Eur. Phys. J. E 8, 193-199 (2002)
DOI: 10.1140/epje/i2001-10074-x

The origins of fast segmental dynamics in 2 nm thin confined polymer films

E. Manias and V. Kuppa

Department of Materials Science & Engineering, The Pennsylvania State University, 325-D Steidle Building, University Park, PA 16802, USA

manias@psu.edu

(Received 9 August 2001 and Received in final form 7 January 2002)

Abstract
Molecular-Dynamics computer simulations were used to study 2 nm wide polystyrene films confined in slit pores, defined by inorganic crystalline surfaces. The simulated systems mimic experimentally studied hybrid materials, where polystyrene is intercalated between mica-type, atomically smooth, crystalline layers. A comparison between the experimental findings and the simulation results aims at revealing the molecular origins of the macroscopically observed behavior, and thus provide insight about polymers in severe/nanoscopic confinements, as well as polymers in the immediate vicinity of solid surfaces. Pronounced dynamic inhomogeneities are found across the 2 nm thin film, with fast relaxing moieties located in low local density regions throughout the film. The origins of this behavior are traced to the confinement-induced density inhomogeneities, which are stabilized over extended time scales by the solid surfaces.

PACS
83.10.Rs - Computer simulation of molecular and particle dynamics.
68.60.-p - Physical properties of thin films, nonelectronic.
81.07.Pr - Organic-inorganic hybrid nanostructures.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002