Postdoctoral position (M/F) in Analytical Chemitry : Novel Analytical Approaches for the Study of Paint Layers

Job Description

Missions

Paints are composed of pigment particles dispersed in an organic fluid, called the binder. In the case of oil painting, the binders, composed of oil, harden through auto-oxidation to form a polymer network that ensures the cohesion and stability of the paint film. However, this network is susceptible to degradation under the influence of numerous factors, and the molecular mechanisms responsible for this alteration remain poorly understood. Notably, 19th-century paintings frequently exhibit significant degradation, sometimes attributed to the use of lake pigments (organic colorants fixed on mineral substrates), which may promote hydrolysis, acidification of the medium, and the formation of soft or poorly dried films. Nevertheless, these hypotheses are primarily based on empirical observations and case studies; the actual influence of lake pigments on the degradation of oil binders has not yet been systematically demonstrated, which constitutes a major issue for the understanding and conservation of these works.

The objective of this work is thus to develop novel analytical methodologies based on recent advances in separation techniques, mass spectrometry, and data processing to relate the physicochemical properties of oil paintings to their molecular description. In this context, the project will investigate ageing, drying, and degradation reactions in oil-based paint layers containing lake pigments. This research will analyze the influence of the nature of additives (notably the presence of lead driers) and variations in the preparation methods of lake pigments on these processes.

Activity

- Preparation and artificial ageing of model oil/lake pigment samples
- Development of tailored analytical methods: separation techniques (HPLC, SFC) coupled with mass spectrometry, multimodal imaging (MALDI, TOF-SIMS, AFM-IR)
- Development of data processing methods (molecular networks, image fusion algorithms, etc.)
- Analysis of model samples, historical paint test panels (prepared by a conservator-restorer), and potentially samples from artworks

Your Profil

Skills

PhD in Analytical Chemistry, with strong expertise in separation techniques and mass spectrometry (coupled with chromatography and/or imaging) and an interest in data processing.

Your Work Environment

The research will be conducted at the Laboratory of Molecular and Structural Archaeology (LAMS), under the supervision of Lucie Arberet and Laurence de Viguerie, and at the Molecular Chemistry Laboratory (LCM), under the supervision of David Touboul.

The LAMS is a Joint Research Unit (UMR 8220, Sorbonne Université and CNRS) that focuses on the role of materials and techniques in the creation of heritage objects. To address these issues, the laboratory has a physicochemical analysis platform comprising about ten instruments (XRF, FTIR, XRD, hyperspectral imaging, relaxometry, etc.), most of which enable non-invasive and in situ analyses. Liquid chromatography and a TOF-SIMS mass spectrometer complement the analytical equipment. The laboratory benefits from the environment of Sorbonne Université's specialized analytical platforms, such as the MS³U mass spectrometry platform. The team also has expertise in understanding material alteration phenomena through a set of artificial ageing chambers simulating different environments.
Address: LAMS – Sorbonne Université, 4 place Jussieu, 75005 Paris

The LCM is a Joint Research Unit (UMR 9168, École Polytechnique and CNRS). Its research, covering both fundamental and applied aspects, spans a wide spectrum of molecular chemistry, from organometallic chemistry to physical chemistry and analytical chemistry. The laboratory has state-of-the-art analytical chemistry equipment (MALDI-FT-ICR, part of INFRANALYTICS, LC and SFC coupling with timsTOF and ExcedIon Pro, latest-generation GC-MS/MS) that enables it to investigate numerous issues related to the analysis of complex samples present in trace amounts. These methods allow for both surface analysis and analysis after differential extraction of dissolved sample constituents.
Adress: LCM – Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex

Compensation and benefits

Compensation

€3,081.33 to €3,519.85 (gross monthly) for less than 2 years of experience (based on the current pay scales)

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

The research professions