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Neueste Veröffentlichungen
Anmol Arya, Solomon L. Joseph, Francois Vonau, Jean-Luc Bubendorff, Silvia Siegenführ, Laurent Simon, Günter Reiter. J. Phys. Chem. C, published online
In the course of electrospraying in a vacuum, polymers acquire electric charges, which are distributed along their backbone. Here, we demonstrate that these charges have a strong impact on the molecular ordering and spectroscopic properties of conjugated polymers when deposited on substrates with an insulating oxide layer. To this end, we electrosprayed varying amounts of poly(3-hexylthiophene) (P3HT) onto silicon substrates with oxide layers of different thickness. The resulting morphologies were explored by atomic force microscopy. The corresponding spectroscopic properties, including their changes in time upon illumination, were derived from photoluminescence (PL) measurements. On insulating substrates, charges were retained on the polymer chains, causing long-range electrostatic repulsion and the formation of largely separated droplet-like objects containing multiple chains. These objects exhibited significant PL intensities for photons with a wavelength (λ) less than ca. 600 nm, suggesting the lack of π–π stacking interactions between P3HT chains. (more...)
Reversible Metamorphosis of a Conjugated Polymer Induced by Photoexcitation
Solomon Joseph, Anmol Arya, Günter Reiter. Advanced Photonics Research 7 (2026) e202500311
Optoelectronic properties of materials are frequently examined through spectroscopic tools based on the absorption and emission of (visible) photons. Typically, one assumes that these transient characterization processes do not cause observable change of these properties because of the low power of the employed light sources. However, for flexible conjugated polymers in a medium of low viscosity, it is decidedly unclear whether photoexcitation of electrons on the backbone of a long polymer chain has an influence on macromolecular conformations and the corresponding intermolecular interactions. Here, we provide clear experimental evidence that continuous absorption of photons progressively causes persistent changes in the spectroscopic properties of conjugated polymers, accompanied by microscopically observable changes in their spatial distribution within a low-viscosity matrix. By contrast, all these changes were completely absent in nonilluminated parts of the same sample.(more...)
Temperature dependence of crystal – melt coexistence for supported polyethylene filaments
Da Huang, Thorsten Hugel, Bizan N. Balzer, Günter Reiter. Nature Communications 16 (2025) 11127
The broken symmetry of molecular interactions at interfaces is causing that crystals are often covered by a thin liquid layer of their own melt. Such crystal–melt coexistence can be related to phenomena of surface premelting, secondary nucleation and melting point depression, particularly important for small systems. Here, we employed intermittent-contact mode atomic force microscopy imaging on nanoscopic semi-cylindrical filaments of polyethylene on a substrate to observe that these filaments contained a crystalline core bounded by molten regions of rather uniform width, W_soft= (9 ± 2) nm at room temperature, which increased reversibly with temperature T. Filaments smaller than ca. 2∙W_soft (T) were completely molten. The values of W_soft (T) compared favorably with theoretically predicted characteristic length scales in the context of nucleation, surface premelting and the melting point depression of finite size crystals. Altogether, we show that these three phenomena are related and dominated by the intermolecular forces acting at crystal surfaces. (more...)
