Polymer Physics: Applications to Molecular Association and Thermoreversible Gelation,

Fumihiko
Tanaka
,
Cambridge U. Press
,
New York
, 2011. $130.00 (404 pp.). ISBN 978-0-521-86429-9

At its foundation, soft-matter science is supported by macromolecular physics, which is intimately linked with statistical mechanics and such phenomena as critical behavior and Brownian motion. A soft-matter scientist may wonder whether we really need any new books in polymer physics, given that we already have two brilliant works, Scaling Concepts in Polymer Physics by Pierre Gilles de Gennes (Cornell University Press, 1979) and The Theory of Polymer Dynamics by Masao Doi and Sam Edwards (Clarendon Press, 1988). Those masterpieces, faithful companions of any scholar in soft matter, may hardly be surpassed. Yet scientists who conclude that no more is needed would be wide of the mark.

In the past, polymer physics mainly dealt with nonspecific polymer–solvent interactions typified by short-range dispersion forces or, in the opposite limit, by long-range electrostatic effects in polyelectrolyte solutions. But with the expansion of polymer chemistry and the introduction of novel systems such as block copolymers, telechelic structures, and polymer microgels, scientists in the field must now consider how, for example, hydrogen bonding is affected by polarity and entropy. In addition, to understand the complex interplay between polymers, surfactants, and proteins, we will need to get a better handle on the aggregation behavior of amphiphilic molecules.

Bridging that gap, at least in part, is one of the goals of Fumihiko Tanaka’s Polymer Physics: Applications to Molecular Association and Thermoreversible Gelation. The book hardly aims to be comprehensive; rather it focuses on the topics specified in its restrictive subtitle. In addressing them, Tanaka is guided by his training as a physical chemist in the prestigious school of physicist Sam Edwards, who pioneered the use of Feynman diagrams to describe the statistical properties of disordered systems; Tanaka also acknowledges the informal but influential role played by Japanese mathematical physicist Ryogo Kubo.

Tanaka’s coherent and organic framework enables him to set very different systems in a common context and discuss their structures and phase behaviors in depth, at least within a Flory–Huggins mean-field approach. The book fully exploits percolation and scaling concepts in its discussion of network structure and topology. It also meticulously discusses thermoreversible gelation driven by conformational changes, a phenomenon of particular value for understanding the phase behavior of protein solutions. Also noteworthy is the author’s attempt to provide a solid background for micellar aggregation in amphiphilic polymer solutions, a topic still not fully understood due to the subtle interplay between aggregate morphology and intermicellar interactions. As a physicist mostly dealing with colloids, I also appreciated the thoughtful discussion of cooperative hydration effects in poly(N-isopropylacrylamide) microgels, which are extensively exploited as model systems of soft spheres whose size can be thermally tuned.

Of course, the book’s narrow focus leaves out many interesting questions. For example, it only sketches the relation between the formation of polymer networks and depletion-induced gelation in colloids. Its analysis of dynamic effects is confined to macroscopic rheology, and microscopic dynamics in arrested systems, currently a matter of great interest in soft-matter science, gets only a brief treatment. Nonspecialists may wish for more attention to the general theory of polyelectrolytes and possibly a more detailed comparison with experimental data on gelation. I admit, however, that expecting this laudably compact book to be exhaustive would be too much.

To my taste, Tanaka’s writing style is a bit too formal and dry, and he rarely inspires readers to use their intuition. That approach, together with the advanced level of the book and the uninviting price of its hardbound edition—I really hope for a paperback—makes Polymer Physics poorly suited for most educational purposes. Nevertheless, I found its original approach to polymer conformation quite instructive. For instance, the concept of a Langevin chain, essential for any discussion of nonlinear elasticity, is introduced at the start. The detailed parallel between thermoreversible gelation and Bose–Einstein condensation is another gem I may use as suggested reading in the courses I teach on soft-matter physics.

As a valuable technical book and as a source of inspiration when teaching a graduate-level course, Polymer Physics fully deserves its place on the bookshelves of soft-matter scientists, and maybe even in the libraries of other condensed-matter physicists and chemists.