Deciphering the tangled web
Another book on polymer structure? This one contains a few chapters that are not only well thought out, but also original in their approach, allowing readers to rapidly gain a sense of what’s what.
March 20, 2008
Liliane Léger, Université Paris-Sud 11, France
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Richard A. Pethrick |
Richard A. Pethrick has used his years of teaching to produce a book aimed at courses on molecular organization and structure in polymer materials.
His first interest is to gather, in a single book, information usually available from as many monographs as there are chapters here. A second merit of the book is to present polymer crystallization in connection with other systems, such as small molecules that form crystals, plastic crystals, liquid crystals, and so on. Thus the specific behavior of polymer systems containing large, long macromolecules comes to light through comparison with simpler systems.
As someone who teaches polymer crystallization myself, I find it particularly useful to take the time to introduce the basic concepts of nucleation and crystal growth for small molecules, and only then apply these concepts to polymers. This certainly helps the reader to think in terms of basic concepts, before entering the detailed description of polymer systems.
Textbooks on polymer materials often remain strictly focused on polymers, introducing the notions of nucleation and growth mixed in with historical considerations. This can give students the idea that polymer physics is a discrete field.
The chapter on polymer crystallization and growth is a key one. Polyethylene is chosen to illustrate the successes and limitations of the different models of crystallization, allowing one to focus on essential facts: chain folding, chain entanglements, etc.
A chapter on glasses and amorphous materials follows, again using a single discussion to describe small molecule glass-forming systems and polymers. Otherwise, the treatment of glass transition remains classical.
The real originality of Pethrick’s approach rests on the fact that the description of polymer crystal morphology and the methods used to characterize it are gathered into a single chapter (Chapter 5). The reader is thus invited to discover the major morphologies of polymer crystals through a number of figures that, at the same time, give a flavor of what can be obtained from the various techniques. A comparison of these techniques is supported by easy to use tables and is a great help for any nonspecialist faced with a choice of experimental tools.
A short and more original chapter (Chapter 8) is devoted to polymer blends. This is not usual in textbooks on polymers despite polymer blends having quite important practical applications. This self-consistent chapter introduces the basic thermodynamics of phase separation in binary mixtures, before applying them to polymers. Several applications, such as high impact polystyrene of rubber toughened epoxy resins are described, and the chapter concludes with a discussion of organized structures obtained with block copolymers, another rapidly growing field of polymer materials.
Chapter 9 is devoted to molecular surfaces. It first presents a thermodynamic approach to surface energy and wettability, followed by a description of a range of experimental techniques for surface characterization. The reader can rapidly gain a sense of what can be deduced from what.
The very short chapter on polymer surfaces at the end of the book is, in my opinion, less convincing. I found it disappointing and much too short to be really informative. Real applications are not mentioned (for example, nothing is said about adhesion phenomena or about nanopatterning using copolymer structures at interfaces).
I feel the same way about the last chapter on colloids and molecular organization in liquids, which is another rapid overview. Pethrick tentatively justifies this by remarking that in many biological systems or polar polymers the organization observed in the solid is a consequence of a preexisting organization in the liquid phase, but more is needed for the chapter to be really useful.
Except for these two last chapters, the book is really well thought out and clearly written. I thoroughly recommend it to anyone wishing to find his or her way through the complicated area of polymer materials.