Molecular engineering of supramolecular polymer adhesive with confined water and a single crown ether

Abstract

Here, we report a water-induced supramolecular polymer adhesive formed from confined water and an intrinsically amphiphilic macrocyclic self-assembly in a nanophase-separated structure. The selenium-containing crown ether macrocycle, featuring a strong hydrophilic hydrogen-bond receptor (selenoxide) and a synergistic hydrophobic selenium-substituted crown core, confines water within a segregated, interdigitated architecture. While water molecules typically freeze around 0 °C, the confined water in this supramolecular polymer remains in a liquid-like state down to −80 °C. Previous studies suggested that multiple crown ether units are required to generate confined water; however, in this case, a single unit is sufficient to control the formation and disappearance of confined water, driving supramolecular polymerization. Typically, the DC conductivity of water follows an Arrhenius temperature dependency (ln σ_DC ∝ 1/T). In contrast, this new crown ether unit maintains water in confined states, exhibiting Vogel–Fulcher–Tammann behavior (ln σ_DC ∝ 1/(T − T₀)) at temperatures above the glass transition. Moreover, this water-induced supramolecular polymer demonstrates remarkable adhesion to hydrophilic surfaces, maintaining strong adhesion even at low temperatures. These findings illustrate how a single small macrocycle can control the complex structure and functionality of water in supramolecular systems.