The two feature articles in this issue present numerous contrasts, but both reflect the vitality of research in polymer science today. David Tirrell and co-authors paint a picture of how the techniques of molecular biology may be applied to the synthesis of novel “proteinlike” polymers with control over molecular weight, composition, and stereoregularity that is unprecedented in the realm of traditional polymer chemistry. Wolfgang Knoll turns his attention to ultrathin polymer films with thicknesses comparable to molecular chain dimensions and demonstrates how evanescent wave optical methods may be used to provide spectroscopic as well as imaging information on the characterization of these “restricted geometry” systems.

Both authors address the issue of supermolecular structure, whether approached from the synthetic or physical chemical viewpoints. Tirrell describes a series of target polymers, expressed by genetically engineered microorganisms, which may provide a fundamental understanding and control over chain folding, a critical morphological feature governing solid-state behavior of synthetic polymers. Knoll analyzes the fundamentals of evanescent wave optical methods for interrogating the molecular organization in polymer films that have considerable potential in electronic or photonic applications.

Polymerization reactions are generally divided into two broad classes: step growth or polycondensation reactions (examples would include the synthesis of polyamides and polyesters), and chain growth processes such as those used to prepare polyethylene or polystyrene. These processes are illustrated schematically in Figure 1.

The statistical nature of step and chain growth polymerization processes ensures that the products of such reactions must be heterogeneous. Conventional polymeric materials thus consist of mixtures of chains, often characterized by relatively broad distributions of chain length or composition. In many materials applications, this kind of molecular heterogeneity is advantageous since it suppresses crystallization and helps to preserve desirable properties such as optical clarity or elasticity. On the other hand, synthetic developments that afford improved control of macromolecular architecture have had profound impact on materials science and technology. As examples, one can cite the discovery of Ziegler-Natta polymerization, now used to prepare billions of pounds per year of crystalline polyolefins, or the development of living anionic polymerization of olefins, which led directly to block copolymers and the commercially important thermoplastic elastomers.

The advent of recombinant DNA methods has provided a basis for developing polymeric materials characterized by essentially absolute uniformity of chain length, sequence, and stereochemistry. This article outlines the principles governing the cloning and expression of artificial genes, and examines the potential role of artificial proteins in polymer materials science.

Among the numerous experimental techniques available for comprehensive materials characterization, light optical methods play an outstanding role. Based, in all cases, on the interaction of electromagnetic radiation with matter in various configurations (e.g., for absorption, thermalization, re-emission, elastic and inelastic scattering, or for microscopic imaging experiments), optical techniques provide detailed information about many structural, electronic, and other materials properties. Typically, propagating electromagnetic waves (“normal” photons) are used for these studies, and a broad spectrum of powerful optical instruments is available for investigating all kinds of bulk materials. However, where thinner and thinner samples are of interest—eventually only one monomolecular layer (or even less) thick—some of these standard techniques lack the sensitivity necessary to be useful. On the other hand, there is a growing (nano)tech-nological demand for thin-film preparations especially in the polymeric materials area, e.g., as thin lubricating, isolation, or protective coatings, for integrated or nonlinear optical devices, or to increase the biocompatibility of inorganic materials. This has stimulated the development of novel optical techniques with increased sensitivity, specificity, and spatial resolution. For interfacial properties and thin film samples, the use of a different kind of light, called evanescent waves, has proved in recent years to be particularly helpful because their high surface specificity allows sensitive monitoring of the properties of interfaces and thin layers without the interference of information from the bulk.

The U.S. Environmental Protection Agency (EPA) is one of several agencies that serve as members of the Federal Coordinating Council of Science, Engineering, and Technology. In this role, EPA chairs the Environmental, Safety, and Health Work Group of the Committee on Materials. One of the primary purposes of the Committee on Materials is to strengthen the government-industry:university partnership in materials research. Strengthening and building this partnership is also one of the goals of the Materials Research Society. You bring together an interdisciplinary group of scientists and engineers from industry, government, and academia to exchange ideas on the forefront of materials research.

A recent National Research Council report, Materials Science and Engineering for the 1990s: Maintaining Competitiveness in the Age of Materials, identified six major science and engineering initiatives. One of these six initiatives was the environment. I believe that we will see, over the next few years, a major thrust in materials research to develop environmentally benign or “environmentally friendly” materials—materials that are less toxic and less polluting and do not deplete scarce natural resources, materials that have longer useful lives, and materials that can be recycled and require less energy to manufacture.