Synthesis of pseudoâtelechelic diols by transesterification and thiolâene coupling
2012
Desroches, Myriam | Caillol, Sylvain | Auvergne, Rémi | Boutevin, Bernard
Transesterification of methyl esters of rapeseed oil with ethylene glycol in excess led to a Ïâhydroxy fatty ester with a yield of 90%. 2âMercaptoethanol was grafted onto the double bonds of this Ïâhydroxy fatty ester by UV initiated thiolâene coupling under mild conditions. Double bond conversion was found to be quantitative and yielded a polyol with average of two primary hydroxyl functions. This pseudoâdiol was characterized by means of NMR spectroscopy, titration and mass spectroscopy (MS) and was used to synthesize polyurethane (PU) by step growth polyaddition with methylene diphenylâ4,4′âdiisocyanate. The polymer, analyzed by thermogravimetric analysis (TGA) and DSC, showed a glass transition temperature of −3°C, close to the one measured (8°C) on a PU based on a commercial polyol, Desmophen 1150. Practical application: The products of the chemistry described in this contribution, i.e. polyol from vegetable oils derivatives, provide biobased building blocks for further PUs syntheses by reaction with diisocyanates. The obtained PUs are partially biobased and may be applied as binders and coatings.
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