Facilitating biobased epoxidized natural rubber (ENR) vitrimer with biodegradable-renewables and reprocessability is a facile strategy to reduce environmental pollution and the carbon emission evoked by waste vulcanized rubber. Herein, oxidized starch with 57% carboxyl content (OST-57) was fabricated by H2O2/Cu2+ oxidation and served as a bio-macromolecular cross-linking agent. When OST and ENR latex were mixed and subjected to thermal processing, the β-hydroxyl ester bonds between OST-57 and ENR were formed and covalent topology networks were constructed. Consequently, the cross-linking density dominated the comprehensive performance of this novel biobased ENR vitrimer, and enabled it to achieve a high elongation at break (1108%), elastic recovery (90%), shape fixed ratio (99.5%), and shape recovery ratio (95.6%) when the content of OST-57 was 30 phr. Meanwhile, due to the low activation energy (E a) (80.3 kJ/mol) of transesterification, the ENR/OST-57 vitrimer exhibited sound thermo-activated reprocessability, and its loss in mechanical properties was lower than 12% even after being subjected to thermal reprocessing twice. Noteworthily, different from those of the presented vitrimer, ENR/OST-57 showed a distinctive biodegradable-renewable feature when α-amylase was adopted and destroyed the cross-linking network. As a result, the biodegradable ENR with residual β-hydroxyl ester bonds presented similar features as the neat ENR when diisopropylbenzene peroxide was utilized to form the chemical bond cross-linking topology networks. This novel strategy of fabricating biobased vitrimer will promote ENR for wide applications in the field of high ductility and recovery without environmental impact.

The defects of conductive hydrogels, such as high internal friction, poor performance at freezing temperatures, and evaporation during long-term storage, restrict their application in wearable electronics.

No abstract