Single polymer chains, intercalation

The doping process of a single isolated chain resembles that of semiconductors. Electron acceptors or electron donors change the electron population in the valence or in the conduction band or, vice versa, electrons or holes from the polymer bands ionize the doping molecules, which are intercalated between the chains. Chemically speaking, this process equals an oxidation or reduction of the chains. The redox character of the doping process is reflected even more clearly by the fact that electrochemical oxidation and... 

Nanoparticles exist in spherical, mbe and whisker, and plate-like shapes and at least one of the three dimensions is required to be on a nanometric scale. Nanostructures of layered clays are further categorized as intercalated, in which the polymer chains have penetrated between the clay layers in a well-ordered multilayer morphology, and exfoliated, in which the clay layers have dispersed along the matrix and have no organized slnictme [7]. Carbon nanombes also exhibit two nanostructmes single-walled nanotube and mnltiwalled nanotube, which is composed of several tubes within each other. 

The quantitative assessment of nanocomposite formation is quite a challenge. The terms generally used, such as tactoid (= microcomposites), intercalated, and exfoliated, are rather oversimplifying models for some typical characteristics of different morphologies. The intercalation of silicate structures by polymer chains, the delamination of sihcate layers, the mixing of the various compounds, and the distribution of particles or single layers in the matrix are mechanisms that are... 

Beyond this traditional class of polymer-filler composites, two types of nanocomposites can be obtained. Intercalated structures are formed when a single (or sometimes more) extended polymer chain is intercalated (sandwiched) between the silicate layers. The result is a well-ordered multilayer structure of alternating polymeric and inorganic layers. Exfoliated or delaminated structures are obtained when the silicates are completely and uniformly dispersed in the continuous polymer matrix. The delamination configuration is of particular interest because it maximizes the polymer-clay interactions, making the entire surface of the layers available for the polymer. This should lead to the most significant changes in mechanical and physical properties. A schematic of the types of possible structure formations in PC composites is depicted in Fig. 13.2. 

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