Liste der Veröffentlichungen
- Continuous illumination of a conjugated polymer causes strong enhancement of photoluminescence
- Yaser AlShetwi, Daniel Schiefer, Michael Sommer. Günter Reiter. J. Phys. Chem. B 125 (2021) 5636–5644
- Formation of Stacked Three-Dimensional Polymer “Single Crystals”
- Zhixin Guo, Shouke Yan, Günter Reiter. Macromolecules 54 (2021) 4918–4925
- Measurements of periodically perturbed dewetting force fields and their consequences on the symmetry of the resulting patterns
- Konstantinos Roumpos, Sarah Fontaine, Thomas Pfohl, Oswald Prucker, Jürgen Rühe, and Günter Reiter. Scientific Reports 11 (2021) 13149
- Changes in surface free energy and surface conductivity of carbon nanotubes/polyimide nanocomposite films induced by UV irradiation
- Baode Zhang, Marialaura Clausi, Barbara Heck, Susanna Laurenzi, Gabriella Santonicola, Janis Kleperis, Andris Antuzevičs, Guenter Reiter, Andrey Aleshin, Anatoly Lobach. ACS Appl. Mater. Interfaces 13 (2021) 24218–24227
- Surface-modified elastomeric nanofluidic devices for single nanoparticle trapping
- Deepika Sharma, Roderick Y. H. Lim, Thomas Pfohl and Yasin Ekinci. Microsystems & Nanoengineering 7 (2021) 46
- Optimization of Nanofluidic Devices for Geometry-Induced Electrostatic Trapping
- Deepika Sharma, Roderick Y. H. Lim, Thomas Pfohl, and Yasin Ekinci. Part. Part. Syst. Charact. 2021, 38, 2000275
- Tuning topography and patterns of thin polymer films on structured substrates
- Konstantinos Roumpos. Inauguraldissertation der Fakultät für Mathematik und Physik 2021. DOI: 10.6094/UNIFR/194127
- Morphological transitions in langmuir films of a diblock copolymer from polyethylene glycol and poly-L-lactide
- Emna Khechine. Inaugural-Dissertation zur Erlangung des Doktorgrades der Fakultät für Chemie und Pharmazie, 2021
- High-throughput injection molding of transparent fused silica glass
- Markus Mader, Oliver Schlatter, Barbara Heck, Andreas Warmbold, Alex Dorn, Hans Zappe, Patrick Risch, Dorothea Helmer, Frederik Kotz, Bastian E. Rapp. Science 372 (2021) 182-186
- Formation of large polymer crystals from metastable solutions
- Tianyu Wu. Inauguraldissertation der Fakultät für Chemie und Pharmazie 2020, DOI: 10.6094/UNIFR/167415
- Exploring pathways to equilibrate Langmuir polymer films
- Abhijna Das, Sebastian Noack, Helmut Schlaad, Günter Reiter, Renate Reiter. Langmuir 36 (2020) 8184–8192
- Energy transport and light propagation mechanisms in organic single crystals
- Bernd Wittmann, Stephan Wiesneth, Sajedeh Motamen, Laurent Simon, Françoise Serein-Spirau, Günter Reiter, and Richard Hildner. Journal of Chemical Physics 153 (2020) 144202
- Large quantum efficiency enhancements of pristine conjugated polymer MEH-PPV by interlayer polymer diffusion
- Po-Tsun Chen, Ya-Wei Yang, Günter Reiter, Arnold C.-M. Yang. Polymer 204 (2020) 122753
- Formation of Needle-like Poly(3-hexylthiophene) Crystals from Metastable Solutions
- Tianyu Wu, Thomas Pfohl, Sivasurender Chandran, Michael Sommer and Günter Reiter. Macromolecules 53 (2020) 8303–8312
- Rheological Properties of Blends of Isotactic Polystyrene–Isotactic Poly(para-methylstyrene) Films Derived from a Comparative Dewetting Study
- Austine Amukayia Mulama, Konstantinos Roumpos, Pradipkanti Lairenjam, Andrew Oduor, Günter Reiter. Macromolecules 53 (2020) 9122–9130
- Dewetting-Induced Alignment and Ordering of Cylindrical Mesophases in Thin Block Copolymer Films
- Heng Zhang, Binghua Wang, Gang Wang, Changyu Shen, Jingbo Chen, Günter Reiter, Bin Zhang. Macromolecules 53, (2020) 9631–9640
- Estimation of the Size of Critical Secondary Nuclei of Melt-Grown Poly(l-lactide) Lamellar Crystals
- Shujing Zhang, Baohua Guo, Günter Reiter, Jun Xu. Macromolecules 53 (2020) 3482–3492
- Translating molecular relaxations in non-equilibrated polymer melts into lifting macroscopic loads
- Farzad Ramezani, Jörg Baschnagel, and Günter Reiter. Phys. Rev. Materials 4 (2020) 082601
- A new growth process for crystalline ultra-thin layers of conjugated oligomers used in field-effect transistor applications
- Sven Renkert, Sadiara Fall, Sajedeh Motamen, Thibaut Jarrosson, Françoise Serein-Spirau, Thomas Heiser, Laurent Simon, Günter Reiter, Jean-Luc Bubendorff. Applied Surface Science 539 (2021) 148024
- The memorizing capacity of polymers
- Günter Reiter. J. Chem. Phys. 152, 150901 (2020)