Smaller is Stronger: Topological Load-bearing of Crumpled 2D Macromolecule

Two-dimensional (2D) macromolecules are atomically thin materials capable of forming crumpled configurations with complex topologies, defining a new paradigm in macromolecular mechanics. Here, we unveil a universal negative size effect, where smaller sheets yield substantially stronger load-bearing capabilities than larger ones. Coarse-grained molecular dynamics simulations demonstrate a negative scaling between compression pressure or modulus and the Föppl-von Kármán number, with the power index determined by crumpling density but independent of material type. Energy analysis indicates that smaller sheets form dense ridge networks with minimizing self-folding, enabling efficient load transfer and energy absorption. During densification, a constant ridge-to-vertex increment ratio of 1.5 preserves the superior ridge density of small sheets. Experiments on paper, aluminum foil, polydimethylsiloxane (PDMS), and silicone rubber confirm this behavior across disparate length scales and across material classes. This work reveals the mechanics underlying size-dependent crumpling in 2D macromolecules and provides principles for designing structural metamaterials with tunable load-bearing characteristics.