Bubbles with Great Potential!
Molecular Control of Foam Properties

Foams are ubiquitous in our daily lives and in industrial applications. The vast number of possibilities to use foam in processes and products originate from their unique physico-chemical properties. In order to formulate foam with specific properties, its chemistry must be controlled at the molecular level of the ubiquitous gas-fluid interfaces. Molecular-level characterizations of fluid interfaces are essential and help to reveal structure-property relations inside foam. For that reason, we perform experiments on different hierarchical elements, at several length scales - particularly at the molecular level of fluid interfaces. For that, we apply nonlinear optical spectroscopy with femtosec-ond lasers. While the properties of most foams cannot be changed after their formation, a new class of photo-switchable surfactants (arylazopyrazoles) and their 2D assemblies at the air-water interface offer the opportunity to render fluid interfaces as well as macroscopic foam responsive to light irradiation. This opens exciting new possibilities for foams such as self-healing capabilities or the possibility to adapt foam properties by photo-switching of the surfactants.

Björn Braunschweig was born 1979 in Bad Gandersheim and studied Physics at TU Clausthal from 1999 to 2004. After he graduated with a Diploma in Physics, Björn Braunschweig became a re-search assistant in the group of Prof. Winfried Daum at TU Clausthal where he started to study fluid interfaces on a molecular level using electrochemical scanning tunneling microscopy and nonlinear optical spectroscopy. In 2009, he graduated with his PhD thesis “In situ Studies of Solid-Electrolyte Interfaces and their Molecular Structure: Platinum and alpha-Al2O3(0001)” which was awarded with Summa Cum Laude and a Dissertation prize of the TU Clausthal. In 2009, Björn Braunschweig joint the groups of Professors Andrzej Wieckowski and Dana D. Dlott at the University of Illinois at Urbana-Champaign (USA). During his research stay in the Wieckowski lab, he studied electrocatalytic reactions at model surfaces and was supported by a Feodor Lynen fellowship of the Alexander von Humboldt foundation. In 2011, Björn Braunschweig returned to Germany and became a group leader at the Institute of Particle Technology of the Friedrich-Alexander University Erlangen-Nürnberg, where he worked with Prof. Dr.-Ing. Wolfgang Peukert. In 2014, he received a Starting Grant of European Research Council and in 2017 he was appointed as a W1 tenure track Professor in Physical Chemistry at Westfälische Wilhelms University Münster.