Description du sujet de thèse

Recycling of Halogenated Polymers using Earth Abundant Metal Catalysts:

Halogenated polymers are omnipresent in our life from the construction sector to high-tech applications such as photovoltaic panels.[1] However, these materials release corrosive and toxic molecules (HCl, HF, COF2 etc.) upon heating, which limits the options available for their post-consumer waste management such as secondary recycling or incineration for energy recovery. Moreover, fluorinated polymers belong to the class of perfluoroalkyl and polyfluoroalkyl substances (PFAS), also known as "Forever Pollutants", and as such represent a major threat, both for the environment and public health.[2] In this general context, catalytic dehalogenation of these products using mild hydrogen donors (e.g. silanes) holds considerable promise, but very few efficient systems have been reported so far, and most of them use precious metals (Rh, Ir, Pt).[3] To overcome these limitations, within the frame of an ANR project we propose to synthetize highly electrophilic catalysts based on Earth-abundant group 4 metals (Ti and Zr) supported by strongly donating N-heterocyclic carbene (NHC) and phosphonium ylide (R3P+−CR2− <-> R3P=CR2) ligands.[4] The target catalysts will be evaluated for the dehalogenation of polymers and PFAS molecules in collaboration with our colleagues from the Institute of Molecular Chemistry of the University of Burgundy (Dijon). The resulting dehalogenated polymer products obtained will be then characterized in the Organic Polymer Chemistry Laboratory (Bordeaux) by a wide range of techniques in order to establish correlations between catalyst structure and activity.

Desired profile: The motivated candidate, holding a research master's degree or an engineering degree in molecular chemistry, interested in organic synthesis, coordination chemistry and catalysis, must demonstrate excellent teamwork skills and a good level of English. The thesis is scheduled to start on October 1, 2025. The required documents include a motivation letter and a detailed CV with ranking and grades from L3, M1 and M2, or transcripts from the three years of engineering school as well as names of at least one academic reference.

References:
[1] M. Gilbert, S. Patrick, Chapter 13 - Poly(Vinyl Chloride). In Brydson's Plastics Materials (8th Edition), Gilbert, M., Ed. Butterworth-Heinemann: 2017; pp 329.
[2] R. C. Buck, J. Franklin, U. Berger, J. M. Conder, I. T. Cousins, P. de Voogt, A. A. Jensen, K. Kannan,
S. A. Mabury, S. P. J. van Leeuwen, Integr. Environ. Assess. Manag. 2011, 7, 513.
[3] a) L. Monsigny, J. C. Berthet, T. Cantat, ACS Sust. Chem. Eng. 2018, 6, 10481. b) N. G. Bush, M. K. Assefa, S. Bac, S. M. Sharada, M. E. Fieser, Mater. Horiz. 2023, 10, 2047.
[4] a) D. A. Valyaev, Y. Canac, Dalton Trans. 2021, 50, 16434. b) M. El Kadiri, A. Cherradi, O. A. Filippov, C. Duhayon, V. César, E. S. Shubina, M. Lahcini, D. A. Valyaev, Y. Canac, Chem. Commun. 2025, 61, 2778.

Contexte de travail

The "Pre-Catalyst Engineering" research team, located at the CNRS Coordination Chemistry Laboratory (LCC), focuses on molecular organometallic chemistry and catalysis, with the aim of addressing current issues and challenges such as sustainable development, energy, and the environment.
The team's expertise is diverse and ranges from the design of original ligands and new concepts in coordination chemistry to the development of innovative catalytic processes.
The team also has extensive expertise in carbene and phosphorus ligands and in the chemistry of abundant non-noble metals.

Contraintes et risques

No particular risks.