A Dual-Responsive Supra-Amphiphilic Polypseudorotaxane Constructed from a Water-Soluble Pillar[7]arene and an Azobenzene-Containing Random Copolymer

Abstract

Macromolecular supra-amphiphiles refer to a kind of macromolecular amphiphiles whose hydrophlic and hydrophobic parts are connected by noncovalent forces. They have applications in various fields, such as drug delivery, sensor systems, and biomedical materials. Here we report a novel molecular recognition motif between a new thermoresponsive water-soluble pillar[7]arene (WP7) and an azobenzene derivative. Furthermore, we utilized this recognition motif to construct the first pillararene-based supra-amphiphilic polypseudorotaxane which can self-assemble to form vesicles in water. Due to the dual-responsiveness of the molecular recognition motif (the thermoresponsiveness of WP7 and photoresponsiveness of azobenzene), the reversible transformations between solid nanospheres based on the self-assembly of the polymer backbone and vesicles based on the self-assembly of the supra-amphiphilic polypseudorotaxane were achieved by adjusting the solution temperature or UV-visible light irradiation. These dual-responsive aggregation behaviors were further used in the controlled release of water-soluble dye calcein molecules.

Supramolecular control over thermoresponsive polymers

“…In this context, a very recent report by Huang et al describes the reversible switching between micellar and vesicular structures by the application of temperature or light stimuli [76]. The authors synthesized an amphiphilic copolymer based on polystyrene decorated with 12 mol% azobenzene units, that formed host-guest complexes with methoxy-tri(ethylene glycol) (mTEG) functionalized pillar [7]arene [77].…”

“…(a) TEM image of an aqueous solution of 7.00 mM of the copolymer and 1.00 mM of the pillar[7]arene upon heating to 608C; (b) DLS result of (a); (c) TEM image of the same aqueous solution after further cooling to 258C; (d) DLS result of (c). Adapted with permission from Ref [76]. Copyright (2015), American Chemical Society.…”

Role of Aromatic Interactions in Temperature-Sensitive Amphiphilic Supramolecular Assemblies

“…In this context, there is a notable interest in temperature-sensitive systems, as these facilitate convenient extrinsic control over self-assembly. 11–17 Oligo- and poly-ethylene glycol (OEG and PEG) based systems have attracted considerable attention, because of their hydrogen bonding based interactions with water that affords temperature-dependent hydrophilicity. 18–20 In these cases, aggregation becomes stronger at higher temperatures, 21,22 because the loss of hydrogen bonding between the temperature-sensitive functionalities and water reduces the amphiphilie’s hydrophilicity.…”

Fast Photoinduced Large Deformation of Colloidal Spheres from a Novel 4-arm Azobenzene Compound

“…27 A very feasible way to prepare colloidal particle is through the self-assembly of amphiphilic polymers in selected solvents, which can be potentially used in drug delivery systems, nanoreactors, photonic bandgap (PBG) crystals and others. [28][29][30][31][32][33][34][35][36][37][38][39][40] In recent years, the effort to produce nonspherical colloids from spherical colloids has aroused significant interest, which can be potential used in photonic band gap (PBG) crystals and others.…”