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Die, 08.07.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

Prof. Dr. André Gröschel

Universität Bayreuth

Polymer cubosomes: From degradable delivery platforms to hybrid materials for batteries

Polymer cubosomes are a relatively new class of self-assembled microparticles of block copolymers that are open porous, have large interfacial area, and carry functional groups on surface and inside the cubosome wall. In this presentation, I will give a brief overview of recent discoveries in this field and summarize also our efforts in designing polymer cubosomes with controlled shape, dimension, and chemistry. Currently, we focus on the synthesis of functional cubosomes, develop routes for their formation, and explore diverse applications including degradable mesoporous particles for agrochemistry, templating of high surface area materials, and components for batteries.

Die, 01.07.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Holger Frauenrath

EPFL, Lausanne (Schweiz)

Supramolecular Modification of High-Molar-Mass Sustainable Polymers

The plastic waste crisis has driven interest in sustainable polymers, but these alternatives often fall short in processing and performance. Our lab developed a strategy to modify high-molar-mass polymers using end groups that co-assemble with low-molar-mass additives via multivalent hydrogen bonding. This creates bio-inspired nanofibrillar structures that enhance melt strength, extensibility, and crystallization. The approach improves both processing and solid-state properties, is broadly applicable, and scalable—offering new potential for sustainable plastic alternatives.

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Die, 24.06.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Wolfgang Parak

Universität Hamburg

Polymers and nanoparticles combined for delivery

Polymers, (inorganic) nanoparticles, and biological molecules can be combined to multifunctional units. Two points will be addressed in particular. First, by integrating nanoparticles in biodegradable polymer matrices the size of the resulting particles can be designed to vary over time. Consequences for endo- and exocytosis will be discussed. Second, polymers can be used for the encapsulation of enzymes. In this way transport of the enzymes into cells is possible via endocytosis. Applications of such internalized enzymes will be discussed.

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Meeting-Kennnummer: 2794 288 6429
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Die, 17.06.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

Prof. Dr. Holger Frey

Johannes Gutenberg-Universität Mainz

Isomerization of poly(ethylene glycol) to rPEG: Non-immunogenic, biocompatible and non-crystalline polyethers

Polyethylene glycol (PEG) is the gold standard in pharmaceutical and nanomedicine applications based on its chemical inertness, biocompatibility, and unique stealth properties. PEGylation, the conjugation of poly(ethylene glycol) (PEG) to bioactive peptide drugs or nanocarriers, is a key strategy in nanomedicine. However, recent studies have demonstrated that PEGylated therapeutics may induce severe side effects, linked to the formation of anti-PEG antibodies. This can result in complement-activated pseudo allergic reactions and accelerated blood clearance.

We introduce the randomized PEG (rPEG) technology designed to strongly reduce the antigenicity of PEG while preserving its pharmaceutical core benefits. This conceptually novel approach is based on an ideally random introduction of hydrophilic side chains along the PEG backbone via copolymerization. The rPEG strategy also gives access to non-crystalline PEG-like materials for a broad range of biomedical materials. The approach can rely on existing PEG technology at every stage, allowing for the use of established GMP manufacturing processes and supply chains. rPEG is conveniently copolymerized with lactide to PLA-based materials with elastic properties for biomedical application. In addition, rPEG leads to interesting Li-ion conducting structures.

Die, 10.06.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Philipp Seib

Friedrich-Schiller-Universität Jena

The Pharma-Silk-ceutics Paradigm

Silk is emerging as a valuable biopolymer for biomedical applications because of its unique and highly versatile structure and its robust clinical track record in human medicine. Silk can be processed into many material formats, including physically and chemically cross-linked hydrogels, nanoparticles and scaffolds that have almost limitless applications ranging from tissue engineering to biomedical imaging and sensing. This presentation provides a background on silk and will cover drug and stem cell delivery using selected silk formats.

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Die, 03.06.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Dr. Andreas Klingler

Leibniz-Institut für Verbundwerkstoffe GmbH, Kaiserslautern

Thermo-optical insights into the thermo-mechanical behaviour of dynamic polymer networks

Vitrimers, or more generally dynamic polymer networks, can reversibly change their phase state from a viscoelastic network structure with eternal character to a flowable state. This often temperature-controlled property transition is of particular interest, as it imparts certain reshaping and repair capabilities to these materials despite their covalent network bonds. However, the clarification and classification of the necessarily occurring phase transition from a viscoelastic solid to a flowable state due to dynamic covalent bond exchange requires further attention, as a correspondingly characteristic anomaly remains hidden in classical susceptibilities, such as the specific heat capacity.

In this talk, the phase transition behaviour of dynamic polymer networks will be first discussed from the perspective of dynamic thermal volume expansion. Since this property directly couples to the anharmonic molecular interaction potential, it is particularly suitable for studying solid-liquid phase and glass transitions. The rather new method of temperature-modulated optical refractometry (TMOR) used for this purpose provides simultaneously indirect insights into another key indicator for phase transitions: the shear relaxation behaviour.

Using selected model vitrimer systems, this coupled perspective of dynamic thermal volume expansion and shear relaxation will be discussed with regard to the property profile and the phase transition behaviour of dynamic polymer networks.

In Zusammenarbeit mit AgriPoly II

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Die, 27.05.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Birgit Strodel

Heinrich-Heine-Universität Düsseldorf und Forschungszentrum Jülich GmbH

Simulating Peptide Polymerization and PET Depolymerization

In my research group, we utilize simulation techniques covering different length and time scales —including atomistic classical molecular dynamics (MD) simulations, coarse-grained models, and QM/MM simulations—to explore the self-assembly of peptides and the breakdown of polyethylene terephthalate (PET). This talk will demonstrate how all-atom MD simulations uncover the aggregation tendencies of peptides, aiding in the design of peptides with tailored aggregation properties. For PET, I will showcase how MD simulations examine the adsorption of PET-hydrolyzing enzymes on amorphous and crystalline surfaces, highlighting key residues involved in adsorption and subsequent PET interaction within the active site. Our findings, confirmed by follow-up mutation studies, suggest alternative amino acids to enhance productive PET adsorption.

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Die, 06.05.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Laura Hartmann

Universität Freiburg

Sequence-defined glycopolymers for biomedical applications

Carbohydrates are an important part of our nutrition, they are used as materials e.g., cellulose or chitin, but they are also highly relevant in mediating various biological interactions, for example in cell-cell communication, immune responses and tumor growth. From a chemical point-of-view, carbohydrates are a highly diverse class of biomacromolecules using a great number of different building blocks that are assembled into linear and branched structures, oligomers, polymers and glycoconjugates. Intentionally reducing this complexity while maintaining the biological activity is achieved for so-called multivalent glycomimetics via the attachment of smaller glycan fragments onto synthetic scaffolds.

We have previously introduced sequence-defined glycopolymers as multivalent glycomimetics that can be precisely varied in terms of their scaffold structure, composition as well as number and kind of glycan fragment attached, parameters known to affect ligand properties such as avidity and binding specificity. In order to mimic the structural diversity of carbohydrates, these glycomacromolecules can then be used again as building blocks to create more complex glycomimetic structures and materials, e.g., through conjugation onto nanoparticles or proteins. The lecture will present the bottom-up synthesis of such glycopolymers and glycomimetic materials and will discuss their potential biomedical applications for example in inhibiting viral and bacterial infections.

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Die, 29.04.2025

16:15 Uhr im Seminarraum 5.10 Von-Seckendorff-Platz 1, 06120 Halle

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Dr. Ceren Kimna

Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH)

Advanced Performance Evaluation Tools for Nanoparticles in Drug Delivery

A major challenge in the development of nanoparticles for targeted drug delivery is the  lack of high-resolution tools to track their whole-body biodistribution with sufficient  sensitivity. Conventional methods primarily detect nanoparticles that accumulate at  high concentrations in major organs, overlooking promising formulations and limiting the  rational design of advanced delivery systems. Critically, low-resolution techniques also  fail to detect minor off-target populations—one of the leading causes of failure in clinical  translation.

In this talk, I will introduce SCP-nano, a high-sensitivity pipeline capable of detecting  nanocarriers—including lipid nanoparticles, liposomes, and polyplexes—down to  0.0005 mg mRNA/kg in mice. This approach enables an unbiased, quantitative  assessment of nanoparticle distribution and protein expression in wild-type animals,  providing precise insights into tissue- and cell-specific targeting. I will discuss how  integrating whole-body biodistribution data with nanoparticle design can enhance  precision drug delivery, reduce the need for exhaustive animal use, and accelerate  clinical translation timelines.

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Die, 22.04.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Ranjita Bose

Reichsuniversität Groningen (Niederlande)

Chemical vapor deposition of polymers for sustainable, biomedical and energy applications

Chemical vapor deposition (CVD) is a well-known technique for the synthesis of inorganic coatings and thin films. Milder variants, such as initiated CVD (iCVD) and oxidative CVD (oCVD), enable the synthesis of organic polymers. In these processes, a monomer and an initiator or oxidant are introduced into a vacuum reactor in the vapor phase, leading to a solvent-free, one-step, surface polymerization. These techniques deposit polymer films on delicate or porous substrates, ensuring high coating conformality.

We have used iCVD to develop materials with tunable and gradient mechanical stiffness. Bifunctional monomers like allyl methacrylate enable thermal radical initiation while preserving one functionality for UV crosslinking, creating stiffness gradients. This makes the materials suitable for implantable scaffolds requiring tunable mechanical properties. We also explore sustainable applications such as using bio-based monomers and recyclable adhesives.

Additionally, we synthesized polypyrrole using oCVD, integrating polymer synthesis, doping, and film formation in a single step. By optimizing deposition temperature, reactor pressure, and oxidant-to-monomer ratio, we achieved homogeneous polypyrrole films high conductivity of 180 S cm⁻¹ for a solvent-free method. These polymers were applied to sensors and energy storage. For piezoresistive strain sensors, polypyrrole was coated onto flexible, porous substrates like electrospun fiber mats, phase-separated hydrogel membranes, and 3D-printed lattices, allowing tunable mechanical and electrical properties. Results on strain sensing behavior, gauge factors, and cyclic stability will be presented. For electrochemical energy storage, polypyrrole was coated on a carbon fiber mat and characterized via cyclic voltammetry, galvanostatic charge-discharge, and thermal stability tests.

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Die, 08.04.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Dieter Jendrossek

Universität Stuttgart

Enzymatic cleavage of the carbon backbone in natural rubber and chemosynthetic hydrocarbon polymers

Natural rubber [poly(cis-1,4-isoprene)] is produced in annual quantities of ≈107 tons by cultivating the rubber tree (Hevea brasiliensis) by more than 100 years. The material – after chemical modification (vulcanization) – is used for numerous purposes and is present e. g. in tires, sealings, rubber clothes, latex gloves, condoms and many other items. As a natural material, rubber is biodegradable to water and carbon dioxide. Biodegradation of polyisoprene is initiated by microbial rubber oxygenases that oxidatively cleave the polyisoprene C=C-bonds yielding low molecular products. I will describe the properties of rubber oxygenases at the example of rubber oxygenase A (RoxA). In the second part, I will comment on the persuasiveness of the rapidly expanding research field of biodegradation of polyethylene (PE) and related hydrocarbon polymers (PP, PVC).

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Mon, 17.02.2025 - Sondertermin

11:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Antonia Statt

University of Illinois at Urbana-Champaign (USA)

Computational Design and Simulations of Soft Matter: From Molecular Insights to Functional Materials

This talk will first focus on the molecular inverse design of sequence-defined macromolecules for complex self-assembled disordered large-scale aggregates. By combining large-scale molecular dynamics simulations of simple models and machine learning, we identify monomer sequences that enable the design of precise target morphologies, such as drug delivery vesicles or micelles. The second topic addresses the morphology of hybrid lipid block-copolymer bilayers, offering new insights for the design of artificial membranes, transmembrane proteins, and interactions of nanoplastics with membranes.

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Die, 21.01.2025

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Konrad Tiefenbacher

Universität Basel

Catalysis inside a supramolecular capsule

My group is interested in exploring catalysis inside supramolecular containers. Our main focus has been the hexameric resorcin[4]arene capsule, originally reported by the Atwood group.1 It has served us as a reliable catalyst for a variety of acid-catalyzed cationic reactions ranging from simple acetal hydrolysis to more complex iminium catalysis and terpene cyclizations. Investigations revealed that related molecular capsules are not competent in these reactions. The most recent results concerning terpene cyclizations will be presented.2,3 Furthermore, very recent published, as well as unpublished, results concerning stereoselective glycosylations inside the hexameric resorcin[4]arene capsule will be discussed.4 A unusual proton wire mechanism is likely at work. developed.

1.    L. R. MacGillivray, J. L. Atwood Nature 1997, 389, 469.
2.    L.-D. Syntrivanis, I. Némethová, D. Schmid, S. Levi, A. Prescimone, F. Bissegger, D. T. Major, K. Tiefenbacher J. Am. Chem. Soc. 2020, 142, 5894.
3.     I. Némethová, D. Schmid, K. Tiefenbacher Angew. Chem. Int. Ed. 2023, e202218625.
4.     T-R. Li, F. Huck, GM. Piccini, K. Tiefenbacher Nat. Chem. 2022, 14, 985.

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Di, 07.01.2025 - Abgesagt

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Dr. Chien-Hua Tu

University of Pennsylvania, USA

(Non-)Equilibrium polymer chain behaviors in bulk and under nanoconfinement by dielectric spectroscopy

Dielectric spectroscopy (DS) alongside various microscopy techniques (e.g., AFM, SEM) has been used to study (non-)equilibrium polymer dynamics in bulk and under nanoconfinement. I will show recent findings to uncover the coupling-decoupling dynamics between slow main-chain backbone motions and fast side-group sticker motions across the glass transition temperature in an upcycled associating polymer, and demonstrate novel insights into the polymer imbibition within nanopores via self-developed nanofluidic DS technique, so called in situ nanodielectric spectroscopy (nDS). The critical role of chain adsorption during polymer imbibition has been elucidated.

