Molecular dynamics study of the intercalation of diblock copolymers into layered silicates

Polymer-layered silicate nanocomposites may be formed by annealing layered silicate particles with a polymer melt. Polymer molecules flow from a bulk melt into the galleries between silicate sheets, swelling the silicate stru cture. The use of an amphiphilic intercalant raises possibilities of formin g novel structures and enhancing the intercalation kinetics relative to the case of homopolymer intercalants. We perform molecular dynamics simulation s of the flow of a symmetric diblock copolymer from a bulk melt into a slit whose surfaces are modified by grafted surfactant chains, and whose walls are maintained at a constant pressure to permit the slit to open as polymer intercalates. Intercalation kinetics are examined for a variety of polymer -surface and interblock interactions and for thermodynamic states in which the bulk polymer occupies either a lamellar or disordered phase. Comparison to previous simulations of homopolymer intercalation demonstrates that dib lock copolymers may be used to intercalate a block that would not spontaneo usly intercalate as a homopolymer. (C) 2000 American Institute of Physics. [S0021-9606(00)50120-2].