Research into new functional materials also includes the realization of artificial structures, as found in metamaterials with unusual optical and electrical properties or in the field of soft robotics and artificial muscles. Modern research approaches, which make use of self-organization and confinement effects, go far beyond classical chemical synthesis at the molecular level. Self-organization refers to the spontaneous emergence of spatio-temporal structures and patterns as a result of the interaction of smaller units. This self-organization often occurs under the influence of external or internal limiting effects. A limitation is seen as an effect on a system that restricts the translational and rotational degrees of freedom of its units. The term “stimulus-responsive” refers to materials that experience a change in their properties when they are exposed to a change in the external environment (a stimulus). Ideally, a material responds to a stimulus in a reversible and spatially and temporally resolved manner. Examples are soft matter materials in which comparatively small external stimuli lead to large changes on macroscopic length scales. In a liquid crystal display (LCD), an electrical voltage of a few volts is sufficient to reorient the rod-shaped molecules of a liquid crystal.
Modern functional materials with tailor-made mechanical, optical, electrical or magnetic properties therefore require not only molecularly precise synthesis methods but also the use of (intrinsic) self-assembly and confinement effects as well as the application of simulation technologies to obtain knowledge resulting from data from sensors, digitized collections, experiments and simulations. The SimTech Cluster of Excellence plays an important role here.
One focus of research here is the use of soft matter materials, including polymer melts and solutions, polymer gels, electronically and ionically conductive polymers (mixed semiconductors), polymer foams, fibers and electrolytes, elastomers, liquid crystals, colloids and surfactants. Catalytic polymerization plays a central role in the synthesis of tailor-made polymer materials. In light of these requirements, the Faculty of Chemistry's research approach to such functional materials is based on an intensive, synergistic interplay between chemistry, materials science and simulation.
Stimulus-responsive materials are, e.g., the basis for sensory or actuator systems. Sensory materials react selectively and sensitively to physical or chemical input variables such as light, heat, movement, humidity, pressure, pH value or specific chemical compounds. The combination of electrical stimuli and ionic interactions is of great interest for applications in bioelectronics (e.g. as organic electrochemical transistors) and medical technology. Actuators are systems or materials that, for example, convert electrical signals into mechanical movements or other non-electrical variables (e.g. pressure, temperature) or, conversely, convert mechanical movement into electrical signals (e.g. conjugated or piezoelectric polymers, ferroelectric liquid crystals, electrically or magnetically responsive organic/inorganic hybrid materials). Both sensory and actuator systems are central to current research initiatives, such as the RTG 2948 (“Mixed ion-electron transport: from fundamentals to application”) and the Cluster of Excellence application “Bionic Intelligence for Health”. They are anchored in the new profile area of the University of Stuttgart “Biomedical Systems and Robotics for Health” and the newly founded Center for Bionic Intelligence Tübingen-Stuttgart (BITS).
Confinement effects, which are observed, for example, in catalytic reactions in customized mesoporous inorganic or polymeric materials with defined, directing geometries, are also the central topic of the current Collaborative Research Centre SFB 1333 “Molecular heterogeneous catalysis in confined geometries”. Finally, bio-inspired approaches are also used to realize hierarchically structured architectures with directing properties and stimulus-responsive materials, such as those being researched as part of the “ChitinFluid” project, funded by the Carl Zeiss Foundation.
