ED Sciences Chimiques
Elaboration of self-healing poly(dimethylsiloxane) materials for space applications and development of silica-based nanocomposites
by Mickaël DU FRAYSSEIX (Laboratoire de Chimie des Polymères Organiques)
The defense will take place at h00 - Amphi 1 16 Av. Pey Berland ENSMAC 16, 33600 Pessac
in front of the jury composed of
- Stéphane CARLOTTI - Professeur - Bordeaux INP - Directeur de these
- Audrey LLEVOT - Maîtresse de conférences - Bordeaux INP - CoDirecteur de these
- Simon LEWANDOWSKI - Docteur - ONERA - Examinateur
- Sophie PERRAUD - Docteure - CNES - Examinateur
- Vincent LADMIRAL - Directeur de recherche - CNRS - Rapporteur
- Eric DANTRAS - Professeur - Université de Toulouse - Rapporteur
- Marc GUERRE - Chargé de recherche - CNRS - Examinateur
- Frédéric PERUCH - Directeur de recherche - CNRS - Examinateur
Poly(dimethylsiloxane) (PDMS) is widely used for space applications due to its transparency and its resistance to thermal and UV exposure. However, prolonged exposure of these materials to the space environment leads to yellowing and cracking, contributing to satellite degradation. In this context, PDMS with self-healing properties have been designed to limit their degradation in geostationary orbit. A first approach, based on the combination of urea and imine functions, enabled the formation of supramolecular networks and covalent adaptable networks (CANs). These systems led to a reduction in surface crack density after proton irradiation. However, the formulations showing the highest stability under proton exposure exhibit a low elastic modulus as well as limited thermomechanical properties above 80 °C. To overcome these limitations, CANs incorporating silyl ether functions were developed. This strategy significantly improved the mechanical and thermomechanical properties of the materials, while maintaining their stability under proton irradiation. Finally, a final approach involved the development of self-healing PDMS nanocomposites. These systems rely on the establishment of dynamic covalent bonds between the PDMS matrix and dispersed silica nanoparticles. These nanocomposites exhibit enhanced mechanical and thermomechanical properties, without compromising optical transparency. Proton irradiation tests also demonstrated improved stability of PDMS under space environment conditions.