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Mon, 16.12.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Stefan Schiller

Goethe-Universität Frankfurt am Main

Proteins as precision macromolecules in the design of supramolecular architectures and adaptive materials for applications ranging from life-sciences to biomedical “soft robotics”

Biomimetic approaches provide multifunctional solutions in life-sciences and technical applications. Biomacromolecules, especially proteins, constitute high-performance materials, such as spider silk, mussel foot proteins, elastin, collagen and resilin, providing impressive functions throughout nature. Combining properties from elastin and resilin, the almost perfect elastic material in grasshopper joints, endow biomaterials with long-lasting elastic properties and strength. The grasshopper joint hybrid-protein resilin exhibits almost perfect elasticity with the highest resilience (>98%) of any known material^[1], outperforming known man-made materials.

We mimic these proteins by redesigning partial sequences of them, designing peptide-repeating units enabling the formation of e.g. block-domain biomacromolecules similar to block-copolymers. The biotechnological productions of these biomacromolecules allows for their scalable and sustainable production. The precise molecular design/composition of these repetitive protein-macromolecules in combination with controlled amphiphilicity, can also provide specific properties via the design of hydrophilic and hydrophobic domains facilitating the constitution of supramolecular architectures. These domains are mainly composed of repetitive sequences of matrix-protein partial sequences based on elastin-like protein (ELP) motives.^[2] They do not only allow for controlled amphiphilic properties, but also provide stimulus-responsive changes of molecular interactions allowing for the formation of adjustable supramolecular architectures^[3]. Novel programmed interaction schemes with different biomolecules^[4] and protocellular synthesis platforms/artificial cells, are shown^[5]. Furthermore, we expand the range of synthetic macromolecules and natural or modified biomacromolecules to imitate tissues and muscular systems. The design of artificial muscles, exerting rhythmic autonomous movements via nonequilibrium states driven by chemically fueled pH oscillation reactions, is demonstrated. The results also show how directional movements can be independently triggered by changes in pH and temperature including a selective on-switch and a combination of nonequilibrium states enabling “learning and oblivion”-like material effects. This paves the road for the next generation of autonomous materials in pharmacy, soft robotics and living matter.

In sum the presented precision biomacromolecules provide advanced supramolecular architectures for important applications in various disciplines using adaptive materials towards smart soft robotics and tissue mimicry, pharmacy and medicine.

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Die, 03.12.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Dr. Felix Löffler

Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Potsdam

Additive chemical nanomanufacturing

3D printing technologies have revolutionized manufacturing, enabling highly customized polymer structures. Building on this, we aim to extend such customization to chemical synthesis. We have developed a laser-based additive polymer printing technology, incorporating various chemical building blocks and post-synthesis chemical modifications. This technology enables flexible parallel chemical synthesis, surface functionalization, and biomedical screening applications [1, 2]. Using our platform, we achieve targeted material synthesis, such as defined metal oxide and perovskite nanoparticles [3, 4], as well as fluorescent carbon nanodots [5]. This additive chemical nanomanufacturing process opens pathways for designing nanomaterials and functional nanodevices, including those for anti-counterfeiting [6].

[1] Adv Mater 2022, 34, 2108493
[2] Adv Mater 2022, 34, 2200359
[3] Nat Commun 2021, 12, 3224
[4] Adv Mater 2024, 2409592
[5] Nat Nanotechnol 2023, 18, 1027–1035
[6] Nat Commun 2024, 15, 1040

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Die, 26.11.2024 - Abgesagt

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. André Gröschel

Universität Bayreuth

Polymer cubosomes: From degradable delivery platforms to hybrid materials for batteries

Polymer cubosomes are a relatively new class of self-assembled microparticles of block copolymers that are open porous, have large interfacial area, and carry functional groups on surface and inside the cubosome wall. In this presentation, I will give a brief overview of recent discoveries in this field and summarize also our efforts in designing polymer cubosomes with controlled shape, dimension, and chemistry. Currently, we focus on the synthesis of functional cubosomes, develop routes for their formation, and explore diverse applications including degradable mesoporous particles for agrochemistry, templating of high surface area materials, and components for batteries.

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Die, 19.11.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Markus Retsch

Universität Bayreuth

Thermal transport and heat management in self-assembled materials

Thermal transport can be significantly influenced by the presence of nano- and mesostructures and the interfaces that exist in such materials. This structuring can be employed to realize super-insulation properties as well as efficient heat spreading. Consequently, nanoscale thermal transport has attracted a lot of research interest for the past 20 years. Furthermore, (colloidal) mesostructures play a pivotal role in light-matter interaction, covering a broad spectral range from ultra-violet to mid-infrared. Thus, solar radiance scattering and thermal radiation emission can be tuned towards passive radiative daytime cooling.

In this presentation, I will provide an overview of heat transport and heat management in mesostructured materials. Based on anisotropically structured materials on different length scales and dimensionalities I will highlight the vast possibilities to control the temperature distribution for various applications. Order and disorder further contribute to thermal transport pathways and scattering of light. Colloidal mixtures of distinct compositions are well-suited model systems to systematically unravel their role in heat management. Finally, we have a strong interest in materials with a gradient structure. I will demonstrate various pathways to access gradually structured materials and how they can be employed for optical engineering and switchable temperature gradients.

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Die, 12.11.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Dr. Friederike Adams

Universität Stuttgart

Unlocking the Potential of Yttrium Catalysis: Functional Copolymers for Advanced Applications

Due to their impressive diversity, the application horizon of thermoplastics is extending far beyond the use as ordinary consumer goods. With the shift from commodity plastics to polymers used in high-tech applications, the precise tuning and modification of these materials is a key requirement. Therefore, the optimization of polymerization catalysts plays a significant role in modern polymer chemistry to efficiently produce different polymer architectures and microstructures for fine-tuning of material properties. Well-investigated yttrium complexes can act as highly active catalysts in two different coordination polymerization types: Ring-opening polymerization (ROP) of lactones and group-transfer polymerization (GTP) of Michael-type vinyl monomers. Modifications of the complexes were carried out to improve catalytic activity and enable the synthesis of functional block copolymers with diverse end-groups. The development of these new polymers addresses several key areas of modern polymer chemistry, including biobased materials, stimuli-responsive properties, and amphiphilic polymers for drug and nucleic acid delivery applications.

