Side-chain engineering of supramonomers enables tailorable cross-linked supramolecular polyureas

The integration of tailorable mechanical properties, dimensional stability, and reprocessability is of significance in the design of sustainable polymer materials. Herein, side-chain engineering is employed to fabricate cross-linked supramolecular polymers with customizable mechanical properties. Three kinds of side chains, including methyl, 1-ethyl pentyl, and 1-hexyl nonyl, are used to modify the supramonomers. Through the copolymerization of low-content supramonomers and covalent monomers, cross-linked supramolecular polyureas with a wide range of mechanical properties spanning from rigid plastics to elastic materials are successfully constructed. Specifically, the Young's modulus can be adjusted from 525 to 128 MPa by tuning the side chain of supramonomers from methyl to 1-hexyl nonyl. Meanwhile, the materials still retain exceptional recyclability and solvent resistance. Even after seven generations of recycling processes, the reprocessed cross-linked supramolecular polyureas maintain over 95% of their original mechanical properties. It is anticipated that side-chain engineering is a facile method for designing customized polymer materials to achieve both tailored mechanical properties and desirable functions.