ResearchTopics
Polymers and particles for biomedical applications
Our work on the development of biomedical imaging probes and therapeutic materials includes (macro-)molecular and colloidal systems for the specific recognition and binding of tumor cells or for the selective uptake of toxins. The respective carrier materials consist of bio-inspired polymers, functional swollen polymer networks with a high internal surface area for the absorption of substances and aqueous dispersible semiconductor polymer particles. For biomedical imaging, we are currently concentrating on materials with photoacoustic activity. This allows deep penetration into tissue layers coupled with the principle of ultrasound imaging, but with improved resolution and for the specific labelling of pathogenic tissue. In particular, we are investigating conjugated polymer particles that are biodegradable and are therefore particularly suitable for IR fluorescence or photoacoustic imaging. In combination with plasmonic inorganic nanoparticles, these effects can be further enhanced.
Light-emitting radicals
as molecular spin materials
Light emitting radicals are organic molecules that possess both unpaired electrons and fluorescent properties. Some luminescent radicals exhibit high quntum yields of around unity, T1 spin relaxation times on the ms regime and T2 spin coherence times of the order of µs at room temperature. Light emitting radicals have revently gained attention as efficient electroluminescent emitters as they lack triplet states and can therefore overcome the problem of spin statistics that is inherent to organic singlet state emitters. However, several challenges remain in their photostability, extension of their T2, their field sensitive luminescence, which has only been observed at temperatures as low as 4 K, and the development of high-spin ground states.
Functional Materials by Supramolecular Self-Assembly
Our research is directed towards structure and morphology controlled self-assembling systems. Organic synthesis allows tailoring of the molecular building blocks and programming their capability for self-assembly by fine-tuning the intermolecular interactions. Those interactions are based on rather weak forces like van-der-Waals, π-π, and (weak) C-H…N interactions. Self-assembly takes place in molecular mono- and multilayers, bulk phases, and in solution. The generated assemblies represent functional units on the nanometer scale. Their functionality arises mainly from the molecular functional groups. Here, we are focussing on nitrogen containing heteroaromatic compounds.
Besides molecular self-assembly we are interested in colloidal systems like (nano)emulsions stabilized by various solid entities (Pickering-type stabilization) and structure formation therein.
Small molecules, polymers, and particles for light emitting devices
We synthesize molecules with tailor-made electronic structure to develop distinct electronic properties, unravel the underlying mechanisms, and increase efficiency. To achieve this, we start by designing small molecular entities to understanding structure-property relations and transfer them to macromeolecular constructs and particles to enable upscaling, improve processing from liquids while preserving high performance of the individual small building blocks. Currently we are investigating hot exciton pathways in aligned excipexes, as well as new highly efficient open-shell emitters, and light emitting colloids of complex shape and hybrid (organic/inorganic) composition.
Micro- and Mesogels and their supramolecular interactions
We produce microgels with supramoelcular motifs to use them as scavengers for biomedical applications. These microgels can take up toxins or other types of biomacromolecules that promote inflammation in the body. The microgels are developed as alternative treatments for autoimmune diseases or where antibiotics do no longer work.
Mesogels are like microgels only bigger. We produce these in any desired shape using stereolithographic 3D-printing. We equip our mesogels with distinct and switchable supramolecular motifs to have them self-assemble into predetermined structures. Switchability allows for the possibility to also disassemble these materials, which in the long run could enable self-assembled structures that can reshuffle - upon issueing a trigger - into a different preprogrammed structure, depending on the sequence of switches and triggers.
Polymers and particles for electrode and energy storage applications
We synthesize tailor-made polymers for the production of carbon fibers, whereby we also consider large-scale applicability at an early stage of development. This means that we use commodity monomer building blocks for the synthesis of polymers that are available on a large scale and at low cost. The polymers receive their special functionality through their hierarchical structure. New processing methods are developed so that the polymers become porous upon conversion into carbon fibers. The resulting materials exhibit large surface area and improved electrical capacity. Classically, polymer fibres are converted into carbon fibres in high-temperature processes. We rely on alternative conversion processes that are less energy-intensive and fast (or even instantaneous). We add nanoparticles to the polymer fibers, which absorb either infrared laser light or microwave radiation and convert these into heat. This allows high temperatures to be generated within the fiber, resulting in conversion to carbon fibers without loss of energy.