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Die, 29.10.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Christian Laforsch

Universität Bayreuth

Microplastics in the Environment

The ubiquitous contamination of the environment with microplastics, the associated risks to ecosystems and ultimately to human health has recently attracted a great deal of public and scientific attention. Harmful effects of microplastics on various organisms have been shown related to the ingestion of microplastic particles. However, microplastic is a hypernym of a plethora of different polymers, each having its own distinct physical and chemical properties. Hence, no general statements can be made about the effects of microplastics per se. This is even more pronounced since microplastic particles occurring in nature exhibit various chemical and physical properties. The CRC initiative on microplastics (SFB1357) aims therefore to gain a fundamental understanding of the processes and mechanisms that cause biological effects of MP in limnic and terrestrial ecosystems, that influence migration of the MP particles within and between environmental compartments and that cause the formation of MP from macroscopic plastics - each depending on the physical and chemical properties of the plastics. These findings will provide a scientifically sound basis for the evaluation of the environmental risks of MP and to develop new environmentally friendly plastics in the sense of sustainable polymer chemistry.

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Die, 22.10.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Johannes Brendel

Universität Bayreuth

Tailored design of reactive polymers and nanostructures

Nature presents numerous examples for responsive structures, which react to subtle changes in their environment. In our group, various functional monomers and polymers are synthesized which react selectively to specific stimuli such as an oxidative environment or changes in pH. In the latter case, we realized amino-based polymers, which are selectively protonated in the biological most interesting range of pH 5-8. In another example, we utilize thioether groups to trigger a time-delayed release and degradation under oxidative conditions.

Another focus of our research is the controlled assembly of these functional polymers into nanostructures of specific shapes. Therefore, we investigate approaches such as poly­meri­zation in­duced self-assembly (PISA) or directed supramolecular interactions to guide the assembly of the functional polymer building blocks into different nanostructures. In the latter case, directing hydrogen bonds are employed to drive the assembly of funcionalized polymers into supramolecular bottlebrush-like fibres. The assembly follows a nucleation-growth mechanism which allows to tune the length of the fibers.

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Di, 15.10.2024 - Abgesagt

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Stefan Naumann

Universität Freiburg

Borane Catalysts for the Preparation of (Isotactic) Polyethers

Research in our group aims at improving the way polyethers, such as poly(propylene oxide) (PPO), are made. This work concerns aspects such as dramatically expanding the achievable molar masses,[1] designing organocatalysts[2] or using cyclic carbonates as feedstock for the polyether preparation.[3] Here, we present the first metal-free strategy to prepare isotactic-enriched aliphatic polyethers, using racemic monomer feed of, i.e., propylene oxide (PO).[4] The corresponding organocatalysts are prepared in a simple two-step route, joining two borane functionalities via a chiral backbone derived from well-available 1,1’-bi-2-naphthol (BINOL). In tandem with organobases, these chiral diboranes deliver isotactic diad contents of up to 92% alongside well-defined and high molar masses (1.1 < ÐM < 1.3, Mn > 100 000 g/mol). Notably, it is also possible to exploit the inherent functional group tolerance of boranes to grow isotactic-enriched sequences of PPO on aliphatic polyester-type initiators (polycaprolactone, polylactide), thus enabling the incorporation of stereocontrolled polyether blocks in more complex polymer architectures. It is expected that this ability will greatly benefit the preparation of polyether-containing additives. The BINOL-type backbones can be readily modified,[5] suggesting further potential as a platform from which optimized diborane catalysts can be developed.

[1] P. Walther, A. Krauss, S. Naumann, Angew. Chem. Int. Ed. 2019, 58, 10737.
[2] S. Naumann, A. W. Thomas, A. P. Dove, Angew. Chem. Int. Ed. 2015, 54, 9550.
[3] N. von Seggern, T. Schindler, S. Naumann, Biomacromolecules 2020, 21, 2661.
[4] A. Sirin-Sariaslan, S. Naumann, Chem. Sci. 2022, 13, 10939.
[5] A. Sirin-Sariaslan, S. Naumann, Chem. Commun. 2023, 59, 11069.

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Do, 01.08.2024 - Sondertermin

11:00 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Jun Xu

Department of Chemical Engineering, Tsinghua University (China)

Study on Crystal Nucleation of Polymers and Molecular Design of Environmentally Benign Polymers

Determining the size of critical nuclei of crystals is key to understanding the nucleation mechanism and testing the nucleation theories. However, it has been a great challenge from both experimental and theoretical perspectives. We have proposed a method to determine the size of critical nuclei in polymer lamellar crystals based on the probability of selecting crystallizable units on the chains of random copolymers. The sizes of critical secondary nuclei of poly(butylene succinate) and poly(L-lactide)/poly(D-lactide) stereo-complex have been obtained, which show that a critical secondary nucleus consists of multiple chain stems rather than one stem. The results contest the classical Lauritzen-Hoffman theory. Furthermore, we show that the sizes of critical secondary nuclei, isothermally crystallized from dilute solution, do not vary with supersaturation, which contradicts with the common view.

In the second part, I will show our research on fundamental research and industrial applications of biodegradable polyesters synthesized form diacids and diols. Via molecular design adopting dynamic covalent bonds, we synthesized a series of self-healable and recyclable polyurethanes, which are finding applications in biomedical fields.

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Di, 25.06.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Pieter Lemstra

Plempolco B.V. (The Netherlands)

Processing of ultrahigh-molecular-weight polyethylene reactor powders

Ultra-high-molecular-weight polyethylene, UHMW-PE, could become an interesting engineering plastic in view of the very beneficial properties like toughness, chemical resistance and notably the very high abrasion resistance, in fact superior amongst all (thermo)plastics. But the major problem is the processability via standard processing routes like injection-molding and extrusion is not possible due to the very high molar mass, >3 MDa. The melt-viscosity scaling with exponent 3.4 is prohibitively high, preventing any melt-flow.
UHMW-PE is processed via compression-moulding and/or ram-extrusion (‘hammering’ UHMW-PE through a heated tube into rods) and subsequently machined into parts. Consequently, UHMW-PE is currently only some 0,2% of the total PE market. The melt-viscosity in polymer systems is related to the presence of a physical network of entangled polymer chains and chain mobility is restricted to reptative motions as coined by De Gennes [1]. With an increasing number of entanglements per chain molecule the viscosity increases and hence the flowability of the molten polymer reduces and in the case of UHMWPE the well-known melt-index, MFI, an industrial measure of flowability, is close to zero, no flow.
The question is could removal of entanglements prior to processing (radically) improve flow hence processability? Past and ongoing research on this issue will be presented.
[1] P.G. De Gennes, Scaling concepts in polymer physics, Cornell University Press (1979)

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Di, 18.06.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Pol Besenius

Johannes Gutenberg University Mainz

Kinetic Pathways in the Supramolecular Polymerisation of Multidomain Polymer-Peptide Conjugates and Printable Hydrogels

