Structure and Dynamics of Polymer-Layered Silicate Nanocomposites

摘要

The static and dynamic properties of polymer-layered silicate nanocomposites are discussed in the context of polymers in confined media. Despite the topological constraints imposed by the host lattice, mass transport of the polymer into the silicate layers (at least in the case of essentially non-polar polystyrene) appears to be unhindered and exhibits mobility similar to that of the pure polymer. However, both the local and global dynamics of the polymer in the hybrids are dramatically different from those in the bulk. On a local scale, intercalated polymer chains exhibit higher flexibility along their backbone along with a marked suppression (or even absence) of cooperative dynamics typically 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 altered and parallel those of other intrinsically anisotropic materials such as block copolymers and liquid crystals.