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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

Initial Stages of Polymer Interdiffusion Studied by Neutron Reflectometry
M. Stamm, S. Hüttenbach, G. Reiter, T. Springer. Europhys. Lett. 14, 451 (1991)
Measurements of Polymer Diffusion Over Small Distances: A Check of Reptation Arguments
G. Reiter, U. Steiner. J. Phys. (France) II 1, 659-671 (1991)
Time Regimes in Polymer Interdiffusion Determined by Marker Movement
G. Reiter, S. Hüttenbach, M. Foster, M. Stamm. Macromolecules 24, 1179 (1991)
X-ray and Neutron Reflectometry for the Investigation of Polymer Diffusion
G. Reiter, S. Hüttenbach, M. Foster, M. Stamm. Fresenius J. Anal. Chem. 341, 284-288 (1991)
Molecular-Dynamics in Perfluoro-n-Eicosane. 3. Oscillatory and Diffusive Translational Motion
T. Albrecht, R. Jäger, W. Petry, R. Steiner, G. Strobl, B. Stühn. Journal of Chemical Physics 95, 2817-2822 (1991)
Molecular-Dynamics in Perfluoro-n-Eicosane. 2. Components of Disorder
T. Albrecht, H. Elben, R. Jäger, M. Kimmig, R. Steiner, G. Strobl, B. Stühn, H. Schwickert, C. Ritter. Journal of Chemical Physics 95, 2807-2816 (1991)
Molecular-Dynamics in Perfluoro-n-Eicosane. 1. Solid-Phase Behavior and Crystal-Structures
H. Schwickert, G. Strobl, M. Kimmig. Journal of Chemical Physics 95, 2800-2806 (1991)
Mesogenic 4-Methoxyphenyl 4-Hexyloxybenzoate
W. Haase, H. Paulus, G. Strobl, W. Hotz. Acta Crystallographica C, Crystal Structure Communications 47, 2005-2006 (1991)
Ellipsometric characterisation of Langmuir monolayer of “hairy-rod” polymeres at the air-water interface
H. Motschmann, R. Reiter, R. Lawall, G. Duda, M. Stamm, G. Wegner, W. Knoll. Langmuir 7, 2743-2747 (1991)
Comparative Study of Individual and Collective Rotational Motion in Mixtures of Liquid Crystalline Side Group Polymers and Low Molecular Weight Mesogens
H. Seiberle, W. Stille and G. Strobl. Macromolecules 23, 2008 (1990)
Interdiffusion of Polymer Thin Films as Determined by Scattering Techniques
M. Stamm, D. Brautmeier, G. Reiter, M. Foster. Proceed. of the 48th ANTEC 1990 Dallas, USA on "Plastics in the Environment: Yesterday, Today and Tomorrow" 36, 825 (1990)
Characterisation of Polymer Surfaces and Interfaces by Reflectivity and Interference Techniques
M. Stamm, G. Reiter, M. Foster, H. Motschmann, S.Hüttenbach, C. Toprakcioglu. Sci. and Eng., ACS/PMSE 62, 843 (1990)
Interfacial Mixing of Polymers as Investigated by X-ray and Neutron Reflectometry
M. Stamm, G. Reiter, S. Hüttenbach, M. Foster. ACS Polymer preprints 31, 73 (1990)
X-ray Reflectometer for Study of Polymer Thin Films and Interfaces
M. Foster, M. Stamm, G. Reiter, S. Hüttenbach. Vacuum, 41, 1441-1444 (1990)
Positron Lifetime Investigations on Linear Polyethylene Compared to Branched Polyethylene
G. Reiter, P. Kindl. phys. stat. sol. (a) 118, 161-168 (1990)
Concentration-Dependence of the Flory-Huggins Interaction Parameter of a Polymer Blend as Determined by Small-Angle X-Ray-Scattering Experiments
T. Koch, G.R. Strobl. Journal of Polymer Science B - Polymer Physics 28, 343-353 (1990)
Positron Lifetime Investigations on Polymethylmethacrylate
P. Kindl, G. Reiter. In: Positron Annihilation, Ed. L. Dorikens-Vanpraet, M. Dorikens, and D. Segers, World Scientific, Singapore 1989 (p.806)
A Neutron Reflectometer for the Investigation of Solid and Liquid Interfaces
M. Stamm, G. Reiter, S. Hüttenbach. Physica B 156, 564-566 (1989)
Kinetics of Relaxation and Unmixing in Polymer Blends as Studied by X-Ray-Scattering
G. Strobl. Makromolekulare Chemie - Macromolecular Symposia 26, 413-429 (1989)
X-Ray-Scattering Study of Molecular Order in a Liquid Crystal-Side Group Polysiloxane
W. Hotz, G. Strobl. Colloid and Polymer Science 267, 889-898 (1989)
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