Confocal Microscopy Visualizes Particle–Crack Interactions in Epoxy Composites with Optical Force Probe-Cross-Linked Rubber Particles

Macromolecules, vol. 55, pp. 1060–1066

Abstract

Brittle fracture often compromises the durability of glassy polymers. This can be mitigated by reinforcing the matrix with a filler, activating a range of toughening mechanisms. Therefore, it is desirable to better understand the mechanical response of polymer composites, but a direct visualization of the mechanical fate of second-phase inclusions upon material fracture was previously unavailable. Here, rubbery poly(hexyl acrylate) particles, cross-linked with an optical force probe (OFP), are dispersed within an epoxy matrix, the material is fractured, and particle–crack interactions are visualized with confocal laser scanning microscopy. The dual-fluorescence character of the OFPs allows the differentiation between particles that remain intact and those that are stressed beyond bond scission upon interaction with a propagating crack. The localized activation of OFPs reveals stress gradients within the particles and crack direction pathways, hence providing a new layer of information over fracture events in polymer composites.

Authors 3

1. Maria Stratigaki Aachen DWI - Leibniz Institute for Interactive Materials

   DWI – Leibniz Institute for Interactive Materials

   Affiliation as printed

   DWI─Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany

2. Christoph Baumann Aachen DWI - Leibniz Institute for Interactive Materials Institute of Technical and Macromolecular Chemistry

   RWTH Aachen University · DWI – Leibniz Institute for Interactive Materials

   Affiliation as printed

   DWI─Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany

   Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany

3. Robert Göstl corresponding Aachen DWI - Leibniz Institute for Interactive Materials

   DWI – Leibniz Institute for Interactive Materials

   Affiliation as printed

   DWI─Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany