Veranstaltungen 2023
Tue, 24.10.2023
16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Prof. Dr. Chris McNeill
Monash University, Melbourne, Australia
Resonant Tender X-ray Scattering of Conjugated Polymers
Semiconducting polymers are being developed for application in a wide range of optoelectronic devices including solar cells, LED and transistors. Being polymeric materials they offer advantages over traditional semiconductors including ease of processing and mechanical flexibility. Most semiconducting polymers are semicrystalline, and the way in which polymer chains pack strongly affects their optoelectronic performance. Unlike small molecule crystals whose structure can be directly solved using established crystallographic methods, semiconducting polymers are more disordered meaning that there are not enough diffraction peaks available. To squeeze more information from the diffraction peaks that are present, we have turned to resonant tender X-ray diffraction: By varying the X-ray energy across an elemental absorption edge, variations in diffraction intensity are observed that can provide additional information about molecular packing. Also known as anomalous diffraction, this technique has been applied in other fields such as protein crystallography. As many semiconducting polymers utilise sulfur as heteroatoms, we have studied resonant diffraction effects at the sulfur K-edge in the tender X-ray regime. By performing high resolution energy scans across the sulfur K-edge, we show that spectroscopic information relating to specific bonds and molecular orientation can be discerned in the resonant X-ray diffraction profiles.
Indeed, by understanding the anisotropic X-ray absorption properties of these materials we are able to interpret this data allowing us to distinguish between different crystalline polymorphs and resolve the tilting of the polymer backbone with respect to the unit cell axes. In general our work highlights how the fields of crystallography and spectroscopy can be combined to provide new insights into the molecular packing of weakly ordered soft materials.
Meeting-ID: 2731 781 6143
Passwort: bVhRTe5C?87
Tue, 17.10.2023
16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Prof. Dr. Rameshwar Adhikari
Central Department of Chemistry and Research Centre for Applied Science and Technology (RECAST), Tribhuvan University, Kathmandu, Nepal
Structure-Properties Correlations in poly(butylene adipate -co-terephthalate) Based Compostable Composites
We shed light on the structure-properties correlation of composite materials comprising a biodegradable polymer, the poly(butylene adipate-co-terephthalate) (PBAT), and some natural fibers (such as lignocelluloses, chitosan processed via different routes) and nanofillers (such as multiwalled carbon nanotubes), particularly focusing on mechanical, morphological and electrical properties as well as degradation under soil burial conditions. It was shown that the morphology and mechanical properties of the composites can be tailored over a wide range although the materials were found to be suited for low load bearing applications.
Meeting-ID: 2731 781 6143
Passwort: bVhRTe5C?87
Tue, 10.10.2023
16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Prof. Dr. Ralf B. Wehrspohn
Microstructure-based Materials Design, Martin Luther University Halle-Wittenberg
(Towards) bio-intelligent materials
The wetting behavior on 2D and 3D surfaces for e.g. polymer processing or nanostructuring is still in detail unknown and difficult to measure since inner surfaces are difficult to characterize. Similarly, hierarchically structured polymer nanostructures or metamaterials with improved mechanical properties exhibit similar problem understanding their detailed behavior.
For understanding wetting behavior as inner polymer nanostructures,
3D microscopy is of utmost importance. Since about 10 years now, 3D X-Rays Microscopy with nanometer resolution is available for
university research. With our microscopic technology, we are able
to understand for the first time the wetting kinetics and the principles of hierarchically structured polymers.
At the end of the seminar, the limits in resolution are discussed and possible ways to circumvent them are presented such as expansion
microscopy.
Meeting-ID: 2731 781 6143
Passwort: bVhRTe5C?87
Tue, 11.07.2023
4.15 pm in seminar room 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Dr. Arash Nikoubashman
Statistical Physics and Soft Matter Theory, University of Mainz
Directed assembly of polymeric nanoparticles through solvent exchange
Tailored nanoparticles are increasingly sought after for many scientific and technological applications, such as optoelectronic devices and selective catalysts. However, both research and commercialization of these materials has been impeded by the lack of suitable fabrication techniques. One promising approach for overcoming this hurdle is flash nanoprecipitation, where (soft) nanoparticles are assembled through rapid micromixing of polymers in solution with a miscible poor solvent. This continuous process allows for high yields as well as precise control over particle size and morphology. We employed multiscale simulations of this process to understand its underlying mechanisms and to efficiently explore parameter space. We first performed explicit solvent molecular dynamics (MD) simulations of a bead-spring polymer model to study the microscopic properties of the fabrication process. Then, we fed the MD data into a kinetic Monte Carlo algorithm to reach macroscopic length- and timescales. We discovered that the nanoparticle size can be reliably tuned through the initial polymer concentration and the mixing rate. Further, we were able to fabricate a wide variety of structured colloids, such as (amphiphilic) Janus and core-shell particles, when polymer blends were used in the feed stream.
