Avenues into Complex Materials: Cooperative Projects of the Natural, Engineering, and Biosciences

Jörg J. Schneider Franz Dettenwanger The term “complex material” refers to multicomponent materials with a composite structure and composition. It is characteristic that their typical ensemble properties do not arise from a simple addition of the distinct properties of the individual constituents. Functionality in complex materials is based on the availability of certain stimuli, which are most basically addressed at a discrete molecular level by chemically controlled processes. Combining such discrete molecular processes with higher-order self-organization in the next size regime leads to functionality on the nano- and mesoscale. The final step then is the organization of such entities on the macroscopic level. Arranging and combining objects in such a controlled manner from the subnanometer to the micrometer size regime requires an intimate combination of chemical, biological, and engineering techniques. The understanding and control of such integrated processes is the most important goal in designing complex functional systems. Interdisciplinary research at the borderline of the disciplines has to span the gap between controlled chemical synthesis, the understanding and tailoring of physical properties, as well as the engineering processes and adaptation that are required to produce the finished functional material. On the molecular level this can already be controlled on a very high and sophisticated level, however, routes to the nanoscopic and, from there, to the macroscopic world are only beginning to be unraveled both synthetically and theoretically. In particular, most if not all of our current understanding of complex systems in engineering and the natural and life sciences is based on interdisciplinary research efforts from all of these disciplines. Particularly on the nanoscale, all of these disciplines meet at a playground where the borders of the disciplines are almost completely blurred. Properties of matter on the nanoscale are no longer defined within a single, individual discipline. Due to the special properties associated with any kind of matter in this size regime, the classical borders are lifted and disciplines are essentially unified on the nanoscale. This is an ideal starting point for fostering transdisciplinary work within a long-term cooperatively funded research program. Such a program was inaugurated by the Volkswagen foundation (VolkswagenStiftung) in the year 2000.1 Over the last seven years, more than 140 groups from 10 countries have been funded, all of whom are organized in interdisciplinary, international cluster projects (involving between two and five groups in each project), which combine to make a total of 46 grants with a total level of funding of € 22.2 M (see Figure 1). In order to be accepted into the program, several conditions must be met by each of the scientist’s consortia. The groups had to work on a cross-disciplinary project (naturally requiring at least two groups from different disciplines), and they had to go through two highly competitive evaluation rounds having a 25 % success quota in the first and 55 % success quota in the second round, respectively. At the end of the selection process, the successful projects were granted with attractive funding for the individual partners combined with project management by the funding organization (very important for multi-partner projects often situated in various countries, see Figure 2). Scientific origin of the funded groups in the 46 cluster projects. Geographical distribution of the collaborating and funded groups in the Volkswagen funding initiative “Complex Materials” (Israel, Switzerland, USA, Austria, Netherlands, Russia, Belgium, Ireland, Japan, and Germany, marked with dots; all the mainland European countries are marked with a single dot). Among the funded research projects of the initiative, 18 groups have contributed their latest results to this special issue of Small. Topics dealt with in this issue are in the areas of complex polymer structures (photoluminescence quenching; nanoporous membranes based on triblock polymers; phase separation of polymer nanoparticles), self-assembly of complex composite biostructures (metallization of artificial DNA-duplexes; influence of peptide sequences on specific adhesion of human-skin keratinocytes; biomimetic models of the actin cytoskeleton), porous nanostructures (polymeric microtubes via spinning techniques; nanoporous alumina for biofunctionalization; carbon-nanotube alignment and field emission; ordered polymer fibers via mechanical release from porous structures), research on nanoreservoirs (self-repairing coatings containing active nanoreservoirs; multifunctional polymeric microcapsules; inorganic molybdenum/iron oxide capsules with external and internal surface modifications), and ultrathin surfaces (collagen-based materials for biotechnical applications; self-assembled single- and double-stack π aggregates of chlorophyll derivatives). The contributions were submitted in the form of 14 Full Papers, three Concept articles, and one Review. The topics covered encompass different length scales and domains ranging from the molecular level up to the micrometer regime. It is our sincere hope that the results from these projects will attract the broad and, in a most positive sense, diverse readership of Small. As a large number of acquired results over the complete funding period have already been published elsewhere during the course of the last years, the contributions to this special issue of Small have been selected only after passing the stringent peer-review process of the journal, thus assuring the highest possible quality. We are confident that these contributions will stimulate more groups to undertake this type of cross-disciplinary and international project that encompasses research from the molecular level through to microscale regime. For the groups participating in this project, it has been an ideal opportunity. Last but not least, all projects were substantially inspired and fostered by three international symposia organized by the Volkswagen foundation and active scientists within the initiative. The first was held in Bremen in 2003, the second in Stuttgart in 2005, and very recently, the third was held in Kerkrade, entitled “Converging bottom-up and top-down methods for advanced assembly and functionality”; a report on this symposium can also be found in this special issue. All of our individual disciplines certainly require such cooperative initiatives where first-class fundamental research is funded without any need (or pressure) to produce technologically ‘usable’ results in the short term. It is certain that only cutting-edge research will lead to fascinating new results, which will act as true pacesetters for long-term advances in future technologies, whether they be in the chemistry, physics, biology, or engineering domains.