Synthesis of new polyurethanes from vegetable oil by thiol-ene coupling

Abstract

Soybean vegetable oil was functionalized in a single step by addition of mercaptan with hydroxyl functions by thermal thiol-ene coupling. The synthesized biobased polyol was analyzed by nuclear magnetic resonance, titrations, size exclusion chromatography, and mass analyses to precisely determine its average functionality, thus allowing the use of the mixture of products without purification. This polyol was added to a prepolymer of 4, 4’-diisocyanate diphenylmethylene (MDI) with a ratio OH/NCO of 1, to synthesize partially bio-based polyurethane by step growth polymerization. The synthesized polyurethane was compared to polyurethane obtained from a commercial polyether polyol polyester, named desmophen 1150. Mixtures of these polyols were made to optimize the properties of the materials obtained. Polymerization was monitored by rheology. Polyurethanes were characterized by thermogravimetric analysis, differential scanning calorimetry, shore hardness, and tensile tests at different temperatures to determine their thermal and mechanical properties. Different materials present the characteristics of soft and ductile elastomers with thermal stability of polyurethanes.