In 2022, the EDC focuses on “Interface Interactions: Experiment & Modeling”. We want to address experimental and theoretical investigations of interfaces, for example in foams and emulsions, and in this context discuss aspects like interface stability, transport processes and interactions at interfaces.

Spoken Language: English Category: Fundamental Research To mix an aqueous (polar) and a nonpolar (oily) phase to a homogeneous, transparent phase, usually surfactants are used. Then, typically micelles occur or even liquid crystalline structures if a high amount of surfactant is present. Alternatively, water and oil can be mixed by so-called hydrotropes. SXS or SCS are prominent examples, but sometimes even ethanol can be sufficient. Usually, much more hydrotrope is necessary to get a homogeneous, transparent phase than with surfactants. On the other hand, surfactants may be unwanted, because they may perturb the product or lead to environmental or toxicity problems. For a long time, it was common sense that hydrotropes cannot form micelles or any other nanostructures with interfaces between oily aggregates and the aqueous surroundings in the stable transparent mixed phase. However, this is not always true. We could prove that sometimes even hydrotropes as simple as ethanol can form interfaces in oil-water mixtures. Such interfaces can be crucial for various chemical and biochemical reactions. For example, emulsion/microemulsion polymerisation can be done in such mixtures even in the absence of surfactants and the growth and final size of the polymers can be finely controlled just as in the presence of surfactants. The advantage is that the final product does not contain any traces of surfactants that could negatively influence the properties of the polymer. Another application is in the field of chemical (and biochemical) synthesis. With such nanostructured, surfactant-free systems, a wide field is open for chemical synthesis in essentially aqueous systems. This may open the way to more sustainable synthesis and even avoiding surfactants, which are still supposed to be mandatory in this field.

Spoken Language: English Category: Fundamental Research The ability to guide fast interfacial processes in multi-component non-equilibrium systems is a significant fundamental and practical task. Presented research demonstrates the potential of unique functional properties of volatile amphiphilic compounds (aroma molecules), such as high dynamic surface activity in a millisecond range, as well as the ability to desorb from the surface into the gas phase at times of the order of seconds, in the optimization of the dynamic processes of surface formation. Insights into the interfacial behavior of volatile surfactants (e.g. unsaturated terpene alcohols linalool, geraniol, nerol and aromatic alcohol benzyl acetate (BA)), as well as of their mixtures with conventional surfactants are provided by dynamic and static tensiometry studies. Application examples include miniemulsion polymerization, wetting and spreading phenomena, ink-jet printing, stabilization of emulsions, as well as the assessment of fragrance release from cosmetic and wellness formulations. In particular, a successful copolymerization of soybean oil-based monomer with styrene in miniemulsions, stabilized by mixtures of conventional surfactant sodium dodecylsulfate (SDS) and BA as a co-surfactant is reported. Upon substitution with BA up to 70% of the initial SDS amount, the main parameters of the polymerization (conversion, yield, coagulat) remain unaffected, while the average dimensions of latexes increase with increasing BA fraction from about 100 to 300 nm. The rheological characteristics and fragrance release of thixotropic oil-in-water emulsions correlate with the preparation procedure, confirming incorporation of aroma molecules into the interfacial layer. Finally, high resolution wetting experiments have demonstrated, that depending on the time scale and on the concentration of the added volatile surfactant, the latter can either accelerate or retard the spreading behavior of aqueous formulations. Reported here findings are envisaged to launch multiple applications of volatile amphiphiles in material science and fabrication.

Spoken Language: English Category: Fundamental Research Associative thickeners are typically composed of a hydrophilic polymer (“A”) framed by two hydrophobic end groups ("stickers", “B”). To confer new properties to such systems, we explore amphiphilic block copolymer poly(acrylamide)s BAB*, which contain one permanent hydrophobic sticker B, and one thermo-responsive "switchable" sticker B*. Above a specific temperature, this design results either in the formation of flower-like micelles via intra-micellar back-folding, or of micellar networks via inter-micellar bridging. In order to elucidate the mechanism of action, we functionalize the polymers with a naphthalimide dye on the permanent hydrophobic sticker end, and a coumarin dye at the opposite chain end. This fluorophore pair undergoes efficient Förster resonance energy transfer (FRET), enabling the investigation of back-folding vs. bridging during the thermally induced coil-to-globule phase transition of the polymers. Using a tailor-made surfactant-like chain transfer agent (CTA), the triblock-like polymers are synthesized from N,N‑dimethylacrylamide (DMA) as permanently hydrophilic and, e. g., N-isopropylacrylamide (NIPAM) as thermoresponsive blocks via RAFT polymerization. Their aggregation in aqueous solution as well as in o/w microemulsions is studied by fluorescence, turbidimetry and scattering methods, demonstrating how the chemical structure of the blocks influences phase behavior, self-assembly, and rheology.

