Polymer nanocomposites

Polymer nanocomposites (PNCs)-that is, nanoparticles (spheres, rods, plates) dispersed in a polymer matrix-have garnered substantial academic and industrial interest since their inception, circa 1990. This is due in large part to the incredible promise demonstrated by these early efforts: PNCs will not only expand the performance space of traditional filled polymers, but introduce completely new combinations of properties and thus enable new applications for plastics. Low volume additions (1-5%) of nanoparticles, such as layered silicates or carbon nanotubes, provide property enhancements with respect to the neat resin that are comparable to those achieved by conventional loadings (15-40%) of traditional fillers. The lower loadings facilitate processing and reduce component weight. Most important, though, is the unique value-added properties not normally possible with traditional fillers, such as reduced permeability, optical clarity, self-passivation, and increased resistance to oxidation and ablation. These characteristics have been transformed into numerous commercial successes, including automotive parts, coatings, and flame retardants. This issue of the MRS Bulletin provides a snapshot of these exemplary successes, future opportunities, and the critical scientific challenges still to be addressed for these nanoscale multiphase systems. In addition, these articles provide a perspective on the current status and future directions of polymer nanocomposite science and technology and their potential to move beyond additive concepts to designed materials and devices with prescribed nanoscale composition and morphology.