Regensburg 2022 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 8: Focus Session: Photonic Structures from Polymer and Colloidal Self-Assembly
CPP 8.5: Hauptvortrag
Montag, 5. September 2022, 16:45–17:15, H38
Hierarchically structured mechanochromic deformation-sensing pigments — •Jessica Clough1, Cédric Kilchoer1, Bodo Wilts1,2, and Chris Weder1 — 1Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, Fribourg 1700, Switzerland — 2Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Str. 2a, 5020 Salzburg, Austria.
Mechanochromic materials can change their colour in response to mechanical force and are useful for fundamental studies as well as practical applications. A versatile platform with extended sensing capabilities would be valuable for monitoring complex mechanical behaviours and failure events. Here, we report that this is possible by combining photonic structures, which alter their reflection upon deformation, and covalent mechanophores, whose absorption changes upon mechanically induced bond scission, in hierarchically structured assemblies. This was achieved by synthesising microspheres of an elastic polymer with spiropyran-based cross-links and incorporating non-close-packed silica nanoparticles into this matrix. The shift of the reflection band produced by the silica is noticeable at less than 1% strain, while the conversion of the spiropyran can require strains exceeding 50%. The two responses can be tailored via the silica content and the cross-link density. The mechano-sensing pigments can readily be incorporated into different materials of interest and probe local deformations from within. This was demonstrated by monitoring high-strain deformation of poly(dimethyl siloxane) in compression and local strain field variations caused by the necking of semicrystalline polyethylene.