Spatial and temporal control are critical properties to advance and optimize functional macromolecular materials in  order to mimic key features of living systems. In my contribution, I will first discuss our methodology in developing  non-equilibrium states for thermoresponsive supramolecular polymers and hydrogels. I will focus on peptide supramolecular amphiphiles using peptide-polymer conjugates or functionalized metallo-amphiphile scaffolds.[1-3] By  varying experimental conditions, sample preparation protocols or the use various external stimuli the supramolecular  polymerization is biased and controlled with respect to the morphology of the resulting structures. Charge regulated  ß–sheet self-assembly of alternating hydrophilic and hydrophobic amino acids is used in order to couple pH-stimuli to  redox-switchable properties. We have studied the pathway complexity in these supramolecular systems involving the  occurrence of metastable and kinetically trapped states, which are key in manipulating assembly protocols in view of  preparing materials systems integrating mechanical, optical or biological function.4 The design of kinetically controlled  systems has the potential to produce variable structures from the same starting material, expanding on the possibilities  and applications of purely thermodynamically controlled supramolecular polymerisations. In the second part I present  our methodology to prepare supramolecular networks which show fast stress relaxation combined with a second  physical network that can be transformed into a chemical network by applying an external photo-trigger. The  interpenetrating network shows improved shape fidelity and supports cell proliferation to allow successful applications  as bio-inks and printable cell-laden materials.[5]

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Di, 11.06.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Dennis Kurzbach

University of Vienna (Austria)

Biomolecular phase transitions by non-equilibrium NMR and dissolution DNP

Contemporarily, the physical chemistry of phase transitions witnesses a lively renaissance in a novel, biomolecular context. The functional importance of such conversion has become increasingly evident, e.g., in liquid-liquid phase separation (LLPS) of intrinsically disordered proteins and biomineral precursors. To characterize and understand these complex events, new experimental methods are necessary to shed light on the atomistic configuration of biomacromolecules during their transitions. A challenge that innovative magnetic resonance approaches can meet.

In this contribution, we suggest an unconventional approach to this challenge based on integrating hyperpolarization by dissolution dynamic nuclear polarization (d-DNP). By integrating d-DNP into existing structural biology methodological frameworks, we show that it is possible to characterize phase transitions involved in non-classical biomineralization monitored at atomistic detail by real-time NMR on timescales ranging from milliseconds to hours. While the established giants, XRD, EM, MD, and conventional solid- and liquid-state NMR are well fit to characterize the stable starting materials and final solids, d-DNP can draw the connection between them, allowing us to rationalize these important processes.

We demonstrate the potential using bio-silica precipitation via designer peptides with a functional RRIL motif thereby exploiting several recent developments: hybrid hydraulic/pneumatic injection systems(1) for controlled initiation of the precipitation processes, hyperpolarization protocols for various mineral salts (phosphates, silicates)(2), multiplexed detection schemes for comprehensive process monitoring,(3) and integration with computational techniques to obtain high-resolution models.(4)

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Di, 04.06.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Arash Nikoubashman

Leibniz-Institut für Polymerforschung Dresden and Technical University Dresden, Germany

Plastic life: What polymer physics can teach us about disordered proteins

The discovery of intrinsically disordered proteins (IDPs) has heralded a paradigm shift in molecular biology away from the principle of ”form follows function”. These IDPs can form biomolecular condensates that fulfill numerous functions in living cells, e.g., signal transduction, stress response and controlled reactions. Due to the conceptual similarities between IDPs and classical polymers, physics-based theories and computer simulations can help to understand, predict and engineer the static and dynamic properties of naturally occurring and synthetic IDPs. In this talk, I will present selected insights we have gained from coarse-grained molecular simulations, and discuss the intricacies and limitations of the underlying models. Key findings include that IDPs inherently exhibit heterogeneous interactions that are weak and distributed along the chain contour, and that IDPs collapse at the condensate-water interface and are tangentially oriented. Further, we discovered that the phase behavior and materials properties of condensates can be deducted with great accuracy from the conformations of single IDP chains in solution.

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Di, 14.05.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Stephen Schrettl

Technical University of Munich

Supramolecular Assembly for Dynamic and Responsive Polymer Systems

An assembly of monomers that feature dynamic non-covalent interactions furnishes supramolecular materials. The fact that external stimuli can modulate the strength of the interactions may lead to a temporary disassembly, which impart the materials with useful adaptive functionalities and is of interest for a cyclic materials use. In this presentation, supramolecular polymers are introduced that combine responsive characteristics with mechanical strengths akin to those of conventional plastics. By combining different building blocks that possess distinct mechanical properties, we can create materials that are strong, stiff, and tough (Figure 1). The ability to combine building blocks in any ratio allows to prepare objects with a spatially modulated mechanical behavior, effectively mimicking the anisotropic properties of more complex natural materials. Additionally, this presentation will also discuss supramolecular strategies in the development of nanoparticle composites and introduce advanced materials that generate specific optical responses when subjected to mechanical stress.

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Di, 30.04.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Jun.-Prof. Dr. Valerian Hirschberg

Clausthal University of Technology

Synthesis, rheology and constitutive modelling of complex polymer model systems

Understanding the effect of branching on the melt rheological properties in shear and elongation is of fundamental interest since the dawn of polymer science and allows to engineer material properties, with the classical example for Polyethylene of HDPE and LDPE. Besides the number and the molecular weight of the arms, the exact location of the branching points, i.e., the exact architecture of the polymer (its topology) is key to control shear and extensional rheological properties.

Continuing the pom-pom story from a purely theoretical approach, about twenty low-disperse, polystyrene samples with a pom-pom topology were synthesized with optimized synthetic routes via a combination of anionic polymerization and grafting onto, in the scale of up to 300 g per model system. The molecular parameters of the pom-poms such as molecular weight of the backbone (M_W,bb = 100 - 400 kg/mol), of the arms (M_W,a = 2.5 – 300 kg/mol) and the arm number at each end (q = 5-30) are systematically varied. The shear and elongational behaviour are investigated experimentally and modelled with the pom-pom and the Hierarchical Multi-mode Molecular Stress Function (HMMSF) model.

Shear thinning is found in small amplitude oscillatory shear (SAOS) measurements, depending on M_W,a, the backbone volume fraction and backbone self-entanglement. The zero-shear viscosity and the diluted modulus as a function of the backbone volume fraction are analysed. Additionally, criteria to predict backbone self-entanglement based on the effective backbone entanglement are investigated and compared with double reputation theory. The results of the pom-poms are compared with literature data of combs. In elongational flow, very high strain hardening factors > 100 are found. Following the pom-pom model and the Considère criterium, the SHF can be predicted based exclusively on the arm number q if the backbone is self-entangled by a factor of . For combs and pom-poms with similar molecular properties, similar SHF are obtained in elongational flow.

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Di, 23.04.2024 entfällt

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Johannes C. Brendel

University of Bayreuth

Tailored design of reactive polymers and nanostructures

Nature presents numerous examples for responsive structures, which react to subtle changes in their environment. In our group, various functional monomers and polymers are synthesized which react selectively to specific stimuli such as an oxidative environment or changes in pH. In the latter case, we realized amino-based polymers, which are selectively protonated in the biological most interesting range of pH 5-8. In another example, we utilize thioether groups to trigger a time-delayed release and degradation under oxidative conditions.

