Modeling and design of microgels switchable by cononsolvency – volume change kinetics

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Müller, David

Name

David Heinrich Müller

Measurement Systems Engineering

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+49 241 80 90473

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Gels are part of our daily life. Examples include toothpastes, hair gels, paints, and even contact lenses. Whatever the scenario, gels basically consist of cross-linked polymer networks permeated by liquid.

 

Gels with a diameter ranging between 100 nanometers and 100 micrometers are referred to as microgels. Among their many functionalities, microgels respond to a variety of external stimuli such as temperature, pH value, and solvent composition with size change. Poly N-isopropyl acrylamide (PNIPAM), for instance, is swollen in pure liquids like water and methanol. But for certain mixtures (e.g. 80% water and 20% methanol), PNIPAM can show a volume reduction relative to the pure-solvent setup. This phenomenon is known as cononsolvency.

  Schematic representation of cononsolvency Copyright: LTT Fig.: Schematic representation of cononsolvency. In pure water (left) and in pure methanol the microgel is swollen. In mixtures of water and methanol (center) the microgel is deswollen.

Within the framework of the collaborative research centre "Functional Microgels and Microgel Systems", we explore the volume change kinetics of microgels triggered by cononsolvency.

  

At the Chair of Technical Thermodynamics (LTT) the focus of the project is on non-equilibrium thermodynamic modeling of the volume kinetics of spherical microgels. This modeling is linked to experiments which are performed by the Institute of Physical Chemistry (IPC).

 

Project Details

Project Duration

4 Year

Publications

C. Scherzinger, A. Schwarz, A. Bardow, K. Leonhard, W. Richtering; Cononsolvency of poly-N-isopropyl acrylamide (PNIPAM): Microgels versus linear chains and macrogels; COCIS (2014), Volume 19, Issue 2, Pages 84–94.