Figure 1.

Supramolecular building blocks and their self‐assembly into fibers. a) Molecular structures of bivalent (B)‐type and monovalent (M)‐type molecules as the supramolecular building blocks and additives. For UPy‐PEG‐UPy, n is on average 226 (M _n = 10 kDa). b) Representative Cryo‐TEM images showing the morphology of fibers assembled from B‐type and M‐type molecules at different molar ratios. The ureido‐pyrimidinone (UPy)‐based molecules self‐assemble into fibers (of multiple stacks) at physiological pH and temperature, through dimerization via quadruple hydrogen bonds, and lateral stacking induced by flanking urea moieties forming a hydrophobic pocket shielded from the water. Scale bars = 100 nm.