Another focus of our research is the controlled assembly of these functional polymers into nanostructures of specific shapes. Therefore, we investigate approaches such as poly­meri­zation in­duced self-assembly (PISA) or directed supramolecular interactions to guide the assembly of the functional polymer building blocks into different nanostructures. In the latter case, directing hydrogen bonds are employed to drive the assembly of funcionalized polymers into supramolecular bottlebrush-like fibres. The assembly follows a nucleation-growth mechanism which allows to tune the length of the fibers.

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Di, 16.04.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Sijbren Otto

Centre for Systems Chemistry, Stratingh Institute, University of Groningen (The Netherlands)

Oligomerization and Self-Assembly in the De-Novo Synthesis of Life

How the immense complexity of living organisms has arisen is one of the most intriguing questions in contemporary science. We have started to explore experimentally how organization and function can emerge from complex molecular networks in aqueous solution. 1 We focus on networks of molecules that can interconvert, to give mixtures that can change their composition in response to external or internal stimuli. Noncovalent interactions within molecules in such mixtures can lead to the formation of foldamers.2,3 In contrast, molecular recognition between molecules in such mixtures leads to their mutualstabilization, which drives the synthesis of more of the privileged structures (Figure 1). As the assembly process drives the synthesis of the very molecules that assemble, the resulting materials can be considered to be self-synthesizing. Intriguingly, in this process the assembling molecules are replicating themselves, where replication is driven by self-recognition of these molecules in the dynamic network.4 The selection rules that dictate which (if any) replicator will emerge from such networks are starting to become clear. 5 We have also witnessed spontaneous differentiation (a process akin to speciation as it occurs in biology) in a system made from a mixture of two building blocks.6 When such systems are operated under far-from-equilibrium flow conditions, adaptation of the replicators to a changing environment can occur. Replicators that are able to catalyse reactions other than their own formation have also been obtained, representing a first step towards metabolism.7,8 Rudimentary Darwinian evolution of purely synthetic molecules has also been achieved 9 and the prospect of synthesizing life de-novo is
becoming increasingly realistic. 10

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Di, 23.01.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Seema Agarwal

University of Bayreuth, Germany

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.

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Di, 16.01.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Jun.-Prof. Dr. Christian Franke

Friedrich Schiller University Jena, Germany

Nanometer Resolution and Single-Molecule Sensitivity -
Super-Resolution Microscopy for Polymer Research

Fluorescence based super-resolution microscopy methods, such as single-molecule localization microscopy (SMLM), have emerged as the prime tool to investigate structure-function relationships of cellular organelles with three-dimensional nanometer resolution and single-molecule sensitivity. The unique nature of SMLM, i.e. pinpointing molecular identities, has allowed a huge array of discoveries in the life sciences. Besides the often prominently featured ‘pretty pictures’ with unmatched spatial resolution of down to 10 nm, SMLM offers the unique feature of analyzing the localization data itself, which is commonly applied to cluster analyses, thus probing spatial inhomogeneities in the target structure with distinct molecular identities based on their spectral fingerprint, including anisotropy.

Although the main field of application of SMLM and related super-resolution techniques lies in cell biology and connected clinical research, its unique features regarding the multi-colour, nanometric sampling of the target structure, topology and homogeneities in large fields of view and volumes yield huge potential in polymer research. For instance, we currently apply SMLM to study the nanoscale structure-function relationship of polymeric nanoparticles, utilized for drug delivery. Here, the goal is to correlate the properties of the polymeric particle to their intracellular fate, to yield a feedback loop to finally design nanoparticles of highest efficacy and lowest toxicity.

Recently, we also started to apply SMLM to more fundamental polymeric systems, e.g. the nanoscale architecture of polymeric hydrogels in different states of hydration. SMLM usually requires aqueous environments, due to the demanding requirements regarding the photo-physical properties of commonly used dyes. We thus established a novel approach, at the same time enabling SMLM in solid state polymeric, i.e. dry, environments, and utilizing these structures as novel reference structures for super-resolution microscopy. This opens up entirely new avenues for SMLM analyses of visualizing polymer matrices with nanometer resolution and changes therein in context of potential ligands or changing environmental conditions.

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Di, 09.01.2024

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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PD Dr. Robert Göstl

DWI – Leibniz Institute for Interactive Materials, Aachen, Germany
and RWTH Aachen University, Germany

From force-reporting to force-resistant: using mechanochemistry to understand polymer materials

One of the grand scientific challenges of our time is how the remarkable properties of matter emerge from the complex correlations of their molecular constituents. We perform research adhering to this principle by following the results of mechanical stress and strain on macromolecular materials, which often requires to survey large samples with molecular level resolution due to the multiscale nature of force.

To do so, we firstly design and synthesize molecular optical force probes and the respective macromolecular materials made from them in a transdisciplinary approach.^[1] We mainly employ Diels-Alder adducts of π-extended anthracenes and maleimides reporting over covalent bond scission events due to their sensitive nature and facile tunability of their optical properties.^[2,3]

Secondly, we use these mechanofluorophores to investigate the mechanical behavior of complex and non-uniform high-performance polymers, such as rubbers and composites, and soft matter, e.g., hydrogels and colloidal hydrogel networks, in detail developing novel methodologies. From these experiments, we aim to draw conclusions over the behavior of these materials under force.^[4,5]

Eventually, we strive to use the insights gained from this to develop materials with improved mechanical properties by, e.g., introducing pathways to dissipate stresses at the locations where they are most critical or to self-reinforce or by the activation of latent functional motifs to perform mechanically activated chemical reactions.^[6]

References
[1] S. He, M. Stratigaki, S. P. Centeno, A. Dreuw, R. Göstl, Chem. Eur. J. 2021, 27, 15889–15897.
[2] D. Yildiz, C. Baumann, A. Mikosch, A. J. C. Kuehne, A. Herrmann, R. Göstl, Angew. Chem. Int. Ed. 2019, 58, 12919–12923.
[3] C. Baumann, M. Stratigaki, S. P. Centeno, R. Göstl, Angew. Chem. Int. Ed. 2021, 60, 13287–13293.
[4] E. Izak-Nau, S. Braun, A. Pich, R. Göstl, Adv. Sci. 2022, 9, 2104004.
[5] S. He, S. Schog, Y. Chen, Y. Ji, S. Panitz, W. Richtering, R. Göstl, Adv. Mater. 2023, 35, 2305845.
[6] D. Campagna, R. Göstl, Angew. Chem. Int. Ed. 2022, 61, e202207557.

