Preparation and characterization of polymer-modified template phases

Double layer membrane systems

By the addition of water-soluble polymers, the structure-forming behavior of lyotropic liquid-crystalline systems can be decisively influenced [6, 7, 10, 11, 13]. The introduction of charged polyelectrolytes leads, for example, to the formation of compact multilamellar vesicle structures with a strongly altered swelling capacity [8-10]. The addition of branched sugar-modified polyethyleneimines can induce a morphological transformation from a vesicle phase to a tubular network structure [12]. Polyampholytes, e.g. PalPhBisCarb, can produce similar effects of morphogenesis, as we have recently shown [14]. The resulting template phase can be used for the targeted production of flat gold nanotriangles [15].

Figure 1: Cryo scanning electron micrograph of a vesicular template phase

Cooperation:

• Prof. S.E. Friberg (Clarkson University, USA)
• Prof. Th. Hellweg (Universität Bayreuth)
• Prof. E. Kleinpeter (Universität Potsdam)
• Dr. D. Appelhans (Leibniz Institut, Dresden)

Selected Publications:

Microemulsions

Polymers can be introduced into microemulsions, i.e. thermodynamically stable oil-water-surfactant-cosurfactant mixtures, without appearing of a macroscopic phase separation. Polymers can increase the stability of the surfactant film [16, 20], increase the phase area of the microemulsion [18, 19] or induce the formation of bicontinuous microemulsions [16, 17]. In the presence of polyampholytes, the stability of the surfactant film can be controlled by varying the pH value [3].

Cooperation:

• Prof. S.E. Friberg (Clarkson University, USA)
• Dr. A. Poghosyan (Academy of Science Yerevan, Armenia)
• Prof. E. Kleinpeter (Universität Potsdam)

Selected Publications:

Janus emulsions

Emulsifying two immiscible oil components and water in the presence of surface-active substances can produce so-called Janus emulsions. The following figure shows a photomicrograph of such a Janus emulsion.

Figure 2: Light microscopy of a Janus emulsion

First studies by Friberg et al. have shown that nonionic surfactants (e.g., Tween 80) can stabilize such oil1/oil2 drops [21-23]. Our investigations show that the droplet size can be reduced by the addition of phospholipids [24]. Moreover, it is possible to stabilize Janus emulsions in the presence of gelatin-chitosan mixtures [25]. The resulting Janus emulsions serve as a templating phase for the production of biodegradable scaffold materials [26].

Cooperation:

• Prof. S.E. Friberg (Clarkson University, USA)

Selected Publications: