PhD defense: Éloé Dubus

Title

Investigation and application of DASA molecules : extension of photochromic properties, towards the solid state

Abstract

Donor Acceptor Stenhouse Adducts (DASA) represent a recent family of negative photochromic compounds that have gained significant interest over the past decade. The study of their rapid decoloration and recoloration kinetics has led to extensive studies in solution. However, their behavior in solid matrices, despite being essential for applications in the field of optically active materials, remains largely unexplored. In this context, this study aims to develop an initial methodology for investigating these compounds on solid substrates, particularly through their incorporation into a polymer matrix, to preserve their photochromic properties, or even surpass some of their current limitations. It also seeks to enhance the properties of DASA, whether in terms of initial coloration or wavelength activation range. To achieve this, an in-depth characterization of the DASA mechanism in solution was first conducted. Following the optimization of a preparation protocol in a polymer matrix, the focus shifted to achieving new shades through mixtures of photochromic compounds, as well as with non-photoreactive dyes. To enhance the performance of the samples, special attention was given to expanding their narrow spectral activation range. This was accomplished by introducing relays to exploit a Förster Resonance Energy Transfer (FRET) cascade effect, thereby extending their photoreactivity from the visible to the near-UV region. Finally, part of the study was dedicated to exploring alternatives to polymer matrices, such as micelles or laser photofragmentation.

PhD supervision

• Director: Dr. Rémi Métivier, Research Director, PPSM, CNRS
• Co-director: Dr. Guillaume Laurent, Research Assistant, PPSM, CNRS

Members of the jury

• Frédérique Loiseau, Professor, Université Grenoble-Alpes, Reviewer

• Fabien Salaün, Professor, Université de Lille, Reviewer

• Anne Lafosse, Professor, Université Paris-Saclay, Examiner

• Olivier Galangau, Research Assistant, Université de Rennes, Examiner

• Ryohei Yasukuni, Assistant Professor , Osaka Institute of Technology, Examiner

Invited

• Sarah Berhanu, Direction générale de l'Armement

• Rachid Jaoui, Agence de l'innovation Défense