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

Abstract

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.