Supra‐Amphiphiles for Functional Assemblies

Abstract

wileyonlinelibrary.comVarious building blocks can be used to fabricate supra-amphiphiles, ranging from small molecules to polymers, from synthetic compounds to natural chemicals. [31][32][33][34][35][36] The preparation method is adapted to the solubility of these building blocks. The simplest method is to mix all the building blocks together in water or other solvent simultaneously. According to the fast dynamics of the noncovalent interactions, the supra-amphiphiles can spontaneously form and self-assemble in a short time. When some of the building blocks are not readily soluble in water, a good solvent for all building blocks is usually applied. For example, as shown in Figure 1, we mixed a nitrobenzene derivative (DNB) and a pyrene derivative (PYR) in tetrahydrofuran (THF), which is a good solvent for DNB and PYR. [37] The supra-amphiphile could form on the basis of the charge-transfer interaction. The PYR, which was a conventional amphiphile, self-assembled in water to form tubular structures, while the supra-amphiphiles could self-assemble in water to form vesicles. Therefore, the formation of supra-amphiphiles can be regarded as the first-level self-assembly based on the noncovalent synthesis of covalent components, and then the supra-amphiphiles can undergo second-level self-assembly to form well-defined organizations.Abundant studies have been reported on the design, fabrication and application of supra-amphiphiles. In this feature article, we would like to introduce recent progresses of supra-amphiphiles from molecular architecture to functional assemblies. Limited by the volume of this article and our knowledge, it is impossible to cover every aspect of this developing area, therefore, we will put special emphasis on a few topics where supra-amphiphiles function as surfactants, and in the areas of nanocarriers, photodynamic therapies, chemical analysis and functional interfaces. Hopefully, it can reflect in a way that the study on supra-amphiphiles is enriching the molecular engineering of supramolecular systems by combining the molecular architecture and functional assembly. Supra-Amphiphiles as SurfactantsSurfactants, referring to surface-active reagents which can induce significant decrease in interfacial tension by adsorption, are crucial substances for colloidal research, industrial applications as well as our daily life. Supra-amphiphiles can also be utilized as surfactants, functioning in emulsification, foaming, etc. As there is more flexibility in the structure of supra-amphiphiles compared to that of the covalent counterparts, finer tuning of interfacial tension and other physicochemical properties can be realized. In addition, the feature of noncovalent Supra-amphiphiles refer to amphiphiles which are fabricated on the basis of various noncovalent interactions and dynamic covalent bonds, including host-guest interaction, charge-transfer interaction, electrostatic interaction, imine bonds, etc. In this feature article, recent progresses of supra-amphiphiles from molecular architecture to func...

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