Controlling the <i>cis</i>/<i>trans</i> Content of Biobased Unsaturated Polyesters by Judicious Choice of a Biosourced Catalyst

Replacing fossil-derived polymers with biobased alternatives is essential to reduce the environmental impact of plastics production, as it helps to decrease reliance on finite fossil resources and promotes sustainability by using renewable raw materials. However, biobased options remain scarce in the industry, as it is difficult to produce fully biobased polymers at a reasonable cost with the same functional properties. In this study, 100% biobased unsaturated polyesters are synthesized from maleic acid and 1,3-propanediol through bulk polycondensation mediated by biosourced catalysts. The resulting materials present different degrees of double bond isomerization depending on the catalyst employed, with higher trans content obtained using catalysts that exhibit greater nucleophilicity. With the objective of using these polyester resins for additive manufacturing, the reactivity of the double bonds was analyzed through FTIR and photo-DSC, while the cross-linking process was studied by photorheology, which highlighted the superior reactivity of the trans double bonds. This study opens avenues for the synthesis of 100% biosourced polyester resins with tunable cis/trans content.