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CPP: Chemische Physik und Polymerphysik
CPP 1: Special Symposium: Molecular Dynamics in Confined Geometries
CPP 1.8: Fachvortrag
Monday, April 2, 2001, 17:45–18:15, 3010
Polymers in confining geometries: From isolated chains to (ultra-)thin polymer layers. — •Friedrich Kremer1, Lutz Hartmann1, Andreas Huwe1, Thomas Kratzmüller2, Hans-Georg Braun2, Annett Gräser3, and Stefan Spange3 — 1University of Leipzig — 2Institute for polymer research Dresden — 3University of Technology Chemnitz
The molecular dynamics of confined (low molar and polymeric) systems is determined by the counterbalance between surface- and confinement-effects: Due to interactions with the (inner) surfaces (e.g. the formation of H-bonds, grafting, physisorption) the molecular dynamics is slowed down, resulting in an increase in the glass transition temperature of the system. In contrast the confinement may induce an increase in "free volume" thus making the molecular dynamics faster than in the bulk system. This causes a decrease in the glasstransition temperature. This conterbalance will be exemplified in the talk by employing broadband dielectric spectroscopy (10−2 Hz - 109 Hz) to study the molecular dynamics of low molecular weight systems (ethyleneglycol, salol, etc.) [1,2] and polymers (polyethers) being contained in mesoporous systems (MCM-48, pore-diameter 2.5 nm; MCM-41, pore-diameter: 3.6 nm). Furthermore dielectric measurements of (grafted) polymers in (ultra-)thin layers will be studied [3].
[1] A. Huwe et al. Phys. Rev. Lett. 82, 2338 (1999).
[2] F. Kremer et al. J. Phys. Condens. Matter 11, A175 (1999).
[3] L. Hartmann et al. Macromol. Rapid Commun. 21, 814 (2000).