Sustainable elastomer of triazolinedione-modified Eucommia ulmoides gum with enhanced elasticity and shape memory capability

Sustainable Eucommia ulmoides gum (EUG) was a biomaterial with the molecular structure of trans-1,4-polyisoprene and poor elasticity, and was usually considered as a hard rubber with a limited applications in rubber products. Triazolinedione (TAD)-based Alder-ene reaction was used to modify EUG to precisely tune the mechanical properties and effectively improve the elasticity by reducing crystallinity, introducing urazole groups, and forming hydrogen bonds between EUG molecules. By adjusting TAD feed, the modified EUG could become an excellent tough elastomer with combined high strength, elongation, and toughness; or a unique rubber with superhigh elongation, low Young's modulus, and good elastic recovery rate. Furthermore, the modified EUG displayed enhanced shape memory capability with fast shape recovery speed, high cyclic shape recovery rate after 10-cycle deformations, and large shape memory recoverable deformation. Therefore, these elastomers may have extended applications in tires and smart materials.