Regensburg 2002 – scientific programme
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SYPF: Struktur und Dynamik in dünnen Polymerfilmen
SYPF 2: Poster Session
SYPF 2.27: Poster
Thursday, March 14, 2002, 09:00–18:00, Poster B
Broadband Dielectric Spectroscopy on the molecular dynamics of (atactic) PMMA polymer brushes — •Anatoli Serghei1, Tim Stephan2, Manfred Schmidt2, and Friedrich Kremer1 — 1Institut für Experimentelle Physik, Linnéstrasse 5, 04103 Leipzig — 2Institut für Physikalische Chemie, Welderweg 11, 55099 Mainz
The molecular dynamics of thin PMMA macromonomer layers under the influence of confinement has been investigated by means of Broadband Dielectric Spectroscopy. The PMMA macromonomer is built up by a PMA backbone which has laterally attached atactic PMMA side chains (2800 g/mol), forming a cylindrical architecture (so-called polymer brush).
The dynamics of the PMMA macromonomer was compared with the dynamics of normal PMMA (consisting only of the side-chains of our macromonomer). For both samples the influence of restricted film geometry was investigated down to a thickness of ≈ 30 nm. The measurements were done in the frequency range from 0.1 Hz to 10 MHz and at temperatures from 280 K to 420 K.
Two relaxation processes have been observed: alpha relaxation (corresponding to the dynamic glass transition) and beta relaxation. While the dynamics of the beta relaxation is practically the same for both PMMA samples, we observe that the alpha relaxation for PMMA macromonomer is about 10 times slower than the one of normal PMMA. We attribute this result to different densities of macromonomer and normal PMMA.