Research at the Department of Physical Chemistry II

Characterization, conception and practical application of complex and nano-structured liquids and their interfaces define the central research interests of the Regensburg Solution Chemistry Group.

The major focus is on homogeneous, transparent and thermodynamically stable liquids, such as solutions of hydrotropes, electrolytes, surfactants, polymers, biomolecules as well as Ionic Liquids and micro-emulsions. Other systems such as emulsions, or structured solutions in supercritical carbon dioxide are also investigated. The self-organisation of molecular liquid systems and specific ion effects in nature and technology are in the centre of interest, as well as resulting nanostructures and specific crystallization processes.

The Solution Chemistry Group is especially concerned with the formulation of sustainable, biocompatible products and related processes. These can be cleaning agents, cosmetics etc. or green plant extraction and refining processes.

In particular, we consider the:

• understanding of the interplay of subtle interactions in liquids and the resulting structures. For example, electrostatic interactions versus hydrophobic ones or the appearance of surfactant-free microemulsion structures. We also try to understand such subtle interactions in biological systems and in solutions containing biological molecules, such as antioxidants, proteins etc.
• conception of environmentally friendly solvents, surfactants, and other solubilizers (hydrotropes) and liquid solutions for chemical and industrial processes as well as new sustainable products.
• environmentally friendly extraction of plants (essential oils, natural antioxidants, biopolymers etc.) for the design of highly added value chemicals based on renewable feed stocks (not for fuel production). The vision is a European agriculture that becomes more and more independent of subsidizing and instead produces valuable foods and green chemicals and products.
• Formulation Chemistry: making new, sustainable cleaning agents, cosmetics, galenic formulations, paint formulations, …

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To characterize structure, dynamics, reaction kinetics, and thermodynamic properties of such systems, a multitude of experimental and theoretical methods is employed. From the viewpoint of basic research the interplay between solvation and association, between hydrophobic and electrostatic interactions, is explored to understand the self-organisation of molecular systems and its consequences on the macroscopic properties of the sample. In particular, we are interested in weak interactions [240] and spontaneous organization of matter without template.

The gained knowledge is rapidly transferred to applied research. For instance, new green solvents and surfactants and environmentally friendly Ionic Liquids are designed, to formulate new products such as powerful, but almost drinkable anti-graffiti sprays, green insect repellents, anti-odorizing products and, more recently new types of biofuels, etc. (see Formulation Chemistry). In the last years, our formulation efforts have been completed by new and also environmentally friendly concepts, systems and processes for effective plant extraction and further processing and valorisation of plant extracts.

Generally, the necessary high-precision equipment is designed and developed by the group in collaboration with the faculty workshops. More sophisticated experiments such as neutron scattering, or special microscopy techniques are performed at various international research centres and institutes

Please click on the following?link?to take a view on our?Equipment and Laboratories

For efficient support?in theory and simulation, we have close collaborations with?Prof. Dominik Horinek?and his group.

In order to transform the obtained knowledge to the design of industrial products or new technical processes, the?SKH Company for applied and technical chemistry was founded in 1999. The firm is recognized as an associate institute of the University of Regensburg. This company also offers services in the field of product formulation, especially of cosmetics, household products and pharmaceutics.

Our research group is also a member of the 2012 founded?Carl-von-Carlowitz Centre?of Sustainable Chemistry in our faculty. Prof. Kunz is head of this centre. Carl von Carlowitz is supposed to be the first German having used the word “nachhaltig” (sustainable), in 1713.

OUR CURRENT RESEARCH

can be subdivided into nine topics all related to solution chemistry. Please follow the links below to learn more about specific subjects:??

• Solvents and Hydrotropes
• Ionic Liquids and Deep Eutectics
• Surfactants, Micelles and Microemulsions
• Surfactant-free Microemulsions - the pre-Ouzo Effect
• Plant Extraction
• Formulation Chemistry
• Aqueous and Non-aqueous Electrolyte Solutions
• Specific Ion Effects, Hofmeister Series, Salting-in and Salting-out
• Crystallisation, Nanocrystals, Biomorphs and Silica Gardens

Note that we are working on several more topics of minor extensiveness, mostly in collaboration with colleagues all over the world. The behaviour of polymers in aqueous solutions and adsorbed to solid surfaces, as studied by AFM might be of interest for a broad readership [66,71] as well as the unified concept of curvature, packing parameter and hydrophilic-hydrophobic difference in surfactant solutions [138].?We mention also our efforts on the synthesis in hydrothermal water [177,187,196], our collaboration on self-organising alginate gels [102,111,231] and the use of dissolved chitin to make new bio-based materials [263,264,267]. In [296] we collaborated with a car company about stability of coatings and in [266] and [312], we report on the extraction and stabilisation of natural rubber latex out of Russian dandelion.

Werner Kunz receiving the Gay-Lussac-Humboldt award in 2014 and the Steinkopff award in 2019.