Difuranic Diols for Renewable Polymers with Pendent Furan Rings

Organocatalyzed cross-coupling of biomass platform chemicals furfural and 5-hydroxymethylfurfual has been utilized to prepare a pair of constitutional isomers of difuranic C-11 diols. Polycondensation of the diols with three diacyl chlorides and polyaddition with two diisocyanates produce linear polyesters and polyurethanes, respectively, with furan rings residing in both the polymer backbone and pendent positions. One monomer isomer has a steric advantage, leading to higher molecular weight polymers. Thermal and mechanical properties of the resulting polymers can be tuned in a broad range by varying the monomer pairs. In addition, a thermally reversible cross-linked network has been realized by applying the Diels Alder reaction between a bis-maleimide cross-linker and the furan rings located at both the backbone and pendent positions. This property, coupled with formation of a significant amount (up to 34%) of stable carbonaceous materials when heating the difuranic polymers to 700 degrees C, demonstrates some promising features of this class of new difuranic polymers.