Large-scale production of ureido-cytosine based supramolecular polymers with well-controlled hierarchical nanostructures

A novel supramolecular polymer containing urea-cytosine (UrCy) quadruple hydrogen-bonding moieties that possesses a high association constant (K_a > 10⁶ M^-1) was synthesized at high yield (96%) at kilogram-scale. The synthesized telechelic macromer dissolved in solution can undergo a substantial change in solution viscoelasticity and can self-assemble due to the noncovalent nature of supramolecular polymerization. As the concentration of UrCy in solution was increased, the spherical assemblies gradually transformed to an ordered lamellar phase with an extremely high degree of polymerization. In addition, the dynamic behavior of UrCy units induced a sudden phase transition in the bulk state, revealing an interesting order-disorder transition from a crystalline solid to liquid state. This newly-discovered material has excellent polymer-like features that are distinct to existing systems. A simple path for forming supramolecular polymers is recommended for the design, large-scale production and manipulation of self-assembled materials with distinctive properties.