Veranstaltungen 2022
Di, 13.12.2022 15:15 Uhr (Achtung, 1h früher als üblich!)
im SR 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Christopher M. Evans
Department of Materials Science and Engineering University of Illinois, Urbana Champaign
"Incorporating dynamic covalent bonds into polymers to control viscoelasticity and molecular transport"
Dynamic covalent bonds incorporated into a polymer network can lead to materials which are capable of being recycled, dissolved back to monomer, and self-heal in response to damage. Dynamic bonds can also dramatically impact the relaxation, viscoelasticity, and transport of small molecules through a polymer. In this talk I will discuss the important roles of dynamic covalent chemistry on the fundamental properties of polymers for a range of applications.
Meeting-ID: 932 2177 9598
Passwort: 547489
Di, 25.10.2022
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. Jürgen Senker
University of Bayreuth, Department of Chemistry
"Polymer Defects in Weathered Microplastics and Self-Aggregation of Polymer Additives - Probing Minority Components by NMR Spectroscopy"
Chemical modifications and additions to polymers dramatically change the properties of the base polymers, even if these changes occur with minuscule proportions of only a few hundred ppm. Here we show, that techniques for signal enhancement like SEOP and DNP can be used to overcome the sensitivity challenge of NMR spectroscopy and allow to characterize structural aspects and identify chemical functionalities for the minority components. The lecture will discuss the implications of the self-aggregated additive objects on the polymer properties and the potential effects of abiotically degraded microplastics in environmental compartments.
Meeting-ID: 932 2177 9598
Passwort: 547489
Details
20221025_Senker.pdf
(492,8 KB) vom 17.10.2022
Di, 19.07.2022
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. Nail Fatkullin
Institute of Physics, Kazan Federal University, Russia
" The Deuteron NMR Hahn Echo Decay in Polymer Melts."
A self-consistent approximation beyond the Redfield limit and
without using the Anderson–Weiss approximation for Hahn Echo of
deuteron spins belonging to polymer chains undergoing reptation is
formulated. The dynamical heterogeneity of the polymer segments
created by the end segments, which is shown has a frequency nature,
is also taken into account . Recent experiments with polyethylene
oxide melts will be discussed.
Di, 28.06.2022
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. Zbigniew Bartczak
Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Lodz, Poland
“Deformation instabilities and lamellae fragmentation during plastic deformation of polyethylene”
The outstanding mechanical performance of semicrystalline polymers can be attributed to their unique morphology and the robust phase interconnectivity through numerous chains intersecting the amorphous-crystalline interface. Deformation of a semicrystalline polymer is a complicated process, involving all elements of their complex morphology. In this process, different micro-mechanisms are activated at various stages. Furthermore, the active mechanisms can be adjusted with advancing strain due to interactions between adjacent amorphous and crystalline layers, which are tightly connected and therefore are forced to deform jointly. These interactions can also lead to some deformation instabilities, which in turn, may effect in opening new deformation paths and/or launch alternative mechanisms previously inaccessible, and therefore may appear very important part of the deformation sequence. [...]
Details
Bartczak_2022_06_28.pdf
(487,8 KB) vom 04.05.2022
Meeting-ID: 932 2177 9598
Passwort: 547489
Di, 21.06.2022
16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Dr. Franziska Lissel
TU Dresden, Independent Research Group Leader - Functional Electronic Materials/
Leibniz-Institut für Polymerforschung Dresden e.V. (IPF)
"Triblock Copolymers- Using Nanophase Separation to Achieve Low Modulus, Elastic Deformation and Good Mobility in Polymer Semiconductors"
Polymer electronics are competitive for applications such as wearable sensors which require high mechanical functionality (e.g., elasticity), but only moderate electronic functionality (e.g., charge carrier mobility). Still, the elastic modulus of polymer semiconductors (PSCs) (0.1 - 1 GPa for typical PSCs) is orders of magnitudes away from human skin (0.1 - 10 MPa). Different pathways were explored to achieve low-modulus PSCs, e.g. non conjugated spacers [1], backbone regioregularity [2], or sidechains modifications [3], to name a few, but lowering the modulus is generally associated with a decrease in mobility.
[...]
