Silicones or polyorganosiloxanes (R1R2Si-O)n are polymers with outstanding chemical and physical properties valorized in everyday life in a wide range of industrial applications: construction, automotive, electronics, medicine, personal care etc [1]. As a result, the growth forecasts for these materials are substantial with a compound annual growth rate (CAGR) of 7.4% from 2021 to 2030 [2]. Nevertheless, harmonious economic development of silicones must also take up the challenge of the ecological transition by answering two important questions regarding i) the new regulatory requirements on materials purity, particularly in terms of organocyclosiloxane content, and ii) the end of life of polymeric silicone materials, by avoiding for example, strategies that do not reuse or recycle the material after its main use, in particular when thinking about crosslinked silicones [3]. Regarding the first point, the evaluation of new catalysts for the ring-opening polymerization of organocyclosiloxane will be presented. In particular, the efficiency of specific Brönsted acid ionic liquids (BAIL) and other naturally-derived molecules in the design of linear poly(dimethyl siloxane)s with controlled molar masses and functionality will be discussed, with an emphasis on the residual amount of cyclic byproducts [4]. To address the second point, the preparation of physically crosslinked silicone-based materials with enhanced properties will be discussed; various chemical strategies such as ‘ionic vulcanization’ via the addition of natural molecules [5], or supramolecular zwitterionic silicones [6]. For that purpose, the potential of the aza-Michael reaction will in particular be emphasized, as a simple and accessible addition reaction that allow designing polymers with specific functionalities and topologies thanks to the wide range of Michael acceptors and Michael donors, as well as the operation conditions in which the reaction is carried out [7].

References 1. T. Köhler, A. Gutacker, E. Mejía Org. Chem. Front 2020, 7, 4108. 2. https://www.globenewswire.com/en/news-release/2022/10/12/2532848/0/en/Global-Silicone-Market-Size-to-grow-USD-30-9-Billion-by-2030 [25 April 2023]. 3. A. T. Wolf, A. Stammer Polymers, 2024, 16, 2220. 4. W. Nzahou Ottou, A. Boulègue Mondière, H. Parisot, D. Blanc, D. Portinha, E. Fleury Polymer Chem, 2023, 14, 4693. 5. E. Fleury, F. Ganachaud, D. Portinha, G. Duaux, A. Genest, E. Pouget Silicones Materials, Elkem patent, WO 2019/166507 6. A. Genest, D. Portinha, E. Pouget, K. Lamnawar, F. Ganachaud, E. Fleury Macromol. Rapid Commun. 2021, 42, 2000372. 7. M. Ben Belaiche, F. Ganachaud, E. Fleury, D. Portinha, in preparation.

Acknowledgments

All the authors acknowledge financial support from Elkem Silicones and ANR (Arcade, Siliscy, Sil-Gen- projects).