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Silicones are ubiquitous materials owing to their exceptional mechanical and thermal stability as well as low toxicity. Recycling them has become a relevant target for circular economy purposes. Conventional processes of chemically recycling polysiloxanes allow for the recovery of valuable cyclic monomers. Unfortunately, they lack efficiency and still require high operating temperatures, thus yielding detrimental by-products. Herein, we introduce an efficient method for the solvent-free depolymerisation of linear polydimethylsiloxanes using a [polydentate ligand–potassium silanolate] complex as a catalyst that promotes the chemical recycling of silicones into cyclic monomers from many industrial substrates including actual waste materials. Our method only requires a small amount of catalyst (0.1 mol%) and proceeds over a wide range of temperatures (60 °C–170 °C) to efficiently yield a mixture of cyclosiloxanes (up to 98–99% yield) from up to a 100 g scale of waste silicone oils. Moreover, the recyclability of this catalyst was demonstrated over five runs without loss of activity. [ABSTRACT FROM AUTHOR]

A range of thermomorphic polyethylene‐supported organocatalysts is prepared from N‐alkyl imidazoles and polyethylene iodide (PEI) with good yields (85–92%) and high funtionality (98–99%). The catalytic activity of these species is studied for the ring opening of epoxidized methyl oleate with CO2 to give the corresponding cyclic carbonate. The reaction is carried out at 100 °C to fully exploit the thermomorphic behavior of the organocatalysts. The optimized conditions (neat, 100 °C, and 20 bar of CO2) are applied to a range of epoxidized fatty acids, including an epoxidized rapeseed oil, to give the corresponding carbonates with good yields (75–96%). The catalyst recycling is also studied, and no significant loss of activity is observed after ten runs. The fatty carbonates are important intermediates for the preparation of non‐isocyanate polyurethanes (NIPUs). [ABSTRACT FROM AUTHOR]

An imidazolium catalyst supported on thermomorphic polyethylene (PE) was prepared from 1‐methylimidazole and polyethylene iodide (PE−I). The catalyst was characterized by 1H and 13C NMR, SEC and MALDI‐ToF mass spectrometry. Its catalytic activity was evaluated in the ring‐opening of epoxides with carbon dioxide to give cyclic carbonates under solvent‐free conditions. The catalyst proved to be active at low catalyst loading (down to 0.1 mol%) and allows the reaction to occur at low CO2 pressure (1–5 bar) and moderate temperature (100 °C). A range of terminal and internal epoxides was converted to the corresponding cyclic carbonates with high yields and selectivities. The recyclability of the catalyst was studied and no significant loss of activity was observed after 5 runs. [ABSTRACT FROM AUTHOR]

Lipidic polyols based on α‐hydroxyketone reactive groups were investigated for polyurethane thermosets. The reactivity of this peculiar secondary alcohol group in triacylglycerol structure was compared, without use of catalyst, to that of poly(1,2‐diol) triacylglycerol and castor oil to demonstrate the influence of ketone in the α position of the alcohol group in the presence of HDI for the urethanization rate. The kinetic effect of the ketone group was also studied on various lipidic architectures: mono(α‐hydroxyketone) ester, di(α‐hydroxyketone) diester and tri(α‐hydroxyketone) triacylglycerol. The presence of hydrogen bonds in the network coming from urethane, residual alcohol, and ketone in hard segments of PU was discussed and correlated with the thermal stability and the soft mechanical properties of the resulting polyurethane thermosets. [ABSTRACT FROM AUTHOR]

A series of thiazolium salts was prepared and tested for the cleavage of the α-hydroxyketone derived from methyl oleate. The robustness of these precatalysts was determined by dynamic thermogravimetric analyses (TGA). It has been shown that the stability of these species is mainly governed by the nature of the counter-anion and some of them were found to be stable until 350-400 °C. The α-hydroxyketone derived from methyl oleate was cleaved under reactive distillation conditions using optimized, thermally robust N-butylthiazolium triflate to give the cleavage product, namely, nonanal and methyl azelaaldehydate, with 85 and 70 % yields. A range of α-hydroxyketones derived from several fatty acids was cleaved to give the corresponding bio-based aldehydes with up to 98 % isolated yields. Finally, this protocol was successfully applied to a high-oleic sunflower oil derivative., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)