Coordinative Ring-Opening Polymerization of Limonene Carbamate Toward Phosgene- and Isocyanate-Free Polyurethane.

This study presents a phosgene- and isocyanate-free route for the synthesis of polyurethanes using (R)-limonene as a bio-based starting material. The synthesis of the cyclic limonene-based carbamate monomer LU is achieved in high yields using dimethyl carbonate as a sustainable, less hazardous phosgene surrogate and is verified by NMR, SC-XRD, ESI-MS, GC-MS, and elemental analysis. Polymerizations were carried out by coordinative ring-opening polymerization.

Influence of Ligand Design and Non-Covalent Interactions on the Isoselective Ring-Opening Polymerization of rac-β-Butyrolactone Using Salan and Salalen Rare-Earth Metal Catalysts.

We herein report the influence of the ligand framework on the isoselective ring-opening polymerization (ROP) of rac-β-butyrolactone using highly active in situ generated salan [ONNO] and salalen [ONNO] rare-earth metal complexes. The stereochemistry was found to be highly dependent on the ortho-substituents, enabling the synthesis of either isotactic poly(3-hydroxybutyrate) (PHB) (up to P = 0.92) or syndiotactic PHB (up to P = 0.

Photo-Activity of Silacyclopropenes and their Application in Metal-Free Curing of Silicones.

Silicone elastomers are usually produced via addition or condensation curing by means of platinum- or tin-based catalysis. The employed catalysts remain in the final rubber and cannot be recovered, thus creating various economic and environmental challenges. Herein, a light-mediated curing method using multifunctional silacyclopropenes as crosslinker structures was introduced to create an effective alternative to the conventional industrial crosslinking.

CO activation through C-N, C-O and C-C bond formation.

A comparative model for the chemisorption of CO was explored via three representative reaction pathways: carboxylation of cyclohexanone, carbonation of cyclohexanol, and carbamation of cyclohexylamine. The model substrates were activated using 1,8-diazabicyclo[5.4.