Synthesis of silicone resins by upcycling of silicon oil waste Shamna Salahudeen, Helena Fehrmann, Esteban Mejía Leibniz Institute for Catalysis (LIKAT), Germany Since their discovery by E. G. Rochow in 1941, silicone resins have become one of the most important silicon- derived polymers, thanks to the weatherability, heat and moisture resistance, dielectric properties, etc. [1],[2] Silicone resins are commonly synthesized from expensive silane monomers derived from the highly energy- demanding Müller-Rochow process, [3] including halo-silanes and organo-silanes. [4] In this contribution, we describe the development of a new straightforward, cost-effective, and practical approach for the manufacture of highly crosslinked methyl silicone resins by upcycling readily available silicone oil waste (made of linear polydimethylsiloxane, PDMS). Treating waste silicone oil with readily available bases under reflux condition at 120 °C in DMSO/water mixtures produces solid silicone resin with high yields (up to 80 %). The obtained resins were thoroughly characterized by solid-state NMR and thermo-gravimetric analysis. Additionally, with the help of in situ NMR and EPR spectroscopy methods, we have proposed a reaction mechanism, which interestingly, features the intermediacy of radical species, in contrast with previous investigations, which are based on nucleophilic substitution. References 1. E.G. Rochow, W.F. Gilliam, Polymeric methyl silicon oxides, J. Am. Chem. Soc. 63 (1941) 798–800. 2. E.G. Rochow, Methyl Silicones and Related Products, US 2,258,218, 1941. 3. Brook, M.A. and Skov, A.L., Macromol. Rapid Commun., 42: 2100048,2021. 4. Constance Robeynsa , Loïc Picardb , François Ganachauda,Progress in Organic Coatings 125, 287–315, 2018.
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