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

Two-dimensional (2D) macromolecules represent atomically thin materials that can form vast crumpled configurations with complex topological microstructures in confined space, establishing a new frontier in macromolecular mechanics. Here, we unveil a universal negative size effect, where smaller sheets yield substantially stronger load-bearing capabilities than larger ones. Through coarse-grained molecular dynamics simulations, we find a negative scaling relationship between compression pressure or modulus and Föppl–von Kármán number, with the power index governed by crumpled density, independent of material parameters. Energy landscape analysis reveals that smaller sheets preferentially develop concentrated ridge networks with minimal self-folding, creating more efficient pathways for load transfer and strain energy absorption. During densification, we observe a universal topological evolution pattern where the ridge-to-vertex increment ratio maintains a constant 1.5, securing advantageous ridge density of smaller sheets throughout compression. Experimental validations across paper, aluminum foil, polydimethylsiloxane, and silicone rubber substantiate this size-dependent behavior transcending molecular to macroscopic scales. This study deepens our understanding of 2D macromolecule mechanics, establishing fundamental principles for engineering next-generation structural metamaterials with precisely tailored load-bearing characteristics.