Spoken Language: English Category: Fundamental Research Investigation of carbon dioxide (CO2) as sustainable resource is of fundamental interest for research and industrial applications. It can be used as a building block in chemical compounds such as polymers or surfactants. Substituting ethylene oxide (EO) units in abundantly produced non-ionic EO-surfactants by CO2 can increase the sustainability and save natural and fossil resources. Similarly interesting, introducing CO2 gives a new tuning parameter for non-ionic surfactants, allowing to better match particular application requirements and thereby a more economical consumption and potentially even opening up pathways for novel formulations. The possibility to use the CO2 content to tune the properties in different formulations e.g. microemulsions, nanoemulsions, macroemulsions and surfactant gels has been investigated using industrial relevant oils (decane, isopropylpalmitate, bis(2-ethylhexyl)carbonate) with different polarity. The influence of the CO2 groups on the physicochemical properties of those systems have been investigated by light scattering (LS), interfacial tension measurements (IFT), conductivity measurements and fluorescence imaging. It can be seen, that the use of CO2 containing surfactants lead to different results as systems with pure EO surfactants. Funding: This project is part of “DreamResourceConti” (033R222C) and funded by the German Federal Ministry of Education and Research (BMBF) within the funding priority “r+Impuls – Innovative Technologien für Ressourceneffizienz – Impulse für industrielle Ressourceneffizienz”.

Spoken Language: English Category: Fundamental Research Nanopores are a key component in various technologies from oil production, separation and sensing, to enzyme stabilization and release or delivery. Nanopore performance is to a large extend based on the small distance between the pore walls representing solid-fluid interfaces. Despite increasing understanding of nanopore performance and thus the role of interface proximity and spatial confinement, the performance gap between technological and biological pores with respect to transport remains a challenge. This talk will especially highlight the role of nanopore wettability and nanopore charge regulation with respect to its influence on nanopore accessibility and transport. Nanopore wettability and charge is regulated using molecular or polymer-based functionalization. In this context, the influence of polymer type, the influence of spatial confinement on apparent pKa, as well as strategies to adjust and switch nanopore wettability and wetting transitions of functionalized mesoporous silica films are discussed. Thereby, the spatial confinement as well as evaporation and condensation become detrimental at nanoscale pore sizes and thin films.

Spoken Language: English Category: Fundamental Research / Home Care, Detergents, Enzymes Enzymes and surfactants are both essential ingredients in the laundry detergent and both components determine the washing performance. Stabilization of enzymes in liquid laundry detergents is a challenge. In liquid systems, enzymes are in close proximity to other detergent ingredients and can easily be denaturated by high surfactant content or  chelators or solvents. Charged surfactants like linear alkylbenzene sulfonate show strong enzymes inactivation via disturbing the native folded state of the enzyme, while the nonionic surfactants do only show significant inactivation over time. Additionally, proteases could be destroyed by auto-digestion resulting in poor wash performance on proteinaceous stains. Advances in stabilization technology have improved the shelf life of enzymes in liquid detergents over last 2 decades. To better understand the surfactant and enzyme interactions in liquid laundry detergent formulations, we studied the effects of different surfactant types and surfactant combinations on enzyme structural stability, and washing performance in liquid model detergents using molecular modelling. We performed multiple molecular dynamic simulations to study the effects of different anionic and nonionic surfactant mixtures on the enzyme activity. Based on molecular dynamics data experiments were planned to test the enzyme storage stability, activity and washing performance by performing enzyme assay, high throughput washing tests and full-scale washing. With the present work we would like to show a path forward on how molecular modelling could assist in optimizing the surfactant compositions for enhanced enzyme stability resulting in improved detergency after storage.

