David Turnbull's experiments and theoretical insights paved the way for much of our modern understanding of phase transitions in materials. In recognition of his contributions, this lecture will concentrate on phase transitions in a material system not considered by Turnbull, thin diblock copolymer films. Well-ordered block copolymer films are attracting increasing interest as we attempt to extend photolithography to smaller dimensions. In the case of diblock copolymer spheres, an ordered monolayer is hexagonal, but the ordered bulk is body-centered cubic (bcc). There is no hexagonal plane in the bcc structure, so a phase transition must occur as n, the number of layers of spheres in the film, increases. How this phase transition occurs with nand how it can be manipulated is the subject of the first part of my presentation. In the second part of the talk, I show that monolayers of diblock copolymer spheres and cylinders undergo order-to-disorder transitions that differ greatly from those of the bulk. These ordered 2D monolayers are susceptible to phonon-generated disorder as well as to thermal generation of defects, such as dislocations, which, while they are line defects in 3D, are point defects in 2D. The results are compared to the theories of melting of 2D crystals (spheres) and of 2D smectic liquid crystals (cylinders), a comparison that will allow us to understand most, but not all, of the features of these order-disorder transitions that occur as the temperature is increased.

Stardust, a NASA sample return mission, safely landed in the Utah desert in January 2006 after a seven-year mission, bringing with it the first cometary material from a known parent source, Comet 81P/Wild 2. One of the mission goals is to determine the starting material of the solar system. By sampling a comet, which has spent most of the past 4.6 Gyr beyond the orbit of Neptune, we expect to measure material presumed to be unaffected by the ignition of the sun. The Stardust spacecraft swept through the tail of the comet, collecting hundreds of micron-sized particles from that stream into aerogel, a low-density silica foam. An international team of materials scientists have studied the mineralogy, petrology, and elemental and isotopic abundance of these materials. Our group has studied elemental abundance using an x-ray microprobe; the morphology of the particles was examined using an x-ray microscope, which enables nanotomography of the particles while encased in aerogel. The unexpected conclusions are that much of the material from this comet was formed near the sun, after its ignition, and soon thereafter transported to the outer reaches of the solar system. These results have changed the way astrophysicists think about solar system formation.

Egyptian pigments include the most successful synthetic blue pigment made, which has been in use for more than 2500 years. The nature of some Egyptian pigments, such as malachite, azurite, green earth, and calcite are briefly reviewed. The principal artworks examined here are a group of several 26th Dynasty coffins in the collection of the San Diego Museum of Man. This article examines the nature of the wooden substrate, binder, pigments, and alteration products. The conservation needs of the collection are of special importance. The pigments used in the coffins are malachite, orpiment, carbon black, calcite, and red ocher. Gum Arabic was used as a binder. Wood anatomical studies identified fig as the wood. This article also covers the degradation product, oxammite, resulting from the microbiological decay of textile threads on a Hawk Mummy.

Recent work indicates that materials with nanoscale architectures, such as nanolayered Cu-Nb composites and nanoscale oxide dispersion-strengthened steels, are both thermally stable and offer improved performance under irradiation. Current understanding of the atomic-level response of such materials to radiation yields insights into how controlling composition, morphology, and interface-defect interactions may further enable atomic-scale design of radiation-tolerant nanostructured composite materials. With greater understanding of irradiation-assisted degradation mechanisms, this bottom-up design approach may pave the way for creating the extreme environment—tolerant structural materials needed to meet the world's clean energy demand by expanding use of advanced fission and future fusion power.

The method we introduced in 1992 for measuring hardness and elastic modulus by nanoindentation testing has been widely adopted and used in the characterization of mechanical behavior at small scales. Since its original development, the method has undergone numerous refinements and changes brought about by improvements to testing equipment and techniques, as well as advances in our understanding of the mechanics of elastic-plastic contact. In this article, we briefly review the history of the method, comment on its capabilities and limitations, and discuss some of the emerging areas in materials research where it has played, or promises to play, an important role.

Surface plasmon polaritons are responsible for various optical phenomena, including negative refraction, enhanced optical transmission, and nanoscale focusing. Although many materials support plasmons, the choice of metal for most applications has been based on traditional plasmonic materials, such as Ag and Au, because there have been no side-by-side comparisons of different materials on well-defined, nanostructured surfaces. This article will describe how a multiscale patterning approach based on soft interference lithography can be used to create plasmonic crystals with different unit cell shapes—circular holes or square pyramids—which can be used as a platform to screen for new materials. The dispersion diagrams of plasmonic crystals made from unconventional metals will be presented, and the implications of discovering new optical coupling mechanisms and protein-sensing substrates based on Pd will be described. Finally, the opportunities enabled by this plasmonic library to dial into specific resonances for any angle or material will be discussed.

The powerful lasers being constructed for inertially confined fusion generate enormous pressures extremely rapidly. These extraordinary machines both motivate the need and provide the means to study materials under extreme pressures and loading rates. In this frontier of materials science, an experiment may last for just 10s of nanoseconds. Processes familiar at ambient conditions, such as phase transformations and plastic flow, operate far from equilibrium and show significant kinetic effects. Here we describe recent developments in the science of metal deformation and phase transitions at extreme pressures and strain rates. Ramp loading techniques enable the study of solids at high pressures (100s of GPa) at moderate temperatures. Advanced diagnostics, such as in situ x-ray scattering, allow time-resolved material characterization in the short-lived high-pressure state, including crystal structure (phase), elastic compression, the size of microstructural features, and defect densities. Computer simulation, especially molecular dynamics, provides insight into the mechanisms of deformation and phase change.

Much of the interaction of a material with its environment is governed by its surface, and modulation of the material's surface characteristics can vastly broaden its range of application. This review focuses on the tailoring of surfaces of materials to achieve specific changes in their responses to external stimuli to enhance their prospects for applications in the biomedical field. Combining the inherent properties of different classes of materials such as polymers, metals, mesoporous materials, and magnetic nanoparticles with a responsive surface presents unique opportunities. Applications include surface-modified filters for the effective adsorption and separation of biomolecules, materials for the promotion of cell adhesion or detachment for cell sheet engineering and regenerative medicine, actuators, or valves, and vehicles for the controlled and targeted delivery of therapeutic agents. The commonly used external stimuli are heat, pH, and light, and these, as well as electrical stimulation used in conjunction with conducting polymers, will be addressed in this review. Progress in the field of responsive surfaces has been rapid, and continuing research can be expected to result in more innovative and exciting developments. Nevertheless, much work remains to be done to meet the challenges in the translation of these systems from the laboratory to clinical applications.