Martin Luther University Halle-Wittenberg

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Institut für Physik - NMR

phone: +49 (0) 345 55 28551

Betty-Heimann-Str. 7
06120 Halle (Saale)

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Upcoming P3S Webinars

The online meetings take place via Zoom [click here] and open at about 1:40 pm UTC for testing and informal chat among the participants (meeting ID: 876 8664 6314, password: 459406).

Thursday, March 18, 2021, 3 pm CET

Prof. Dr. Ali Dhinojwala

Polymer Science and Engineering, U Akron

Probing Buried Polymer Interfaces using Interface-Sensitive Nonlinear Optical Spectroscopy

Abstract:
Polymer interfaces control many properties such wetting, adsorption, adhesion, friction, and mechanical properties, and understanding interfacial interactions has remained of central importance for years. In my talk, I discuss the measurements of interfacial interactions (van der Waals and ’polar’ acid-base) by measuring shifts in hydrogen bonding peaks using interface-sensitive sum frequency generation spectroscopy (SFG). Examples will be provided on how the strength of the interfacial interactions influences polymer adsorption from solutions, segregation from polymer blends, and durability and adhesion strength of coatings and adhesives.

Dr. Torsten Gutmann

Inorganic and Physical Chemistry, TU Darmstadt

Solid-state NMR and Dynamic Nuclear Polarization - A powerful tool to study chemical modifications of cellulose based functional materials

Abstract:
The technique of Dynamic Nuclear Polarization (DNP) is introduced to significantly boost sensitivity in solid-state NMR. This enables the detection of low concentrated surface species as well as of low sensitive nuclei such as 15N in natural abundance in functionalized materials. Modified cellulose based materials that can be used in sensorics, microfluidics or optical applications are focused in the presentation.

Thursday, Apri 8, 2021, 3 pm CET

Prof. Dr. Kay Saalwächter

Institut für Physik, Martin-Luther-Univ. Halle

Hierarchical sticker and sticky chain dynamics in transient elastomers for self-healing applications

Abstract:
We study the relations between the microscopic dynamics and the  mechanical behavior of different types of transient elastomers based  upon poly(isobutylene) with sticky groups forming clusters in the nm  range, namely ionic side groups or hydrogen-bonding terminal groups. The  dynamics of the chains and of the sticky groups were studied by a  combination of dielectric spectroscopy (DS) and advanced NMR methods,  and are correlated with the rheological behavior.

Prof. Dr. Quan Chen

ChangChun CAS Institute of Applied Chemistry

Molecular Rheology of Associative Polymers

Abstract:
This presentation places a focus on the stretchability of associative polymers upon application of the fast elongational flow (with Weissenberg number much larger than one). We examined in detail how the stretchability was affected by (1) changing the number density of associative groups, (2) tuning the association energy, and (3) introducing a secondary weaker association.

Thursday, Apri 22, 2021, 3 pm CET

Prof. Dr. Liangbin Li

National Synchrotron Radiation Lab, Univ. of Science and Tech. of China, Hefei

Flow-Induced Crystallization of Polymers during Multi-Axial Deformation

Abstract:
Flow- or stretch-induced  crystallization (FIC or SIC) is believed to be mainly responsible for the excellent mechanical  properties of polymers during real service conditions. In this presentation, the FIC  behaviors of polymers (i.e. natural rubber and polyethylene) during multi-axial deformation like biaxial stretching, film blowing and  balloon blowing  will be presented with the assistance of synchrotron  radiation X-ray scatterings. Considering the phenomenon of frustrating  SIC for natural rubber during biaxial stretching, here we proposed a new model for SIC based on  the results of theoretical calculation, which decouples the free energy contributions of chain orientation from that of conformational entropy reduction.

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