Spoken Language: English Category: Fundamental Research Foams appear in many applications such as in personal care products, firefighting and food technology. An elegant tool to tune the foam stability is the addition of polymers of different charge, amphiphilicity or molecular architecture. Examples, which will be presented here are complexes of oppositely charged surfactants and polyelectrolytes, stimuli-responsive microgel particles and proteins. For understanding macroscopic foam properties, it is important to get deeper insight into the different length scales, i.e. the structuring of polymers at the air/water interface, in foam films, which separate the air bubbles from each other and in (macroscopic) foams. A challenge for studies of microgel-stabilized foam films are their massive inhomogeneities, which makes it difficult to measure the respective foam film thickness. To get insight into foam film properties, we use a camera based thin film pressure balance to study microgel-stabilized foam films in terms of disjoining pressure inside the foam films, drainage kinetics, and foam film stability. Therefore, we use two different methods: an intensity measurement for grey thin films (thickness < 100 nm) and a color assignment method for colorful thick films. Film thickness profiles give insights into particle bridging, agglomeration and network formation in the foam films. For a complete picture, small angle neutron scattering (SANS) measurements on macroscopic foams provide additional insights into the link between foams and single foam films. Because of this complex structure, modelling of SANS curves obtained from foams is challenging. Here, a newly developed model for the full description of these SANS curves is presented, yielding information about the internal structure of the foam. L. Braun, M. Kühnhammer, R. von Klitzing (2020): “Stability of aqueous foam films and foams containing polymers: Discrepancies between different length scales" Current Opinion in Colloid & Interface Science 50 101379.

1. Award Session "Moderated by Prof. Dr. Birgit Glüsen, TH Köln, University of Applied Sciences" Prize of the Division 2020 to Dr. Astrid Rohrdanz; Laudation: Marcus Gast, Umweltbundesamt Dessau-Roßlau GDCh Young Scientists Award 2022 (Bachelor, Master & PhD) Best PhD: Dr. Christoph Brudl, claro products GmbH & Technische Universität Graz Title: "Going green and clean – Is it possible? (Development of a Biodegradable High Performance Dishwashing Detergent)" Abstract: Nowadays, most people get a more environmental-friendly oriented mindset and are better informed than ever before. In 2017, the EU made the first move towards more sustainability by prohibiting phosphate in dishwashing detergents. Dishwashing detergent manufacturers reacted by using more non-biodegradable polyacrylates and phosphonates, which are not toxic, but lead to additional unnecessary pollution of the environment. Therefore, the scope of the thesis was to evaluate biodegradable polycarboxylates in order to formulate a biodegradable dishwashing detergent with a comparable performance. The main part of this work was the development of a builder- and surfactant-system that results in as little spotting and filming as possible. After many different formulations it was possible to create, with the help of different analytical methods like SEM, Raman, IR, AFM and XPS, a formulation equally good in its performance compared to common benchmark products. With the development of a new biodegradable silver protecting agent during the course of this work, it is now also possible to have good silver protection without using benzotriazole, which is toxic to the environment. At the end, the biodegradation of the best formulation was confirmed by an OECD 301B test. Best Master Thesis: Hailey Poole, Universität Stuttgart & Queen’s University Title: "CO2-Switchable Foaming Agents" Abstract: In industry, foams are often required for part of a process but can be detrimental in downstream processes. Traditionally to control undesired foam, antifoaming and/or defoaming agents are used. Unfortunately, these additives change the composition of the foaming solution preventing the recovery and reuse of the foaming agent. A solution to having foam control without additional chemicals is using a molecule that can be switched between being a surfactant and being a defoaming agent. Such molecules are called switchable surfactants, they can be switched between a form that has significant surface activity (the ‘‘on’’ form) and a form that has less surface activity or less capability of stabilizing a foam (the ‘‘off’’ form). CO2 is an advantageous pH trigger for this process as it is non-toxic, inexpensive, and does not lead to salt buildup as can occur with acids and bases. While the bulk of attention has been on CO2-switchable surfactants with switchable head groups, we have designed CO2-switchable surfactants where the surfactant head group is permanently anionic, cationic, or nonionic and the CO2-responsive group is placed in the middle of the hydrocarbon tail. Under air, the CO2-responsive group is neutral and acts as part of the hydrophobic tail. When this form of the molecule is added to water and energy is applied, a stable foam is produced. In the presence of CO2, the CO2-responsive group in the tail becomes protonated and reduces or disrupts the amphiphilic nature of the molecule, which in turn, disables the molecule's ability to stabilize a foam. These surfactants are advantageous in industrial applications where foam is needed under air. When the foam is no longer desirable, CO2 can be added to the system, thus providing easier post-processing and recycling of the surfactant solution. Best Bachelor Thesis: Sophia Botsch, University of Stuttgart Title: "Spheres Become Polyhedrons: Surfactants Make it Happen" Abstract: The polymerization of monodisperse water-in-monomer emulsions results in monodisperse macroporous polymers with non-spherical pores that have layered pore walls. We identified that this morphology is caused by surfactant diffusion and phase separation during polymerization. Solid polymer foams combine the advantageous properties of foams and polymers. The resulting materials are both light-weight and insulating. However, the properties to some degree depend on the structure which is not easily customized using common production methods of polymer foams. Using monodisperse water-in-monomer emulsions as polymerization templates solves this issue, though also raising another question: why does the shape of the pores changes from a spherical template to a polyhedral polymer foam when a water-soluble initiator is used? We studied the morphology of macroporous polymers with varying surfactant mass fractions that were polymerized from emulsion templates. The structure as well as size of the pores and the thickness of the layers was determined via scanning electron microscopy. In addition, a ternary phase diagram that simulated the polymerization was conducted to study the response of monomer/surfactant mixtures to polymerization. We found that the higher the surfactant concentration, the thicker the porous inner layer of the wall, thus indicating a diffusion process of excess surfactant molecules into the inner monomer phase caused by phase separation between monomer and polymer during polymerization. This process also causes some of the surfactant molecules to diffuse onto the water-monomer interface, thus enabling the latter to increase its area and changing the pore shape from spherical to polyhedral. 2. Short Introduction of Scientific Poster by Authors (EDC) Poster Session: Moderated by Dr. Felix Müller Date: Wednesday, 26 October 2022 Time: 12:30 - 13:00 Location: Auditorium Find further information about the poster presentations on the page: Poster Presentations

