Dresden 2026 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster I

CPP 17.43: Poster

Montag, 9. März 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