Meeting-ID: 932 2177 9598
Passwort: 547489
Tue, 04.07.2023
4.15 pm in seminar room 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Prof. Dr. Seema Agarwal
Faculty of Biology, Chemistry and Earth Science, Macromolecular Chemistry, University of Bayreuth
Plastic pollution: Role of sustainable biodegradable polymers
The extreme stability of polymers has challenged society with the accumulation of plastic waste and its management worldwide. Whether biodegradable polymers can be one of the solutions to the problem of plastic waste is a question very often raised in this context. The answer is not straightforward as several aspects need to be considered regarding environmental sustainability, acceptability, and degradability in the complex natural environment. The present talk will discuss the present scenario of the environmental acceptability of biodegradable polymers and the opportunities and challenges they offer regarding solving the problem of plastic pollution and their impact on the environment.
Meeting-ID: 932 2177 9598
Passwort: 547489
Tue, 23.05.2023
4.15 pm in seminar room 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Dr. Ralm G. Ricarte
Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310
"Linear viscoelasticity of vitrimer melts"
Vitrimers are covalently cross-linked polymer networks that are insoluble in good solvent but still recyclable at elevated temperatures. These paradoxical traits are enabled by their cross-links, which engage in dynamic associative exchange reactions. Altering the chemical structure of the vitrimer cross-linker, backbone, or both modifies flow and mechanical properties. In this talk, I will discuss our efforts to experimentally and theoretically illuminate structure-viscoelasticity relationships for vitrimer melts with cross-link densities well above the gel point.
Meeting-ID: 932 2177 9598
Passwort: 547489
Tue, 02.05.2023
4.15 pm in seminar room 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Dr. Anja Kuhnhold
Theoretical physics soft group, Institute of Physics, University of Freiburg
"From cholesteric liquid crystals to nematic tactoids - an overview of the behavior of (chiral) hard rods and (im)penetrable spheres"
Model systems composed of rod-like and spherical particles can tell us a lot about various actual soft matter systems.
By changing the geometry, the interaction, and the composition of particles in such model systems, one can study a range of soft matter phenomena, from (cholesteric) liquid crystalline phases over colloidal membranes to nematic tactoids.
We study different aspects of such systems by employing computer simulations involving rod-like and spherical particles. This talk will provide an overview of some of these aspects and how they can be tackled with simulation and theory.
Meeting-ID: 932 2177 9598
Passwort: 547489
Tue, 31.01.2023 (Online Seminar!)
Prof. Dr. Olivier Lame
INSA de Lyon Department of Materials Science and Engineering
"A Coarse grained molecular dynamic model for realistic semi-crystalline structures: characterization of the amorphous phase in lamellar structures."
We use an high crystallizable coarse grained MD model to build oriented semi crystalline lamellar structure of typically 300000 beads with 1500 chains. By using artificial nucleus, we have forced the system to crystallize in a specific direction which ease mechanical testing and analyses. Moreover, we have characterized precisely the topology and structure of amorphous phase to try to better understand the mechanical properties.
Meeting-ID: 932 2177 9598
Passwort: 547489
4.15 pm in seminar room 1.27 Von-Danckelmann-Platz 4, 06120 Halle
This is an online seminar, but audience is encouraged to come to the seminar room for the live transmission and Q+A session.
Tue, 17.01.2023
4.15 pm in seminar room 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Prof. Dr. Andreas Walther
Life-Like Materials and Systems, Department of Chemistry, University of Mainz
"Metabolic DNA Systems Inspired from Life: Protocells and Systems with Lifecycles"
Living self-organizing systems operate far-from-equilibrium and display energy-dependent adaptive functionalities. They can serve as an inspiration to promote complexity and life-like functions in soft matter systems, which include for instance to pre-organize temporal behavior or install mechanisms for complex adaptative behavior. Along these lines, I will discuss two avenues towards autonomous and adaptive DNA active matter systems with simplistic metabolic reaction networks inside. On the one hand, I will discuss the formation of DNA-based protocell architectures with the ability to house abiotic catalysts driving downstream morphological adaptations. On the other hand, I will discuss the use of ATP as a chemical fuel to drive chemically fueled out-of-equilibrium systems using activation/deactivation networks. The latter allows to program self-assemblies and materials with lifetimes and programmable steady state dynamics.
Review: A. Walther, “From Responsive to Adaptive and Interactive Materials and Materials Systems: A Roadmap” Adv. Mater. 1905111 (2020).
Meeting-ID: 932 2177 9598
Passwort: 547489
Tue, 10.01.2023 3.15 pm (Please note: 1h earlier than usual and in SR 1.03 in VDP3)
in SR 1.03 Von-Danckelmann-Platz 3, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Aakash Sharma
Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH
"Correlating the properties and structure of semicrystalline polymers: Case of regenerated cellulose fibers."
Structure property relations in semicrystalline fibers is a daunting problem due to the complex microstructure ordered over multiple length scales. I will talk about developing simple tools and methodologies for capturing the differences in the structure of regenerated cellulose fibers manufactured using Lyocell and Viscose processes. The relevant microstructural features are related to the mechanical properties of fibers and are responsible for their counterintuitive viscoelastic response.
Meeting-ID: 932 2177 9598
Passwort: 547489