Details
2022_06_PMSM_Lissel.pdf
(335,7 KB) vom 13.06.2022
Meeting-ID: 932 2177 9598
Passwort: 547489
Fr, 17.6.2022 - Sonderveranstaltung!
9:15 Uhr im Großen Hörsaal, Härtelstraße 16/18, 04107 Leipzig
Prof. Bernd Reif
"Aggregation kinetics and amyloid fibril structure probed by solution and MAS solid-state NMR spectroscopy"
Abstract:
Systemic antibody light chains (AL) amyloidosis is characterized by deposition of amyloid fibrils derived from a particular antibody light chain.
In this talk, I will show solution and MAS solid-state NMR experiments to characterize the aggregation of a particular patient protein. The focus is put on a human protein sequence for which adipose and heart tissue material is available from a patient. It is shown that ex vivo material allows to reproduce the amyloid fibril structure in vitro by employing a seeding procedure. MAS solid-state NMR experiments yield information on the conformation of the amyloidogenic core and allow to probe interactions with small molecules that potentially interfere with the aggregation process.
It has been shown that soluble oligomeric protein has a direct cytotoxic effect on cardiomyocytes prior to protein aggregation and organ malfunction. Removal of circulating pathogenic light chains by chemotherapy yields a drastic reduction of the concentration of biomarkers reporting on cardiac dysfunction. Using solution-state NMR spectroscopy, we follow the individual steps involved in protein misfolding at atomic resolution. We show that the natively folded protein first partially unfolds, before it converts into a high molecular weight molten globule like structure. Oligomer formation implies high local concentrations of aggregation prone regions which catalyze the subsequent conversion into amyloid fibrils. We show that the topology of the aggregated state is determined by balanced electrostatic interactions in the core of the fibril, resulting in an anti-parallel arrangement of the beta-sheets around the conserved disulfide bond.
Di, 31.05.2022 - Sonderveranstaltung online
16:15 Uhr im (online)
Dr. Rufina Alamo
FAMU-FSU College of Engineering, Department of Chemical and Biomedical Engineering, Florida State University in Tallahassee, USA
Crystallization of Precision Polyethylene-Like Materials
Abstract:
Recent studies of polymorphism, melting behavior and crystallization kinetics of polyethylenes with moieties placed at an exact equal distance along the backbone will be presented with especial focus on the crystalline properties of precision polyethylenes with halogens, acetals and esters under rapid and isothermal crystallization from the melt. All display unusual discrete inversions in the temperature coefficient of the crystallization kinetics which correlate with transitions between crystalline structures differing in packing symmetry (polymorphs), or in a step-increase in crystal thickness. The origin of the rate minima will be discussed.
Meeting-ID: 932 2177 9598
Passwort: 547489
Fr, 20.5.2022 - Sonderveranstaltung!
10:15 Uhr Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle
We try to offer the hybrid option, but cannot guarantee it!
Prof. Toshio Tada
Center for Tire Research , An NSF Industry/University Research Center
Influence of Constrained Tensile Deformation on Cavitation of Rubber Vulcanizates
Abstract
Durability of rubber compounds, such as crack resistance, is one of the essential characteristics required to tires, for sake of safety. Mechanism underlying crack propagation of rubber vulcanizates is explored in terms of void formation and growth in the rubber matrix. Extensive X-ray and dilatometry analysis revealed that the rubber matrix at the crack tip undergoes “multi-axial” constrained tensile deformation, causing the void formation.
Meeting-ID: 932 2177 9598
Passwort: 547489
Di, 17.05.2022
16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle
Prof. Christian W. Pester
Department of Chemical Engineering, Department of Chemistry, Department of Materials Science and Engineering, The Pennsylvania State University, USA
"Design of Advanced Functional Surfaces using Oxygen-tolerant Photopolymerization"
Abstract:
The covalent attachment of polymers has emerged as a powerful strategy for the preparation of multi-functional surfaces. This presentation highlights our work on surface-initiated photoinduced electron/energy transfer (PET) reversible addition–fragmentation chain transfer (RAFT) polymerization. Oxygen tolerance, mild reaction conditions, and the use of visible light make this approach user-friendly in its application for the design of patterned and functional organic thin films.