Dresden 2026 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 17: Poster I
CPP 17.43: Poster
Monday, March 9, 2026, 19:00–21:00, P5
Probing the Distribution of Residual Stresses in Thin Polymer Films Using Mechanochromic Molecular Springs — •Meirui Fu1, Raphael Hertel2, Bence Dajka3, Michael Walter3, Michael Sommer2, and Günter Reiter1 — 1Institute of Physics, University of Freiburg, Germany — 2Institute for Chemistry, Chemnitz University of Technology, Germany — 3FIT Freiburg, University of Freiburg, Germany
Polymer thin films prepared rapidly from solution by spin coating often retain residual stresses originating on a molecular level. However, typically these stresses are probed on a macroscopic level, yielding spatially averaged responses, but do not resolve forces acting on individual chains. Here, we employed mechanochromophores, covalently integrated along the backbone of a glassy polymer, as optical reporters whose emission response varies continuously with the applied force. By combining optical microscopy and spectroscopy, we were able to measure the sum of the forces acting on individual chains with high spatial resolution. In particular, we investigated the distribution of forces acting on non-equilibrated polymer chains. Samples prepared under different spin coating conditions exhibited systematic variations in the emission spectra, which reflect differences in the distribution of the sum of forces acting on individual chains. We distinguish contributions from polymers experiencing low and high forces, respectively, which exhibited opposite trends with preparation conditions. We tentatively relate the heterogeneity of the acting forces to differences in conformation of the non-equilibrated polymer chains.
Keywords: spin coating; residual stresses; mechanochromophores; force distribution; polymer