Polymers and particles for application in soft photonics and optoelectronics
We develop synthetic methods and protocols for the generation of polymer semiconductor particles with uniform size. To achieve this, we adapt established dispersion polymerization procedures to the step growth polymerization mechanism, by which semiconducting polymers are usually produced. To understand these processes, we rely on established analytical methods of polymerization kinetics. The resulting particles are assembled by colloidal self-arrangement (e.g. during a drying process) into crystalline and optically active structures. We use so-called co-assembly methods with inorganic dielectrics (electrical insulators) or semiconductors to precisely adjust the electronic properties and energy transfer processes of such hybrid organic/inorganic devices. This enables us to create unprecedented, precisely nanostructured photonic structures without having to resort to time- and cost-intensive top-down nanostructurization.
S. Ciftci, F. Jansen, V. Chimisso, J. Kler, K. Rahimi, A. J. C. Kuehne, “Horner-Wadsworth-Emmons dispersion polymerization for the production of monodisperse conjugated polymer particles at ambient conditions”, Polymer Chemistry 2018, 9, 2428–2433.
V. H. K. Fell, A. Mikosch, A.-K. Steppert, W. Ogieglo, D. Canneson, M. Bayer, A. Greilich, A. J. C. Kuehne, “Synthesis and optical characterization of hybrid organic/inorganic heterofluorene polymers”, Macromolecules 2017, 50, 2338–2343.
S. Ciftci, A. Mikosch, B. Haehnle, L. Witczak A. J. C. Kuehne, “Conjugated Polymer Core-Shell Particles via Seeded Knoevenagel Dispersion Polymerization - Laser Action in Whispering Gallery Mode Resonators”, Chemical Communications 2016, 52, 14222–14225.
A. Mikosch, S. Ciftci, A. J. C. Kuehne, “Colloidal crystal lasers from monodisperse conjugated polymer particles via bottom-up co-assembly in a sol-gel matrix”, ACS Nano 2016, 10, 10195–10201.
A. Mikosch, A. J. C. Kuehne, “Encapsulation of polymer colloids in a sol-gel matrix – Direct Writing of coassembling organic-inorganic hybrid photonic crystals”, Langmuir 2016, 32, 2567–2573.
S. Ciftci, A. J. C. Kuehne, “Monodisperse conjugated polymer particles via Heck coupling - A kinetic study to unravel particle formation in step-growth dispersion polymerization”, Macromolecules 2015, 48, 8389–8393.
N. Anwar, T. Willms, B. Grimme, A. J. C. Kuehne, ”Light-Switchable and Monodisperse Conjugated Polymer Particles”, ACS Macro Letters 2013, 2, 766–769.
A. J. C. Kuehne, M. C. Gather, J. Sprakel, ”Monodisperse conjugated polymer particles by Suzuki–Miyaura dispersion polymerization”, Nature Communications 2012, 3, 1088.
During synthesis, we can also use (organic or inorganic) nanoparticles as nucleation seeds to generate novel and complex (hybrid) structures (such as core-shell, multi-shell particles, etc.). Alternatively, we can grow swollen polymer networks around the fluorescent core particles, resulting in extremely soft and reconfigurable material systems. As a result, crystalline colloidal assemblies can be melted and recrystallized reversibly by controlling temperature or pH. These material systems are suitable as sensors or switchable reflectors as well as new printable components for optical and electronic systems and counterfeiting and security features.
D. Go, D. Rommel, Y. Liao, T. Haraszi, J. Sprakel, A. J. C. Kuehne, “Dissipative disassembly of colloidal microgel crystals driven by a coupled cyclic reaction network”, Soft Matter 2018, 14, 910–915.
D. Go, D. Rommel, L. Chen, F. Shi, J. Sprakel, A. J. C. Kuehne, “Programmable Phase Transitions in a Photonic Microgel System – Linking Soft Interactions to a Temporal pH Gradient”, Langmuir 2017, 33, 2011–2016.
D. Go, T. E. Kodger, J. Sprakel, A. J. C. Kuehne, ”Programmable co-assembly of oppositely charged microgels”, Soft Matter 2014, 10, 8060–8065.