Research Activities of Sottmann Group

CO₂ Microemulsions: Properties and Applications

Formulation and characterization of CO₂-containing microemulsions

Overview

Based on the enormous knowledge that has been generated on the self-assembly of amphiphilic molecules such as surfactants, lipids and block copolymers, we combine this knowledge to design, formulate, and characterize novel nanostructured systems. As regards the structure of novel self-assembled systems, our current work deals with two different nanostructured systems. These are supercritical carbon dioxide (scCO2)-based microemulsions on one hand, while the general properties and especially the structure of mixtures of water and  scCO2 are the focus of another research topic. Microemulsions consisting of water, carbon dioxide and surfactant can be formulated with certain surfactants. Following the principle of supercritical microemulsion expansion (POSME, German Patent DE 102 60 815 B4) a low-cost nanoporous material should be achievable by expanding these near- and supercritical microemulsions. Home-made pressure cells allow us to study the phase behaviour and microstructure using DLS and SANS. It is also of great interest to investigate the kinetics and fast dynamic processes in nanostructured systems. The combination of innovative stroboscopic SANS (TISANE) and a stroboscopic high-pressure cell that provides adjustable pressure cycles allows for precise tracking of pressure-induced transformation processes in nanostructured systems [1] such as scCO2-microemulsions [2].

CO2 microemulsions (c)
Figure: (Left) Stroboscopic high-pressure SANS cell (top) to study the kinetics of pressure-induced structural changes. SANS data (bottom) of a gelled bicontinuous microemulsion (black). The fit curve (red) includes contributions of the bicontinuous microemulsion (blue) and of the gelator network (green). (Right) SANS-curves of a CO₂-microemulsion recorded during a pressure jump from 260 bar to 160 bar. Kinetics of the sphere to cylinder transition [2].

References

  1. Müller, A., Oberhoffer, R., Becker, N., Pütz, Y., Strey, R., Wiedenmann, A. and Sottmann, T.: Kinetics of pressure induced structural changes in super- or near-critical CO2-microemulsions. Phys. Chem. Chem. Phys. 16, 18092-18097 (2014). https://doi.org/10.1039/C3CP53790K
  2. Wrede O., Reimann Y., Lülsdorf S., Emmrich D., Schneider K., Schmid A.J., Zauser D., Hannappel Y., Beyer A., Schweins R., Gölzhäuser A., Hellweg, T., Sottmann, T.: Volume phase transition kinetics of smart N-n-propylacrylamide microgels studied by time-resolved pressure jump small angle neutron scattering. Scientific Reports 8, 13781 (2018). https://doi.org/10.1038/s41598-018-31976-4

Cooperations

  • Dr. Ralf Schweins, Group of Large Scale Structures, Institut Laue Langevin, Grenoble, France

Contact

Shih-Yu Tseng
 

Shih-Yu Tseng

PhD Student

Thomas Sottmann
Apl. Prof. Dr.

Thomas Sottmann

Professor

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