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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

Transient Inhomogenities in Polymeric Liquids and Solutions - Characterization by Static and Dynamic Light-Scattering
T. Koch, G.R. Strobl, B. Stühn. Polymer 34, 1988-1990 (1993)
Kinetics of Rotational Motion in Liquid-Crystalline Polymers
W. Stille, G. R. Strobl. Polym. Sci. (Russia) 35, 1484 (1993)
Investigation of Optical Anisotropy at Polymer Surfaces and in Thin Polymer-Films by Variable-Angle Ellipsometry
H. Kasten, G. Strobl. Fresenius Journal of Analytical Chemistry 346, 300-302 (1993)
Molecular Weight Dependence of the Rotational Diffusion Constant and the Rotational Viscosity of Nematic Side-Group Polymers
S. Götz, W. Stille, G. Strobl. Ber. Bunsenges. Phys. Chem. 97, 1315 (1993)
Structure of Thin Block-Copolymers Films Studied by X-Ray Reflectivity
R. Mutter, G. Strobl, B. Stühn. Fresenius Journal of Analytical Chemistry 346, 297-299 (1993)
Dependence of the rotational viscosity of nematic mixtures on the rotational diffusion constants of their components
G. Christoph, W. Stille and G. Strobl. J. Chem. Phys. 99, 3075 (1993)
Molecular-Dynamics in Perfluoro-n-Eicosane. 4. Oscillatory and Diffusive Rotational Motion
M. Kimmg, R. Steiner, G. Strobl, B. Stühn. Journal of Chemical Physics 99, 8105-8114 (1993)
Ellipsometric characterisation of streptavidin binding to biotin-functionalized monolayers at the air-water interface
R. Reiter, H. Motschmann, W. Knoll. Langmuir 9, 2430-2435 (1993)
Pretransitional nematic surface order in the isotropic phase of phenylcyclohexanes
S. Immerschitt, T. Koch, W. Stille and G. Strobl. J. Chem. Phys. 96, 6249 (1992)
Formation of Silver Islands on Langmuir-Blodgett Films as Investigated by X-ray Reflectometry
G. Reiter, C.Bubeck, M. Stamm. Langmuir 8, 1881 (1992)
Dewetting of Thin Polymer Films
G. Reiter. Physical Review Letters 68, 75 (1992)
Application of 15N Nuclear Reaction Technique for Hydrogen Analysis in Polymer Thin Films
D. Endisch, F. Rauch, A. Götzelmann, G. Reiter, M. Stamm. Nuclear Instruments and Methods in Physics Research B62, 513 (1992)
Use of Ellipsometry in a Study of the Surface Order in the Isotropic Phase of a Liquid Crystalline Polyacrylate
S. Immerschitt, W. Stille, and G. Strobl. Macromolecules 25, 3227 (1992)
Light-Scattering Study of Fluctuations oin Concentration, Density, and Local Anisotropy in Polystyrene Dioxane Mixtures
T. Koch, G. Strobl, B. Stühn. Macromulecules 25, 6255-6261 (1992)
Neutron-Scattering Study of Segmental Dynamics in the Disordered Regions of Partially Crystalline Polyethylene
G. Hohlweg, B. Holzer, W. Petry, G. Strobl, B. Stühn. Macromolecules 25, 6248-6254 (1992)
Ellipsometric microscopy: Imaging monomolecular surfactant layers at the air-water interface
R. Reiter, H. Motschmann, H. Orendi, A. Nemetz, W. Knoll. Langmuir 8, 1784-1788 (1992)
The Effect of Short and Long Range Interactions on the Break up and Dewetting of Thin Polymer Films
G. Reiter. Proceedings of the MRS Fall meeting 1991, Boston, USA
TOREMA - A Neutron Reflectometer at Jülich
M. Stamm, S. Hüttenbach, G. Reiter. Physica B 173, 11 (1991)
The Use of X-ray and Neutron Reflectometry for the Investigation of Polymeric Thin Films
M. Stamm, G. Reiter, K. Kunz. Physica B 173, 35 (1991)
The Interface between 2 Strongly Incompatible Polymers
S. Hüttenbach, M. Stamm, G. Reiter, M. Foster. Langmuir 7, 2438 (1991)
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