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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: Poster II
CPP 21.8: Poster
Dienstag, 19. März 2024, 18:00–20:00, Poster E
Mechanism for the formation of millimeter-long solid filaments by spin coating dilute solutions of a crystallizable polymer — •Da Huang1, Thorsten Hugel2, and Günter Reiter1 — 1Institute of Physics, University of Freiburg, Freiburg, Germany — 2Institute of Physical Chemistry, Albert-Ludwigs-Universität Freiburg, Germany
We investigated the formation of millimeter-long filaments formed by spin-coating dilute para-xylene solutions of rapidly crystallizable polyethylene chains with a contour length in the micrometer range onto mica substrates at high temperatures. These filaments were radially oriented and accumulated at the periphery of the substrate. Our observations can be explained by the stretching of polymers through the flow field induced by spinning the solution on a solid substrate. The corresponding loss in conformational entropy emphasized attractive interactions between polymers, which resulted in the formation of bundles and their assembly into long filaments. Caused by a Plateau-Rayleigh-type instability of a liquid coating on a solid filament and due to crystallization, these filaments were decorated with various small-scale structures. Still in solution, the resulting filaments experienced a Coriolis force as they were dragged towards the periphery of the sample, causing a deviation of their orientation from the radial direction. Finally, filaments adsorbed on the substrate, the solvent evaporated completely and the resulting variety of crystalline patterns and morphologies were examined by various microscopy techniques.
Keywords: coil-stretch transition; dilute polymer solution; intermolecular interactions; phase separation; flow induced crystallization