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Do, 14.12.2023 - Sondertermin

14:15 Uhr im Seminarraum 1.02 Von-Seckendorff-Platz 1, 06120 Halle

Prof. Dr. Alexey V. Lyulin

Soft Matter and Biological Physics, Department of Applied Physics and Science Education, Technische Universiteit Eindhoven, 5600 MB, Eindhoven, The Netherlands and Center for Computational Energy Research, Technische Universiteit Eindhoven, 5600 MB, Eindhoven, The Netherlands

Multiscale modelling of the glass transition in Nafion membranes for
perspective flow and fuel batteries

Nafion is a commonly used polyelectrolyte membrane (PEM) in fuel cells and flow batteries. Nanocomposites of Nafion are used to enhance temperature resistance and proton conductivity. The properties of hydrated membranes, and the water influence on Nafion glassy behavior is very important. We first report molecular-dynamics simulations of Nafion films of different thicknesses between two potential walls of variable wettability [1]. The water cluster sizes showed an increase with film thickness for the high wettability cases, in agreement with SAXS experiments. The in-plane water diffusion was considerably enhanced for the high wettability walls. We report the modelling of the annealing effects on both structure, dynamics and electric conductivity of the membranes. We observe [2] strong antiplasticization effect and increase in the glass-transition temperature upon hydration. The hydrophilic channels evolution upon annealing and associated changes in ion diffusion and electric conductivity will be discussed. Large scale Dissipative Particle Dynamics simulations were carried out as well to study the temporal evolution of the water-PEM interface as a function of the PEM side-chain length.

Acknowledgements
This work was done as a part of the FOM-SHELL 15CSER13 research project and was carried out on the Dutch national e-infrastructure with the support of SURF Cooperative. AVL and AV both thank DUO-India Fellowship Program for the possibility to visit and work at IISER Pune and TU Eindhoven, correspondingly. Arun Venkatnathan thanks DST Nanomission Thematic Unit (SR/NM/TP-13/2016(G)).

References
[1] S. Sengupta, A. V. Lyulin, J. Phys. Chem. B, 122, 6107-6119, 2018.
[2] A. V. Lyulin S. Sengupta, A. Varghese, P. Komarov and A. Venkatnathan, ACS Appl. Polym. Mater., 2, 5058-5066, 2020.

Di, 12.12.2023

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Andreas Herrmann

Leibniz Institute for Interactive Materials DWI, Aachen, Germany
RWTH Aachen, Germany

Sonopharmacology and Sonogenetics: Activating drugs, proteins and genes by ultrasound

Remote controlling biological systems is an exciting endeavour because it is the offspring for new therapies and allows answering fundamental biological questions. In this context, the field of optogenetics has enabled the understanding of neural circuits and disorders.^[1,2] However, current optogenetic techniques are hampered by the low penetration of light into tissue and hence often require invasive surgical procedures to deliver photons to target cells. Therefore, ultrasound (US) was used as alternative trigger since US can deeply penetrate tissue with high spatiotemporal control and has been safely applied in the clinic for many decades.^[3] Our group has developed general molecular technologies to activate drugs, proteins and nucleic acids by US employing principles from polymer mechano-chemistry.^[4,5] Two types of mechano-sensitive carriers have been discovered, i.e. high molar mass polynucleic acid aptamers and colloidal hydrogel microbubbles. Polynucleic acids fabricated by enzymatic reactions undergo covalent and non-covalent bond cleavage induced by shear forces originating from US-induced cavitation bubbles. These nucleic acid carriers harbouring different bioactive payloads allow the activation of small bioactive molecules and drugs that can initiate gene expression, kill pathogens or cure diseases.^[4,5] Moreover, the activation of thrombin by US allows the general control over protein activity in combination with split inteins.^[6] A particular emphasis is paid to reducing US energies to make these sonogenetic and sonopharmacological systems compatible with living matter.^[7] In this realm, microbubbles containing a hydrogel shell with embedded mechanophores were developed.^[8]

References:
[1] Haubensak W, Kunwar PS, Cai H, Ciocchi S, Wall NR, Ponnusamy R, Jonathan Biag, Dong H-W, Deisseroth K, Callaway EM, Fanselow MS, Lüthi A, Anderson DJ, Nature (2010) 468: 270.
[2] Kravitz AV, Freeze BS, Parker PR, Kay K, Thwin MT, Deisseroth K, Kreitzer AC, Nature (2010) 466: 622.
[3] Wang T, Wang H, Pang G, He T, Yu P, Cheng G, Zhang Y, Chang J, ACS Appl. Mat. & Interf. (2020) 12: 56692.
[4] Paul A, Warszawik EM, Loznik M, Boersma AJ, Herrmann A, Angew. Chem. Int. Ed. (2020) 59, 20328.
[5] Huo S, Zhao P, Shi Z, Zou M, Yang X, Warszawik E, Loznik M, Göstl G, Herrmann A, Nat. Chem. (2021) 13: 131.
[6] Zhao P, Huo S, Fan J, Chen J, Kiessling F, Boersma AJ, Göstl R, Herrmann A, Angew. Chem. Int. Ed. (2021) 60, 14707.
[7] Yildiz D, Göstl R, Herrmann A, Chem. Sci. (2022) 13: 13708.
[8] Xuan M, Fan J, Ngoc Khiêm V, Zou M, Brenske KO, Mourran A, Vinokur R, Zheng L, Itskov M, Göstl R, Herrmann A, Adv. Mat. (2023) published online doi.org/10.1002/adma.202305130.

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Di, 05.12.2023

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Felix H. Schacher

Friedrich Schiller University Jena, Germany

Can polymers do magic? - The role(s) of polymeric templates in light-driven catalysis

Polymers are a versatile class of materials with almost unlimited  combinations of functional groups being present in close proximity. This  in combination with a widely tunable solubility has enabled quite a  range of examples where building blocks for light-driven catalysis (i.e.,  photosensitizers and catalysts) are immobilized using either covalent  anchoring or non-covalent interactions. During recent years, we have  developed different soft matter matrices for either light-driven  hydrogen evolution (HER) or water oxidation (WOC) based on unimolecular  graft copolymers, block copolymer micelles, hydrogels, or nanoporous  block copolymer membranes. In all cases, close proximity of the  immobilized building blocks facilitated light-driven reactivity, but we  also observed additional effects during our studies, such as prolonged  lifetime of photosensitizers, altered degradation pathways, or the  possibility to repair / exchange catalysts or sensitizers. In addition,  some effects imply that – especially in case of polyampholytic graft  copolymers – the polymeric matrix is also involved in charge transport,  presumably due to the high charge density present along the polymer  backbone. Altogether, in this contribution we try to derive some general  guidelines for the design of (charged) soft matter matrices for  light-driven catalysis.

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Di, 28.11.2023

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Dr. Mehdi D. Davari

Leibniz Institute of Plant Biochemistry, Germany

Synergizing Science and Innovation: Developing Sustainable Detergents with Computational Modeling and Experiments

The modern laundry detergents present a complex interplay of diverse components - enzymes, surfactants, builders, bleaching agents, and minor additives, all synergistically engineered to remove stains. A fundamental comprehension of the molecular interactions between these components stands as a pivotal avenue for advancing the formulation, performance, and sustainability of detergent industry products.

