| Autor: |
Ziegler K; Organic Chemistry Institute and Center for Soft Nanoscience, University of Münster, Corrensstraße 40, 48149 Münster, Germany., Schlichter L; Organic Chemistry Institute and Center for Soft Nanoscience, University of Münster, Corrensstraße 40, 48149 Münster, Germany., Post Y; Organic Chemistry Institute and Center for Soft Nanoscience, University of Münster, Corrensstraße 40, 48149 Münster, Germany., Gröschel AH; Bavarian Center for Battery Technology (BayBatt) and Bavarian Polymer Institute (BPI), University of Bayreuth, Universitätsstraße 30, 95448 Bayreuth, Germany., Ravoo BJ; Organic Chemistry Institute and Center for Soft Nanoscience, University of Münster, Corrensstraße 40, 48149 Münster, Germany. |
| Abstrakt: |
Responsive nanomaterials that can undergo reversible changes in morphology are interesting for the development of functional materials that interact with and respond to their environment. Amphiphilic block copolymers are well-known for their ability to create a wide range of supramolecular nanostructures in solution. Arylazopyrazoles (AAPs) are versatile molecular photoswitches, which change their configuration and hydrophobicity upon irradiation with UV light (365 nm, Z isomer, less hydrophobic) and green light (520 nm, E isomer, more hydrophobic). In this work, photoswitchable block copolymers containing arylazopyrazole tetraethylene glycol methacrylate (AAPMA) and oligo(ethylene glycol) methacrylate (OEGMA) forming amphiphilic POEGMA- b -PAAPMA with varying block lengths are prepared by RAFT polymerization. The photochemical properties of AAP persist in the polymers. Due to their amphiphilic structure, the polymers self-assemble into supramolecular morphologies in water. Remarkably, photoisomerization results in a reversible change in the self-assembly behavior. Specifically, spherical and cylindrical micelles are observed for POEGMA 33 - b -PAAPMA 47 when illuminated with green or UV light during assembly. Furthermore, the morphology of assembled structures can be reversibly switched by subsequent irradiation with UV and green light. |
