A broad range of scientific and technological problems involves multi-scales and complex systems. This paper reviews some of unique and interesting nano-scale phenomena and applications relevant to polymer processing. It addresses four subjects. The first one is concerned with the dynamics of polymer chains in confined geometries. In contrary to intuition one may have, polymer chains may diffuse much faster in confined geometries than in the bulk. The second subject deals with extruder processing of polymer nanocomposites. Understanding of the dynamics of polymer chains in confined geometries helps shade light on how nanoparticles may be dispersed in polymer matrices in a nanometer scale. The third one is on the use of nano-objects as nano-reactors. An example is given to show how one may take the advantage of nano-reactors to improve reaction yield and/or reaction selectivity. The last subject deals with reaction kinetics at polymer-polymer interfaces of a few nanometers in thickness, a very important issue in reactive polymer blending processes. (c) 2007 Elsevier Ltd. All rights reserved.