ISBN 978-3-8439-3859-4

978-3-8439-3859-4, Reihe Mikrosystemtechnik

Matthias Menzel
Nanostructured Polymer Brushes - A Study of their Morphology and Stability

204 Seiten, Dissertation Albert-Ludwigs-Universität Freiburg im Breisgau (2018), Softcover, B5

Zusammenfassung / Abstract

Polymer brushes are surface attached polymer layers consisting of densely end-grafted polymer chains. Besides the unique properties of the different polymer brushes, it has become more and more important to locally control those properties by patterning of the brushes. In particular, nanopatterned brushes (NPBs) have proven to show extraordinary characteristics. The NPBs have pattern sizes comparable to their molecular size or rather the contour length of the surface attached chains and show unique properties at the nanoscale. When moving from microstructured brushes (where the pattern size is small, but still large compared to molecular dimensions) to their nanostructured peers, important changes occur in the physics of the system. For both micro- and nanostructured brushes, the chains located at the edge of the pattern can fan out into areas where no surface-bound molecules are present. In this way the lateral pressure on each polymer chain is reduced and the chains are less stretched. However, they cannot reach too far out into the free area nearby as they are still bound to the surface with one end. For microstructured brushes such effects only have an impact on a small portion of chains, namely those close to the edge of the pattern. Upon decreasing the dimension of the patterns the relative proportion of such chains compared to the total number of chains contained in the patterned layer increases. When the pattern sizes reach the contour length of the surface-bound polymer chains, a transition occurs from a 2D system (microbrush regime), which can swell only in one dimension, to a 3D system (nanobrush regime), which can practically swell in all three dimensions. This gives rise to a scaling behavior, where the brush height is directly correlated with the pattern size. Hence, the unique structural properties of NPBs have a strong influence on the thermodynamic stability.