2012 Werner Kunz

From left: Reinhard Miller, Debora Berti, Werner Kunz

 Professor Werner Kunz opened a new experimental area at the interface between micellar solutions, ionic liquids and concentrated ionic solutions, by using new combinations of large anions and carefully chosen cations. To these he applied his understanding of colloid chemistry with that of hydrotropes, osmolytes and, most particularly, his profound knowledge of specific-ion effects to invent new substance classes that could be used in new commercial applications. 
   In recent years Werner designed a new family of non toxic surfactants/emulsifiers, based on choline as counterion to long-chain alkyl-carboxylates and -sulfates. The secret is that the natural (and even healthy) choline cation decreases the Krafft temperature so that even long-chain anionic surfactants are soluble in water at room temperature. This finding may open new perspectives for the use of triglycerides from European plants instead of (the environmentally) sensitive palm oil. 
   Werner also managed to make the first room temperature ionic liquids with sodium as simple cation. Another highlight is the combination of a simple (but carefully chosen) anionic surfactant with a standard cationic surfactant so that a true cat-anionic surfactant formulation is liquid at room temperature. This is the first cat-anionic surfactant room-temperature ionic liquid and it has several promising potential applications. 
   In the field of microemulsions, he was able to make low-toxicity systems and new ionic-liquid based microemulsions that are liquid and structured between -50 and +250 C. He has even emulsified efficiently bio-diesel via a colloidal approach and introduced this new system to the chemical engineering world for application. 
   One of the other remarkable achievements by Werner is the discovery of new methods of solubilizing of triglycerides in water with a minimum amount of surfactant and further additives. Here again, the formulation additives were carefully chosen based on his knowledge of hydrotropes and specific-ion effects. He edited in 2010 a reference book on “Specific Ion Effects” which summarises the state of the art in Hofmeister effects, from observation to modelling and usage in products based on colloid science. He is co-author, with Netz and Jungwirth, of the quantitative theory of “matching affinities”. This is a generalization of the simple chaotrope/cosmotrope standard views including dispersion effects. The theory of matching affinities is currently the only one able to provide parameter-free predictions for local inversions of the Hofmeister series. 
   All this recently published work – most of it in high impact journals – will have a large impact not only in the scientific community, but also in industry and particularly novel environmentally friendly applications. In fact, most of Werner’s work is sponsored by industry and many of his inventions led to new and improved products, especially in the field of cosmetics and household products that are already on the market. 
   The self-assembled functional molecular systems he discovered in the last five years are elegant knowledge-based colloidal systems designed by an artful combination of thermodynamics with ion-specificity and surfactant science make him the laureate for the 2012 ECIS-Rhodia prize.