Chirality plays a significant role in the physical properties and biological functions of many biological materials, e.g., climbing tendrils and twisted leaves, which exhibit chiral growth. However, the mechanisms underlying the chiral growth of biological materials remain unclear. In this paper, we investigate how the Towel Gourd tendrils achieve their chiral growth. Our experiments reveal that the tendrils have a hierarchy of chirality, which transfers from the lower levels to the higher. The change in the helical angle of cellulose fibrils at the subcellular level induces an intrinsic torsion of tendrils, leading to the formation of the helical morphology of tendril filaments. A chirality transfer model is presented to elucidate the chiral growth of tendrils. This present study may help understand various chiral phenomena observed in biological materials. It also suggests that chirality transfer can be utilized in the development of hierarchically chiral materials having unique properties.

The mechanics of battery electrodes are crucial for determining the cycling performance and battery lifetime. In this study, we investigated the fundamental important material properties of commercial carbon electrodes that strongly depend on the Li concentration. An optical system is used to perform in situ measurements of a mesocarbon microbead (MCMB) composite electrode during the electrochemical process in a homemade cell with a glass window. The deformation vs. capacity during the second lithiation is given and, combined with a built elastic modulus equation, the elastic modulus of carbon composite electrode is directly quantitatively characterized herein as a function of Li concentration by in situ experiments. It is found that the mechanical responses of the MCMB composite electrode somewhat depend on the graphite intercalation compound stage behavior. The material stiffening of the MCMB composite electrode is experimentally observed herein. Further, the elastic modulus varies nonlinearly with Li concentration. It initially increases, decreases, and then increases again from an initial value of 98 to a maximum of 194 MPa, which is a stiffening factor of two rather than the expected values of three. This experimental data are useful for understanding the relationship between the mechanics and the electrochemistry.

Tendril-bearing climbing plants must recur to the tendril helices with chiral perversion or dual chirality for climbing and to obtain sun exposure. Despite researchers’ prolonged fascination with climbing tendrils since Darwin’s time and even earlier, why the soft and slender tendrils can bear heavy loads such as the self-weight of a plant or additional load caused by rain remains elusive. In this paper, we take towel gourd tendrils as an example and investigate the macroscopic and microscopic mechanical behaviors of tendrils through experiments and simulations. Our study indicates that the tendril filament exhibits rubber-like hyperelastic behaviors and can particularly endure large elongation, which is mainly attributed to the superelasticity of the cellulose fibril helix contained in the cell wall. Combination of the tendril helical structure with dual chirality or chiral perversion at a macroscale and a cellulose filament helix at a subcellular level creates superior elasticity for biological species relying on support and climbing. This study provides deep insight into the structure–property relationship of climbing tendrils, and the relationship is useful for the bioinspired design of composite systems with superior elasticity.