Enhancing elasticity of Eucommia ulmoides gum by branch pendant strategy

Eucommia ulmoides gum (EUG) was usually considered as a hard rubber with poor elasticity at room temperature because of its crystallinity, which limited its applications in rubber materials, and the extraction of EUG from the plant tissues was a challenge task. Biobased EUG was efficiently extracted by acid catalysis in ionic liquid, and modified by Alder-ene reaction via the novel triazolinedione containing different branched alkyl groups, enabling it to become soft rubber with greatly improved properties including excellent elastic recovery rate of 92%, high elongation at break of 1311%, low Young's modulus of 0.44 MPa, and low hardness of 50 o , which were comparable to those of natural rubber. Therefore, this sustainable elastomeric material with tunable and enhanced physical and elastic properties would have broadened applications in tires and other rubbery products. • Sustainable Eucommia ulmoides gum (EUG) was extracted in ionic liquid with high yield. • EUG was modified by triazolinedione containing branch group and changed to soft rubber with greatly improved elasticity. • Modified EUG exhibited excellent elastic recovery of 92% and low hardness of 50 o .