

During the early years of the 20th century, organic chemists were enjoying success in determining the structures of ordinary-sized organic molecules, and this probably contributed to their reluctance to look beyond structures of...