On the Influence of the cis/trans Stereochemistry of Limonene Oxides toward the Synthesis of Biobased Thermosets by Crosslinking with Anhydrides

This study emphasizes the reactivity of (R)-(+)-limonene, a major byproduct of the citrus industry, and its potential to be used as a biobased thermoset precursor. We separated the cis and trans limonene epoxides and synthesized limonene dioxide (LDO) monomers using an environmentally friendly epoxidation. Their crosslinking reactivity with glutaric anhydride, a biobased hardener, to obtain fully biobased thermosets was studied. The influence of the stereochemistry of limonene epoxide monomers on the copolymerization, the crosslinking density, and the resulting material properties were investigated. By comparing the cis- and trans-LDO reactivity, for the first time, we found that cis-LDO generates thermosets with high mechanical properties (sigma = 43 MPa; epsilon = 4.56%; E = 1.36 GPa; E' = 1.68 GPa, Shore D hardness = 81), thus establishing this isomer as a very promising biobased epoxy monomer.

Automated summary

This study explores the potential of (R)-(+)-limonene, a major byproduct of the citrus industry, as a biobased thermoset precursor. The findings show that cis-LDO can be used to create highly promising biobased epoxy monomers for the production of high-performance thermoset materials.