Anion‐Coordination Foldamer‐Based Polymer Network: from Molecular Spring to Elastomer.

Foldamer is a scaled‐down version of coil spring, which can absorb and release energy by conformational change. Here, polymer networks with high density of molecular springs were developed by employing anion‐coordination‐based foldamers as the monomer. The coiling of the foldamer is controlled by oligo(urea) ligands coordinating to chloride ions; subsequently, the folding and unfolding of foldamer conformations endow the polymer network with excellent energy dissipation and toughness. The mechanical performance of the corresponding polymer networks shows a dramatic increase from P‐L2UCl (non‐folding), to P‐L4UCl (a full turn), and then to P‐L6UCl (1.5 turns), in terms of strength (2.62 MPa; 14.26 MPa; 22.93 MPa), elongation at break (70 %; 325 %; 352 %), Young's modulus (2.69 MPa; 63.61 MPa; 141.50 MPa), and toughness (1.12 MJ/m3; 21.39 MJ/m3; 49.62 MJ/m3), respectively, which is also better than those without anion centers and the non‐foldamer based counterparts. Moreover, P‐L6UCl shows enhanced strength and toughness than most of the molecular‐spring based polymer networks. Thus, an effective strategy for designing high‐performance anion‐coordination‐based materials is presented. [ABSTRACT FROM AUTHOR]