Unique Temperature-Dependent Supramolecular Self-Assembly: From Hierarchical 1D Nanostructures to Super Hydrogel

Abstract

Supramolecular self-assembly can not only lead to a better understanding of biological systems, but also can enable rational building of complex and functional materials. In this report, hierarchical one-dimensional (1D) architectures involving nanotubes, coiled-coil ropelike structures, nanohelices, and nanoribbons are created via lanthanum-cholate supramolecular self-assembly. These sophisticated self-assemblies are proven to be mediated by temperature. The entanglement of one-dimensional nanostructures is demonstrated to give rise to fascinating "super" hydrogel, which can realize water gelation at extremely low concentration. Unprecedented water gelation behaviors, that is, heating-enhanced stiffness and heating-promoted gelation, are found in lanthanum-cholate supramolecular hydrogel. The driving forces of self-assembled complex nanostructures and the unique role of temperature are also discussed.

A Supramolecular Hydrogel Inspired by Elastin

“…We then characterized the gel-sol phase transition temperature (T gs ) and pH (pH gs ) values of the gel. As shown in Figure 1, similar to other reported results, 39,40 the T gs and pH gs values were concentration-dependent-both of them increased by increasing the amount of 1 in gels (the T gs values were 78, 101, 109, 117, and 123 ℃ and the pH gs values were 8.5, 9.0, 9.8, 11.0, and 11.5 for gels with 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, and 4 wt% of 1, respectively). As shown in Figure 2A and 2B, the gel formed by 1 (gel I containing 3 wt% of 1) was thixotropic, which meant that it could be converted into a solution by shaking or vortex, the solution would then change back to a gel after a period of time (about 1 h for gel I).…”

Gels with sense: supramolecular materials that respond to heat, light and sound

“…Such behaviour was observed by Qiao et al in coordination polymers consisting of cholate and lanthanum ions. 31 Scanning and transmission electron microscopy images reveal the dominant structures at 4 o C to be nanotubes with diameters of 5-23 nm, but increasing the temperature to 15 o C produces ribbons with widths of 10-60 nm and a right-handed helical morphology. Heating to 50 o C, Fig.…”

Synthesis of high-voltage spinel LiNi0.5Mn1.5O4 material for lithium-ion batteries by a metal-cholate supramolecular hydrogel as precursor

“…1, the reticular structure constructed by onedimensional ramifications can be observed distinctly. It has been confirmed that the 1D structures were attributed to the metal-cholate supramolecular system, which have the capability to entangle into a cross-linked network [34]. As we emphasized, we creatively regard the metal-driven hydrogel as the carrier matrix as well as the template in the fabrication of LiNi 0.5 Mn 1.5 O 4 materials.…”