Light-triggered one-pot synthesis of covalent-supramolecular double network elastomer

The double-network (DN) structure is an important strategy for toughening elastomers. Developing efficient preparation methods for DN elastomers remains a key challenge in this field. Herein, we developed a one-pot, single-step strategy to fabricate covalent-supramolecular double-network elastomers by utilizing light to simultaneously form both covalent (CN) and supramolecular networks (SN). In specific, the CN was formed via thiol-ene click chemistry using styrene-butadiene rubber as the backbone, while the SN was constructed through photo-induced crosslinking of poly(ethylene glycol) based polymers mediated by quadruple hydrogen bonding. Mechanical tests revealed that the DN elastomer exhibited significantly enhanced properties compared with the control (pure CN). Specifically, the DN exhibited superior fracture stress (0.74 vs. 0.45 MPa), fracture strain (268 vs. 99%), and toughness (1.47 vs. 0.29 MJ/m 3 ). Cyclic tensile testing and stress-relaxation experiments demonstrated that the superior performance of the DN elastomer was attributed to the excellent energy dissipation capacity of its SN. Furthermore, supramolecular monomers can be introduced into pre-formed CN through swelling, establishing a novel methodology for toughening commercial CN elastomers via the double-network strategy.