Geometric confinement governs the rupture strength of H-bond assemblies at a critical length scale

Using theoretical considerations and MD simulation techniques, we show that the rupture strength of H-bond assemblies is governed by geometric confinement effects, suggesting that clusters of at most 3-4 H-bonds break concurrently, even under uniform shear loading of a much larger number of H-bonds. This universally valid result leads to an intrinsic strength limitation that suggests that shorter strands with less H-bonds achieve the highest shear strength. Our finding explains how the intrinsic strength limitation of H-bonds is overcome by the formation of a nanocomposite structure of H-bond clusters, thereby enabling the formation larger, much stronger beta-sheet structures. Our results explain recent experimental proteomics data, suggesting a correlation between the shear strength and the prevalence of beta-strand lengths in biology.