STRUCTURE AND DYNAMICS OF POLYMER-LAYERED SILICATE NANOCOMPOSITES

The static and dynamic properties of polymer-layered silicate nanocomp osites are discussed in the context of polymers in confined media. Des pite the topological constraints imposed by the host lattice, mass tra nsport of the polymer into the silicate layers (at least in the case o f essentially non-polar polystyrene) appears to be unhindered and exhi bits mobility similar to that of the pure polymer. However, both the l ocal and global dynamics of the polymer in the hybrids are dramaticall y different from those in the bulk. On a local scale, intercalated pol ymer chains exhibit higher flexibility along their backbone along with a marked suppression (or even absence of cooperative dynamics typical ly associated with the glass transition. On a global scale, relaxation of polymer chains either tethered to or in close proximity (<1 nm as in intercalated hybrids) to the host surface are dramatically alter ed and parallel those of other intrinsically anisotropic materials such as block copolymers and liquid crystals.