Polymer blending has been typically regarded as a mixing process rather than a structuring process so polymer blends and composites are not necessarily optimized with regard to structure, properties, and composition. In this article, a new smart blending technology is described whereby melt components and solid additives are more controllably organized into micrometer-scale and sub-micrometer-scale shapes and arrangements to improve properties or impart functionality to extruded plastics. Chaotic advection is an enabling recent subfield of fluid mechanics for smart blending. It provides a method to controllably stretch and fold melt domains and evolve a multilayered structure leading to derivative morphologies, or indirectly manipulate solid additives. Recent advances in fluid mechanics have thereby been implemented to reconsider how blending is done. A variety of structured plastic materials are producible with a single smart blending device with no device alterations. Several examples and their improved physical properties are shown or discussed. (c) 2006 Wiley Periodicals, Inc.