Myriam Desroches

From Vegetable Oils to Polyurethanes: Synthetic Routes to Polyols and Main Industrial Products

Most of biobased polyols for polyurethanes are synthesized from vegetable oils. In the first part, the present review goes into details of these different synthetic routes to obtain polyols. First, olefinic functionalities of triglycerides could easily be epoxidized, leading to reactive epoxide groups. Second, triglycerides double bonds could undergo a wide ranges of reactions to yield polyols. Finally, the carbonyl group could also be used as a reactive group to yield various polyols. In the second part, the present review is dedicated to the commercial biobased polyols, and, based on the patent literature focuses on the industrial synthetic routes.

Synthesis of glycerin carbonate-based intermediates using thiol–ene chemistry and isocyanate free polyhydroxyurethanes therefrom

A new synthesis of 4-[(prop-2-en-1-yloxy)methyl]-1,3-dioxolan-2-one (AGC) was performed by Williamson ether synthesis from 4-(hydroxymethyl)-1,3-dioxolan-2-one. Dicyclocarbonates were synthesized by UV thiol–ene coupling of allyl-cyclocarbonate with a 2,2′-oxydiethanethiol. This photochemical thiol–ene reaction was carried out under air, with neither solvent nor photoinitiator. The products, obtained with high yield, were characterized by 1H NMR and FTIR analysis. The synthesized dicyclocarbonates were used without purification to synthesize polyhydroxyurethanes without isocyanate by step growth polyaddition with 1,10-diaminodecane. The synthesized polyhydroxyurethanes were characterized by 1H NMR, FTIR, ATG and DSC analysis. These polyhydroxyurethanes exhibited glass transition temperatures from −31 °C to −14 °C, molecular weight from 7,000 g mol−1 to 9000 g mol−1 and degradation temperature for 5% of weight loss (Td 5%) between 227 °C and 250 °C.

Biobased cross-linked polyurethanes obtained from ester/amide pseudo-diols of fatty acid derivatives synthesized by thiol–ene coupling

Ester-containing pseudo-telechelic diols of fatty acid derivatives were synthesized via a two-step reaction (transesterification with diol compounds followed by thiol–ene radical coupling), and amide-containing pseudo-telechelic diols of fatty acid derivatives were also synthesized in a similar way, i.e. amidification reaction followed by thiol–ene radical coupling. A wide range of both ester- and amide-containing pseudo-telechelic diols were thus obtained by varying the spacer length between either ester or amide functions. These compounds were thoroughly characterized by means of NMR analysis and by titration. Their viscosity as well as their thermal behavior was assessed. Polyurethanes (PUs) were then obtained by reaction with a commercially available diisocyanate (MDI prepolymer). It was shown that thermostability of PUs was higher when using ester-containing pseudo-telechelic diols. In contrast, the amide groups increase the glass transition temperature of PUs through hydrogen bonding and also accelerate the network formation by acting as catalyst. Finally we showed that the higher the chain length in between functional groups the higher the softness of the PUs.