In this presentation, I will delve into the research conducted within the Henkel Innovation Campus for Advanced and Sustainable Technologies (HICAST) between 2014 and 2019 at RWTH Aachen University. HICAST's primary focus was on developing novel, sustainable laundry detergents by unlocking the mysteries surrounding interactions among detergent components. Our primary objective was to deeply probe the molecular dynamics governing the boosting of protease activity in detergent enzymes when interacting with polymers and surfactants. Our multidisciplinary approach, integrating computational modeling (atomistic and coarse-grained molecular dynamic simulations), alongside colorimetric analysis and biophysical characterization methods (CD, FCS, ITC, and DLS), and innovative enzyme engineering, outlined a promising workflow. This methodology provided us with profound molecular insights into the mechanisms that govern this enhancement and effectively elevate detergent performance. Importantly, the profound understanding of the fundamental principles underpinning increased protease performance holds promise for applications across diverse detergent enzymes. It is poised to revolutionize the engineering of enzymes, polymers, and surfactants compositions in the realm of modern laundry detergents.

This presentation offers a glimpse into a realm where computational modeling, enzyme engineering, and soft matter engineering converge, opening the door to an era of more sustainable, high-performing detergent formulations.

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Di, 21.11.2023

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Prof. Dr. Karsten Mäder

Martin Luther University Halle-Wittenberg, Institute of Pharmacy, Germany

Biodegradable polyesters for drug delivery: materials and performance

Biodegradable polyesters are important materials for controlled drug delivery. Until now, mainly polylactide (PLA) and poly-(lactide-co-glycolide) (PLGA are used to deliver the drug molecules over several weeks to months. The talk will discuss how material properties and processes, but also the size (nano- vs. micron range) are linked with the control of drug delivery. Despite PLA and PLGA dominate the field until now, they have several drawbacks. The formation of the acidic monomers lactic and glycolic acid leads to the formation of highly acidic microenvironments in vitro and in vivo ^1–3 and might cause acylation and degradation of drug molecules prior release ⁴. It also triggers autocatalytic polymer degradation which leads to the paradox of a faster degradation of larger particles and implants. Acidic microenvironments can be prevented by the use of PEG-PLGA block polymers. Block polymers permit also and better release of hydrophilic drugs, because a zero-order release with no lag time can be achieved ⁵. The presentation will discuss the monitoring of the polymer microenvironment by EPR spectroscopy and optical imaging. It will also highlight the need for the development of alternative polymers for drug delivery purposes.

References:
1. Mäder, K., Gallez, B., Liu, K. J. & Swartz, H. M. Non-invasive in vivo characterization of release processes in biodegradable polymers by low-frequency electron paramagnetic resonance spectroscopy. Biomaterials17, 457–461 (1996).
2. Liu, Y. & Schwendeman, S. P. Mapping microclimate pH distribution inside protein-encapsulated PLGA microspheres using confocal laser scanning microscopy. Mol. Pharm.9, 1342–1350 (2012).
3. Schädlich, A., Kempe, S. & Mäder, K. Non-invasive in vivo characterization of microclimate pH inside in situ forming PLGA implants using multispectral fluorescence imaging. J. Control. Release179, 52–62 (2014).
4. Lucke, A., Kiermaier, J. & Göpferich, A. Peptide Acylation by Poly(α-Hydroxy Esters). Pharm. Res. 2002 19219, 175–181 (2002).
5. Elena de Souza, L. et al. Has PEG-PLGA advantages for the delivery of hydrophobic drugs? Risperidone as an example. J. Drug Deliv. Sci. Technol.61, 102239 (2020).

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Di, 14.11.2023

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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Dr. Martina Delbianco

Max Planck Institute of Colloids and Interfaces, Postdam-Golm, Germany

Synthetic carbohydrate-based materials

Natural biopolymers have inspired the development of synthetic analogues capable of adopting defined conformations and forming programmable three-dimensional architectures. These compounds are mainly based on peptides and nucleic acids, that are well understood at the molecular level. In contrast, the complexity of carbohydrate synthesis and structural analysis have prevented access to synthetic carbohydrates capable of adopting defined geometries. In the Delbianco group, we prepare well-defined oligosaccharides to understand how the primary sequence affects the carbohydrate conformation.¹ With multiple analytical techniques, we study the conformation of single carbohydrate chains² and explore how several carbohydrate molecules aggregate to form a material³. Building on this fundamental knowledge, we present the rational design and synthesis of a glycan adopting a stable secondary structure,⁴ challenging the common belief that glycans are not capable of folding due to their flexibility. The ability to control the conformation of glycans could lead to the generation of programmable 3-D architectures, with applications in catalysis and nanotechnology.

References:
1. Y. Yu, T. Tyrikos-Ergas, Y. Zhu, G. Fittolani, V. Bordoni, A. Singhal, R. J. Fair, A. Grafmüller, P. H. Seeberger, M. Delbianco, Angew. Chem., Int. Ed. 2019, 58, 1433-7851
2. X. Wu, M. Delbianco, K. Anggara, T. Michnowicz, A. Pardo-Vargas, P. Bharate, S. Sen, M. Pristl, S. Rauschenbach, U. Schlickum, S. Abb, P. H. Seeberger, K. Kern, Nature 2020, 582, 375-378.
3. G. Fittolani, D. Vargová, P. H. Seeberger, Y. Ogawa, M. Delbianco, J. Am. Chem. Soc. 2022, 144, 12469-12475.
4. G. Fittolani, T. Tyrikos-Ergas, Y. Yu, N. Yadav, P.H. Seeberger, J. Jiménez-Barbero, M. Delbianco, Synthesis of a glycan hairpin, Nat. Chem., 2023, 15, 1461

Di, 07.11.2023

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

We try to offer the hybrid option, but cannot guarantee it!

Dr. Eva von Domaros

Friedrich Schiller University Jena, Germany

Can polymer properties be predicted from theory?

The material class of polymers is not only extremely large and complex. Polymers are important parts of our daily lives as plastics or biopolymers like sugars or the DNA backbone. The theoretical understanding---let alone the prediction---of polymer properties is very demanding. The reason therefore is a combination of polymer characteristics. Very large system sizes that easily reach thousands of repeating subunits are hardly feasible for accurate electronic structure methods such as DFT. Furthermore, in contrast to crystalline compounds, polymers are amorphous and lack periodic symmetry, which can be exploited for crystals in periodic calculations. Theoretical models which are capable of treating these systems necessarily apply approximations such as parameterized force fields and, hence, are less accurate and reliable.

In this presentation, a novel approach to understand and later on predict macroscopic properties of this diverse material class is presented. The so-called Quantum Cluster Equilibrium (QCE) method is based on a statistical approach which allows to transfer highly reliable electronic structure data to macroscopic phases. The QCE method will be introduced and demonstrated at the example of liquid systems. Afterwards, the extension to amorphous systems such as polymers will be demonstrated, and promising applications will be presented. Finally, it will be shown which properties are within the reach of this method and the limitations will be discussed.

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Di, 24.10.2023

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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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.

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Di, 17.10.2023

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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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.

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Di, 10.10.2023

16:15 Uhr im Seminarraum 1.27 Von-Danckelmann-Platz 4, 06120 Halle

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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.

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