Molecular dynamics in thin grafted and spin-coated polymer layers
Faculty of Physics, University of Leipzig, Linnéstr. 5, D-04103, Leipzig, Germany
2 Laboratoire de Physique de la Matiére Condensée, Collége de France, 11 Place Marcelin Berthelot, 75231, Paris Cedex 05, France
Broadband Dielectric Spectroscopy is employed to study the molecular dynamics in thin layers of grafted and spin-coated polydimethylsiloxane (PDMS) and of the type-A polymer cis-1,4-polyisoprene (PI). Strong resemblance with low-molecular-weight systems is found but additionally the conformation of the chain and its extension becomes important. For PI a confinement-induced relaxation is found. It is observable if the layer thickness is comparable to the end-to-end vector of the chain and it depends strongly on the separation between interfaces. In contrast, the dynamic (and hence the calorimetric) glass transition is not affected by the geometrical confinement.
© EDP Sciences, Società Italiana di Fisica, and Springer-Verlag, 2003