Dynamical heterogeneity in nanoconfined poly(styrene) chains

Fluids in nanoscopic confinements possess a variety of unusual properties, and in particular, remarkable dynamical heterogeneities which vary on lengt h scales as short as a fraction of a nanometer. While the surface forces ap paratus provides an experimental probe of macroscopic properties of fluids in contact with atomically smooth solid surfaces, few experimental probes a re available which test the microscopic origins of these heterogeneities. I n this article we describe our recent efforts to apply nuclear magnetic res onance spectroscopy to nanoscopically confined poly(styrene) (PS) created b y intercalation into a surface-modified fluorohectorite. A comparison betwe en surface-sensitive cross polarization experiments with spin-echo experime nts which probe the entire organic layer suggests that PS in the center of the nanopores is more mobile than the bulk at comparable temperatures, whil e chain segments which interact with the surface are dynamically inhibited. (C) 2000 American Institute of Physics. [S0021-9606(00)71206-2].