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Recent Publications


Post-spin Stretch Improves Mechanical Properties, Reduces Necking, and Reverts Effects of Aging in Biomimetic Artificial Spider Silk Fibers

Gabriele Greco, Benjamin Schmuck, Fredrik G. Bäcklund, Günter Reiter and Anna Rising. ACS Applied Polymer Materials, published online

reiter-2024-05.jpgRecent biotechnological advancements in protein production and development of biomimetic spinning procedures make artificial spider silk a promising alternative to petroleum-based fibers. To enhance the competitiveness of artificial silk in terms of mechanical properties, refining the spinning techniques is imperative. One potential strategy involves the integration of post-spin stretching, known to improve fiber strength and stiffness while potentially offering additional advantages. Here, we demonstrate that post-spin stretching not only enhances the mechanical properties of artificial silk fibers but also restores a higher and more uniform alignment of the protein chains, leading to a higher fiber toughness. (more...)
 


Mechanistically Different Mechanochromophores Enable Calibration and Validation of Molecular Forces in Glassy Polymers and Elastomeric Networks

Raphael Hertel, Maximilian Raisch, Michael Walter, Günter Reiter, Michael Sommer. Angew. Chem. Int. Ed. 2024, e202409369

sommer.jpgSterically distorted donor-acceptor p‑systems, termed DA springs, can be progressively planarized under mechanical load causing a bathochromic shift of the photoluminescence (PL) spectrum. By combining theory and experiment, we here use a simple linear force calibration for two different conformational mechanochromophores to determine molecular forces in polymers from the mechanochromic shift in PL wavelength during multiple uniaxial tensile tests. Two systems are used, i) a highly entangled linear glassy polyphenylene and ii) a covalent elastomeric polydimethylsiloxane network. The mean forces estimated by this method are validated using known threshold forces for the mechanochemical ring-opening reactions of two different spiropyran force probes. The agreement between both approaches underlines that these DA springs provide the unique opportunity for the online monitoring of local molecular forces present in diverse polymer matrices.(more...)


"Printing" on Polymer Single Crystals through Microregional Heating

Tianyu Wu, Haimu Ye, Xinyi Pan, Yaning He, Jun Xu, Günter Reiter. ACS Appl. Polym. Mater. 2024, 6, 14, 7969–7977

tianyu.jpgPolymer single crystals are composed of well-ordered polymer chains and possess a characteristic symmetric shape. If one can precisely control the microregional morphology, polymer single crystals have the potential to be used as functional templates for applications like information storage or cell culture. However, with current experimental approaches, it is rather difficult to generate predictable structures of defined size within polymer single crystals. Here, we propose a research strategy based on a combination of fluorescence labeling and microregional heating by irradiation with focused red light. This approach enabled us to locally heat single crystals while simultaneously following the thereby induced changes via fluorescence imaging with a micrometer lateral resolution. We found that polymers diffused out of the heated region within a stacked single crystal and thereby produced a hole at the irradiated location. (more...)


Mechanism for the Formation of Millimeter-Long Solid Filaments by Spin Coating Dilute Solutions of a Crystallizable Polymer

Da Huang, Thorsten Hugel, and Günter Reiter. Macromolecules 2024, 57, 3696–3705

huang.jpgWe have investigated the formation of millimeter-long filaments induced by spin-coating ca. 130 °C dilute para-xylene solutions of rapidly crystallizable polyethylene chains with a contour length in the micrometer range onto ca. 80 °C mica substrates. These filaments were radially oriented and accumulated on the periphery of the substrate. Our observations can be explained by the stretching of polymers through the flow field induced by spinning the solution on a solid substrate. The corresponding loss in conformational entropy emphasized attractive interactions between polymers, which resulted in the formation of bundles and their assembly into long filaments. Caused by a Plateau–Rayleigh-type instability of a liquid coating on a solid filament and due to crystallization, these filaments were decorated with various small-scale structures. (more...

 

List of Publications

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)
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)
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