Lunch-Time Poster Tour with Authors (EDC) Date: Wednesday, 26 October 2022 Time: 13:00 - 14:30 Location: Second Floor Foyer Language: English Find further information on the page: Poster Presentations

Spoken Language: English Category: Fundamental Research Adsorption of amphiphilic molecules to aqueous interfaces occurs in many technological and biological settings, sometimes desired (stabilization of foams), while other times not (contamination). I will discuss how atomistic computer simulations can help us elucidate molecular mechanisms of surfactant adsorption, ranging from short-chain alcohols to double-tail lipids. Small surfactants form loose monolayers and exhibit rapid exchange between the interface and bulk, which can be followed in the simulations. Surfactants with longer alkyl chains adsorb as denser monolayers and exchange on experimental timescales that are too slow to be captured in simulations, which challenges molecular modeling. The modeling of this regime requires advanced computational techniques that connect interface and bulk phases via precise determinations of their chemical potentials. Finally, double-chain surfactants (also called "lipids") do not exchange between bulk and interface both on experimental and simulation timescales. They exist as bilayer aggregates already in solution and adsorb to surfaces in the form of monolayers only under certain conditions. As it turns out, a universal determiner for adsorption is the wetting contact angle of the surface. Only surfaces with contact angles larger than around 60-70° are capable of forming lipid monolayers.

