Morphologically and Functionally Tunable Nanostructures Self-Assembled from Azopyridine-Containing Block Copolymers

Abstract

Hierarchical structures with enhanced performances are of growing importance in many fields, but their preparation suffers from tedious and multistep procedures. There remain challenges to transfer and magnify the molecular functions in hierarchical structures to pursue more unique applications. Herein, a facile one-step approach for the fabrication of hierarchical structures assembling from amphiphilic copolymers, poly(ethylene glycol)-block-poly(6-(4-(4-pyridyazo)phenoxy)hexyl methacrylate) (PEG-b-PAzoPy) with controlled morphologies and enhanced functions, is reported. Various hierarchical structures including three-dimensional raspberry-like assemblies, worm networks (WNs), and large compound vesicles are obtained through a heating-cooling-aging process in THF/ethanol. The fluorescence detection of p-nitrophenol at ultralow concentrations (10⁻¹² m) is realized by the formation of nonfluorescent nitrophenol-WNs complexes, taking advantage of the high surface area and unique cavities of WNs. Furthermore, a highly efficient nanofiltration composite membrane is constructed by assembling WNs on the surface of a commercial polypropylene membrane. More interestingly, using simple 2H,2H,3H,3H-perfluoroundecanoic acid as the H-bond donor and PEG-b-PAzoPy as the acceptor, they can form H-bond complexes and further assemble into nanowires with highly ordered liquid crystalline stripes. This study not only offers a facile strategy for the design of hierarchical structures but also facilitates the application of advanced hierarchical materials in various fields.