Covalent thermosets generally exhibit robust mechanical properties and dimensional stability

but suffer from fragility

intractability and lack of recyclability. After the end-of-life usage

most thermosets are discarded

leading to severe wastes of resources and causing environmental problems. Recently

Xu

Zhang and co-workers proposed a new strategy of incorporating low-content noncovalent bonds into polymer main chains to construct tough and multi-recyclable cross-linked supramolecular polyureas. The polyureas were prepared

via

the copolymerization of quadruple hydrogen-bonded supramonomers and covalent monomers/crosslinkers. It was shown that the remarkable mechanical properties of covalent cross-linked polymers and excellent multiple recyclability of supramolecular polymers were well combined in the cross-linked supramolecular polyureas. The molecular design is simple but elegant. It is anticipated that the similar methodology can be used for making various cross-linked supramolecular polymer materials with superior recyclability and mechanical properties

thus providing a new and general strategy for the preparation of reprocessible and recyclable cross-linked materials.