Novel materials.

Materials have central roles in all fields of engineering; they define, through structures and devices, our interfaces to the physical and the virtual world. The emergence of new materials catalyzes transformative advances in civilizations, to an extent that eras of human development are often defined by the prevailing materials used in engineered systems, from the Stone, Bronze, and Iron Ages to the present times, aptly referred to as the Silicon or the Polymer Age. From an academic standpoint, the fundamental phenomena that define complex relationships between chemical compositions, structures, and properties in advanced materials serve as the basis for some of the most intellectually stimulating and dynamic areas of research in the physical sciences. This work has additional appeal because it is intrinsically interdisciplinary and combines essential aspects of traditional fields of study in physics, chemistry, and even biology, to an increasing extent, together with engineering processes and control strategies. Progress in materials science and in the engineering application of new materials is essential to the pursuit of solutions to societal grand challenges. Examples span those related to the development of sustainable sources of energy, from high-power magnets for wind turbines to designer semiconductors for solar cells; to the invention of technologies that improve human health, from metal alloys for lightweight prosthetics to polymer matrices for controlled drug release; to progress in intraand interplanetary travel within realms of objective and virtual reality alike, from high-efficiency batteries for emissions-free vehicles, to carbon composites for fuel-efficient spacecraft, to atomically thin films for high-speed integrated circuits. This Special Feature on Novel Materials presents a collection of perspectives articles, short reviews, and original research papers designed to capture some of the breadth and excitement in recentmaterials research. This representative set of topics intersects critical areas in electronics, biology, advanced manufacturing, and chemical synthesis, with interdisciplinary foci that combine scientific discovery with engineering applications. The issue begins with three articles on materials for classes of biomedical devices that offer capabilities with direct benefits in human health. The first article, by Ailianou et al. (1), describes fundamental studies of biodegradable polymers used in advanced vascular scaffolds designed for the treatment of coronary heart disease. These devices, known as stents, deploy into blood vessels where they provide structural reinforcement following procedures to remove obstructive plaques. Traditional metal stents, used on more than a half-million patients annually, remain in the body, where they present lifelong risks, most significantly because of their tendency to nucleate the formation of blood clots. Biodegradable polymers provide an alternative, in the form of stents that dissolve and disappear gradually after their function is no longer needed, thereby eliminating unnecessary device load on the patient. Such types of stents are rapidly replacing conventional counterparts. The findings reported in the Ailianou et al. article provide important insights into the morphological characteristics of the constituent polymers that confer the mechanical strength necessary for these and related applications. In particular, the authors discover that deformations caused by deployment of these stents align the polymer chains in a manner that increases their strength and prevents the formation of fractures. Such understanding has important practical implications for the engineering design of ultrathin, low-profile devices. The second article focuses on materials designed to prevent the formation of clots and biofilms on the surfaces of stents and other implants. Specifically, Sunny et al. (2) introduce a composite coating that consists of a porous solid matrix filled with a liquid, to yield a repellent surface that prevents fouling. This system, as demonstrated in transparent coatings on endoscopes through a comprehensive set of animal trials, involves a design inspired by the slippery surfaces of the carnivorous pitcher plant, in which the liquid-infused material spontaneously forms a biocompatible, lubricating, “nonstick” overlayer. For endoscopes, the result is significantly enhanced antibacterial