The quest for widespread applications especially in extreme environments accentuates the necessity to design materials with robust mechanical and thermodynamic stabilities. Almost all existing materials yield temperature-variant mechanical properties, essentially determined by their different atomic bonding regimes. In general, weak non-covalent interactions are considered to diminish the structural anti-destabilization of covalent crystals despite the toughening effect. Whereas, starting from multiscale theoretical modeling, we herein reveal an anomalous stabilizing effect in cellulose nanocrystals (CNCs) by the cooperation between the non-covalent hydrogen bonds and covalent glucosidic skeleton, namely molecular levers (MLs). It is surprising to find that the hydrogen bonds in MLs behave like covalent bindings under cryogenic conditions, which provide anomalously enhanced strength and toughness for CNCs. Thermodynamic analyses demonstrate that the unique dynamical mechanical behaviors from ambient to deep cryogenic temperatures are synergetic results of the intrinsic temperature dependence veiled in MLs and the overall thermo-induced CNC destabilization/amorphization. As the consequence, the variation trend of mechanical strength exhibits a bilinear temperature dependence with ~ 77 K as the turning point. Our underlying investigations not only establish the bottom–up interrelations from the hydrogen bonding thermodynamics to the crystal-scale mechanical properties, but also facilitate the potential application of cellulose-based materials at extremely low temperatures such as those in outer space.

Understanding molecular interactions between oil and reservoir matrix is crucial to develop a productive strategy for enhanced oil recovery. Molecular dynamics simulation has become an important method for analyzing microscopic mechanisms of some static properties and dynamic processes. However, molecular modeling of shale oil and reservoir matrix is still challenging, due to their complex features. Wettability, which is the measurement of oil-matrix interactions, requires in-depth understanding from the microscopic perspective. In this study, the density, interfacial tension and viscosity of eleven common components in shale oil are calculated using molecular dynamics simulations. Then a molecular model of Gulong shale oil is built, based on the reported experimental results and simulations. Compared with the variation in hydrocarbon content, the change in polar component content leads to more significant variations in the physical properties of shale oil. This molecular model is also employed to investigate the wettability of shale-oil nanodroplets on minerals and organic matter, with or without the surrounding aqueous phase. This work suggests fresh ideas for studying the oil-matrix interactions on the nanoscale and provides theoretical guidance for shale oil exploitation.