Micellen als chemische Nano‐Laboratorien

Loaded nanomicellar structures in water with potentional application in cosmetics such as sun protection and care of sunburn were developed on establishing chemical experiments for teaching without requiring hazardous chemicals, however, concerning an actual field of research. Such micellar systems in water may form „nano laboratories“, for example for the application of lipophilic substances in water. This is demonstrated for fluorescent dyes and lipophilic pH indicators. Finally, supramolecular functional units were stabilized in such structures inducing their operation by interaction. Such micelles may be variously applied in chemical didactics beginning from tests for demonstration, and moreover, for basic and advanced chemical education of students.     

Translating Thermal Response of Triblock Copolymer Assemblies in Dilute Solution to Macroscopic Gelation and Phase Separation

The thermal response of semi‐dilute solutions (5 w/w%) of two amphiphilic thermoresponsive poly(ethylene oxide)‐b ‐poly(N ,N ‐diethylacrylamide)‐b ‐poly(N ,N ‐dibutylacrylamide) (PEO₄₅‐PDEAm_x‐PDBAm₁₂) triblock copolymers, which differ only in the size of the central responsive block, in water was examined. Aqueous PEO₄₅‐PDEAm₄₁‐PDBAm₁₂ solutions, which undergo a thermally induced sphere‐to‐worm transition in dilute solution, were found to reversibly form soft (G ′≈10 Pa) free‐standing physical gels after 10 min at 55 °C. PEO₄₅‐PDEAm₈₉‐PDBAm₁₂ copolymer solutions, which undergo a thermally induced transition from spheres to large compound micelles (LCM) in dilute solution, underwent phase separation after heating at 55 °C for 10 min owing to sedimentation of LCMs. The reversibility of LCM formation was investigated as a non‐specific method for removal of a water‐soluble dye from aqueous solution. The composition and size of the central responsive block in these polymers dictate the microscopic and macroscopic response of the polymer solutions as well as the rates of transition between assemblies.