Tough Supramolecular Glasses Enabled by Frustrated Non-Covalent Complexation.

Supramolecular glasses, as noncovalently cross-linked amorphous materials, are hampered by a fundamental trade-off between vitrification and mechanical performance. Here we propose a strategy-"frustrated non-covalent complexation"-inspired by frustrated Lewis pairs to overcome this limitation. This is achieved by installing sterically hindering isopropyl groups adjacent to directional squaramide hydrogen-bonding motifs. Relative to a nonfrustrated control, this design not only generates more loosely packed hydrogen-bonded domains but also shifts the dominant interactions from squaramide-squaramide to squaramide-ester hydrogen bonding. The frustrated system yields a 4.3-fold increase in mechanical toughness in the resulting supramolecular glass, facilitated by efficient energy dissipation through reversible hydrogen-bond rupture. It also enhances interfacial adhesion, functioning as an effective impact-resistant coating that mitigates substrate fracture. Overall, this work establishes frustrated noncovalent complexation as a powerful paradigm for designing high-performance supramolecular glass materials.