Supramolecular Depolymerization of Nanowires Self-Assembled from Micelles

Abstract

Supramolecular polymerization has been a fascinating frontier of supramolecular chemistry in fabricating well-defined hierarchical nanostructures. However, the reverse process, that is, supramolecular depolymerization in which superstructures disassemble into subunits, is far less explored. In particular, the mechanism and kinetics of supramolecular depolymerization have not yet been reported. In this work, we discovered a thermal-induced supramolecular depolymerization of nanowires formed by supramolecular step-growth polymerization of preassembled micelles. With increasing temperature, the intermicelle interaction between the micellar subunits is broken, resulting in depolymerization of the nanowires into micellar subunits. Accompanying the supramolecular depolymerization, chain transfer between the subunits occurs. A theoretical model was proposed to reveal the mechanism and kinetics of the supramolecular depolymerization. It was found that the depolymerization behavior obeys the rules of random depolymerization. The present work could provide useful information for understanding the underlying principles of supramolecular degradation. In addition, the temperature-induced supramolecular depolymerization of hierarchical nanostructures may find potential applications in biomedical fields.

pH‐Controlled Hierarchical Assembly/Disassembly of Multicompartment Micelles in Water

“…This disassembly is rather unusual, as MCMs tend to undergo morphological transitions from smaller to larger aggregates (e.g., spherical micelles to worms) or they separate into patchy micelles. [ 42,44,48 ] The herein described process shows that also hydrophobic core domains are able to disassemble into individual chains in water (given low T g and large enough corona), which might be useful for delivering hydrophobic drugs that are released not with chemical triggers, but by mechanical stress.…”

Depolymerization of supramolecular polymers by a covalent reaction; transforming an intercalator into a sequestrator

“…In supramolecular polymerization, the lability of the non-covalent interactions makes the structures intrinsically dynamic and sensitive to changes in molecular functionalities and external conditions. Therefore, aside from increase in temperature, [10][11][12][13] addition of cosolvent, 14,15 and use of supramolecular additives, [16][17][18][19] the modication of structural units by covalent reactions would provide an alternative method to control supramolecular polymerization. Elegant examples have been presented in which adaptation, regulation and replication can be demonstrated by integrating chemical reactions with polymerization processes.…”

Directional effect on the fusion of ellipsoidal morphologies into nanorods and nanotubes

“…44 Cai and co-workers have well-demonstrated that one-dimensional nanowires readily formed via the fusion of spindle-like micelles along the long axis of the micelles. 45,46 We envision that it might also undergo a directional fusion of ellipsoidal morphologies during the formation of cylindrical nanostructures via PISA of BCPs containing a LC block. However, to the best of our knowledge, the directional fusion effect on the formation of cylindrical nanostructures has been rarely discussed in PISA.…”