Comprehensive Study of Polymeric Materials in Ancient Paintings by a Multimodal Analysis
AAP 2021 : Projet doctoral
Axe thématique : 3 - Défis et recherche fondamentale
Porteur de projet : Alain Brunelle (LAMS)
Co-porteuse de projet : Michel Sablier (CRC)
Doctorante : Gauthier Rosé
Laboratoires : LAMS, CRC
Gauthier Rosé, doctorant
Originaire de Strasbourg, Gauthier valide un bac scientifique au lycée International des Pontonniers, en section anglaise à Strasbourg. Gauthier commence ses études supérieures par une classe préparatoire PCSI-PC* au lycée Kléber, à Strasbourg.
Dans l’école d’ingénieur chimiste de Strasbourg, Gauthier poursuit ses études en inégrant l’École européenne de Chimie, Polymères et Matériaux de Strasbourg (ECPM) où il se spécialisera en 2e année dans les « Sciences Analytiques ». Cet enseignement lui confère un savoir et une expérience globale dans les nombreuses techniques analytiques pouvant servir dans les différents domaines scientifiques. Il passera son stage de fin d’étude de 6 mois au Centre Hospitalier Universitaire (CHU) de Limoges dans le service de pharmaco-vigilance, en partenariat avec les entreprises Shimadzu et Trajan Scientific and Medical.
Le but de ce projet était de développer, optimiser et valider une méthode de quantification automatisée, sur un CLAM-2030 de Shimadzu, d’un immunosuppresseur à partir de goutte de sang séché (Dried Blood Spots).
Après plusieurs expériences enrichissantes dans le monde de la pharmacologie-toxicologie, Gauthier rejoint finalement le Laboratoire d’Archéologie Moléculaire et Structurale (LAMS) comme doctorant sur les matériaux de patrimoine, sous la co-direction du Dr. Alain Brunelle, et celle du Dr. Michel Sablier, du Centre de Recherche sur la Conservation des Collections,.
Le projet de recherche
Materials from cultural heritage contain organic substances, which have polymerized, which may have suffered from degradation over time, and which are difficult to analyze and understand. Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) imaging and pyrolysis comprehensive two-dimensional gas chromatography / mass spectrometry (Py-GCxGC/MS) are two methods which provide, the one a surface analysis at the sub-micrometric scale, but with some identification issues, and the other a complete analysis, but without location. Here we propose to develop a new multimodal analysis associating these two methods. This approach has never been carried out, and their complementarity will allow a better knowledge at the micrometric scale of these fascinating materials.
The thesis project will initially use the capabilities of Py-GCxGC/MS to “shed light” on TOF-SIMS analyses of heritage materials, which need the help of a powerful separation method. The strategy will lie firstly by the analysis of mock-up of paint materials or artificially aged ones. These model samples will be analyzed in part by Py-GCxGC/MS and by TOF-SIMS, to better understand the complexity of the mass spectra obtained in TOF-SIMS imaging. A particular effort will be made to identify resins and waxes.
The second phase of the thesis will focus on samples from paintings and painted objects of relatively low heritage value on which we will take large samples to combine the two techniques, before focusing at the end of the thesis on the analysis of old paintings, only in TOF-SIMS.
The combination of two methods will overcome a major bottleneck in TOF-SIMS imaging, by the precise knowledge of material composition provided by Py-GCxGC/MS. Beyond the context of cultural heritage, the development of this new method of material multimodal analysis will also be a valuable tool for the analysis of materials in a larger sense, in particular complex materials like mixtures between pigments and binders, between mineral and organic materials, and / or with a structure requiring localized analysis at a micron scale or less.
