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Properties of Charged Conjugated Polymers Deposited by Electrospraying on Substrates with an Insulating Oxide Layer

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

Formation of asymmetric leaf-shaped crystals in ultrathin films of oriented polyethylene molecules resulting from high-temperature relaxation and recrystallization
Huihui Li, Duanzijing Liu, Xinyun Bu, Zhenzhen Zhou, Zhongjie Ren, Xiaoli Sun, Renate Reiter, Shouke Yan, Günter Reiter. Macromolecules 53 (2020) 346-354
Controlling phase transitions in Langmuir polymer films
Abhijna Das. Inauguraldissertation der Fakultät für Mathematik und Physik 2020. DOI: 10.6094/UNIFR/167266
Controlling Nucleation in Quasi-Two-Dimensional Langmuir Poly(L-lactide) Films through Variation of the Rate of Compression
Abhijna Das, Ahmed S. El-Tawargy, Emna Khechine, Sebastian Noack, Helmut Schlaad, Günter Reiter, and Renate Reiter. Langmuir 35 (2019) 6129-6136
Activity of the Gramicidin A Ion Channel in a Lipid Membrane with Switchable Physical Properties
Renate Reiter, Ekaterina Zaitseva, Gerhard Baaken, Ibrahim Halimeh, Jan C. Behrends, Andreas Zumbuehl. Langmuir 35 (2019) 14959-14966
Dewetting Rheology for Determining Viscoelastic Properties of Non-equilibrated Thin Polymer Films
Austine A. Mulama, Sivasurender Chandran, Konstantinos Roumpos, Andrew O. Oduor, and Günter Reiter. Macromolecules 52 (2019) 7894-7903
Relation between Charge Transport and the Number of Interconnected Lamellar Poly(3-hexylthiophene) Crystals
Binghua Wang, Jingbo Chen, Changyu Shen, Günter Reiter, Bin Zhang. Macromolecules 52 (2019) 6088-6096
Fully Isotactic Poly(p-methylstyrene): Precise Synthesis via Catalytic Polymerization and Crystallization Studies
Tianyu Wu, Luis Valencia, Thomas Pfohl, Barbara Heck, Günter Reiter, Pierre Lutz, Rolf Mülhaupt. Macromolecules 52 (2019) 4839-4846
Photoelectronic properties of composite films based on conductive polymer PIDT-BT and single-walled carbon nanotubes
Andrey N. Aleshin, Baode Zhang, Petr A. Aleshin, Vasily N. Petrov, Irina N. Trapeznikova, Günter Reiter, Janis Kleperis. SN Applied Sciences 1 (2019) 1101
Segmental Rearrangements Relax Stresses in Nonequilibrated Polymer Films
Sivasurender Chandran, Günter Reiter. ACS Macro Letters, 8, 646, (2019)
Thermodynamic Features of Perfectly Crystalline Poly(3-Hexylthiophene) Based on Flory’s Relation
Mina Alizadehaghdam, Silvia Siegenführ, Farhang Abbasi, and Günter Reiter. Journal of Polymer Science Part B: Polymer Physics 57, 431–437 (2019)
Thermodynamic Features of Perfectly Crystalline Poly(3-hexylthiophene) Revealed Through Studies of Imperfect Crystals
Mina Alizadehaghdam, Barbara Heck, Silvia Siegenführ, Farhang Abbasi, and Günter Reiter. Macromolecules 52 (2019) 2487–2494
A Structural Fibrillation Parameter from Small Angle X-ray Scattering to Quantify Pulp Refining
Jia Mao, Barbara Heck, Hatem Abushammala, Günter Reiter, and Marie-Pierre Laborie. Cellulose 26 (2019) 4265–4277
Following isothermal and non-isothermal crystallization of poly(3- hexylthiophene) thin films by UV-vis spectroscopy
Mina Alizadehaghdam, Barbara Heck, Silvia Siegenführ, Yaser AlShetwi, Fanuel M. Keheze, Sebastian Stäter, Farhang Abbasia, Günter Reiter. Polymer 210 (2020) 122959
Snails as living 3D printers: free forms for the architecture of tomorrow
Christoph Allgaier, Benjamin Felbrich, Frederik Wulle, Emna Khechine, James H. Nebelsick, Achim Menges, Günter Reiter, Renate Reiter, Armin Lechler, Alexander Verl, Karl-Heinz Wurst. In Knippers, J; Schmid, U.; Speck, T. (eds.) Biomimetics for Architecture, Birkhäuser, Basel 2019, pp 126-133. (ISBN: 978-3-0356-1791-7)
Controlling the Growth of Stacks of Correlated Lamellar Crystals of a Block Copolymer
Sumit Majumder, Renate Reiter, Jun Xu and Günter Reiter. Macromolecules 52 (2019) 9665-9671
Determination of the Critical Size of Secondary Nuclei on the Lateral Growth Front of Lamellar Polymer Crystals
Shujing Zhang, Jiarui Han, Yang Gao, Bao-Hua Guo, Günter Reiter, Jun Xu. Macromolecules 52 (2019) 7439-7447
A Nucleation Mechanism Leading to Stacking of Lamellar Crystals in Polymer Thin Films
Sumit Majumder, Purushottam Poudel, Hui Zhang, Jun Xu, Günter Reiter. Polymer International 69 (2020) 1058
Processing Pathways Decide Polymer Properties at the Molecular Level
S. Chandran, J. Baschnagel, D. Cangialosi, K. Fukao, E. Glynos, L. M. C. Janssen, M. Müller, M. Muthukumar, U. Steiner, J. Xu, S. Napolitano, and G. Reiter. Macromolecules 52 (2019) 7146-7156
Controlling the Pore Size in Conjugated Polymer Films via Crystallization-Driven Phase Separation
Shaowen Guo, Changyu Shen, Jingbo Chen, Günter Reiter, Bin Zhang. Soft Matter 15 (2019) 2981-2989
Adapted Creep Test for the Study of Non-Equilibrated Thin Polymer Films
Farzad Ramezani. Inaugural-Dissertation zur Erlangung des Doktorgrades der Fakultät für Mathematik und Physik der Albert-Ludwigs-Universität Freiburg 2019
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