Spoken Language: English Category: Fundamental Research / Bio-Surfactants Plasmamembranes of procaryotes are represented by a large share of lipids such as phosphatidylglycerols. In this study the role of charged lipids in the plasma membrane is investigated with respect to the interaction of the antiviral saponin aescin with the membrane. Aescin is a natural surfactant which can be found in the horse chestnut and is known for its anti- inflammatory, anti-exudative, anti-oedematous and venotonic properties.[1-3] Small unilamellar vesicles (SUVs) made of 1,2-dioleoyl-sn-glycero-3-phosphoglycerol (DOPG) with different amounts of aescin are analysed by small angle neutron and X-ray scattering (SANS/SAXS). Furthermore, the chain-chain correlation distance of lipid/saponin mixtures in the SUV struc- tures is studies by wide angle X-ray scattering (WAXS). Small angle scattering data are evaluated with the Kratky-Porod (KP) and modified Kratky-Porod (MKP) method as well as a Guinier approximation. Afterwards the small angle scattering data is Fourier transformed with the software package GIFT.[4] Wide angle scattering data is analyzed by using Lorentzian fits to de- termine the chain-chain correlation distance.  Complete miscibility of DOPG and aescin is found even at a lipid/saponin ratio of 1:1. This is surprising since aescin is known to have haemolytic effects and degrades vesicels made of other lipids. [1] S. G. Sparg, M. E. Light, J. van Staden., Journal of ethnopharmacology 94 (2-3) (2004), 219–243. [2] C. R. Sirtori, Pharmacological research 44 (2001), 183-193. [3] R. Geisler, C. Dargel, T.Hellweg, Molecules 25(1) (2020), 117. [4] Bergmann, A.; Fritz, G.; Glatter, O., Journal of Applied Crystallography 33 (2000), 1212-1216.

Spoken Language: English Room: Auditorium

Spoken Language: English Category: Fundamental Research The historical surfaces of artistic and cultural objects can be regarded as the ‘faces’ of these pieces of art. The surfaces are often soiled as a result of long-term exposure to environmental influences. Their cleaning represents important challenges as each surface requires a tailor-made cleaning method to remove dirt without damaging the art piece. Recent research shows that foamed detergents can clean far more efficiently than non-foamed ones. Not only do they reduce the amount of detergents by up to 90%, but they also generate additional physical cleaning mechanisms which await to be understood and exploited. In particular, the processes acting at the contact zone between the aqueous foam and the non-aqueous “dirt” must be clarified. In a collaboration with the “Bavarian Administration of State-Owned Palaces, Gardens and Lakes”, the University of Cologne, the Institut Charles Sadron in Strasbourg and the University of Stuttgart, we work on understanding the different mechanisms involved in foam-based cleaning, and to exploit this understanding to develop innovative cleaning methods. Our current understanding of and progress on the subject will be presented, including the surprising observation that unstable foams clean better than stable foams: Less is More!!!

Spoken Language: English Category: Fundamental Research Repeated washing and normal wear and tear can minimize the strength and appearance of textiles. Consequently, various ingredients and processes have been developed to prolong the textile lifecycle. Textiles are derived from both synthetic and natural sources encompassing diverse chemistries. Thus, finding compatible and sustainable ingredients to perform the desired maintenance properties can be a difficult, resource-consuming task. Given the market demand for sustainable products in the personal care industry, the use of digital technologies as a resource-efficient tool has grown tremendously. At Ashland, we pride ourselves on the implementation and use of modeling to enhance our innovation pipeline. The Digital Innovations team has implemented advanced simulation methods within our in silico laboratory to provide insight and direction to problems faced in our targeted industries. Here, we present various scales of molecular modeling to uncover the unique molecular interactions of active ingredients with representative textiles. We highlight next-generation sustainable technologies that improve important maintenance properties of textiles including color protection, anti-greying, and strengthening. For color protection and strengthening, all-atom molecular dynamics simulations elucidate the interfacial interactions of ingredients with the textile surface. For anti-greying, coarse-grained molecular dynamics simulations uncover the complex mechanism of anti-soil redeposition of various soils onto the surface of textiles. In all cases, application experiments validate the proposed molecular models.  

Spoken Language: English Category: Fundamental Research The utility of detergents for applications is determined by their overall polarity and shape. The ability to systematically scale both detergent properties across a large chemical space has not yet been achieved. Regardless of the application, optimal detergents are therefore routinely identified by empirical tests, which can drive up the time and costs of projects. Here, this fundamental challenge is addressed by introducing a scalable detergent design. First, combinatorial synthesis is presented to enable the rapid preparation of hybrid detergents that differ gradually in terms of their polarity and shape. Second, established theoretical models are applied to monitor gradual changes in overall polarity and shape of hybrid detergents, such as the hydrophilic-lipophilic balance (HLB) and the packing parameter. To finally exemplify utility, scalable hybrid detergents are used to solve a medically relevant question: Does the structure or the concentration of detergents define the ability to maintain membrane protein function throughout purification? The results obtained in the context with membrane protein research demonstrate how scaling the polarity and shape enabled by hybrid detergents can advance structure-property studies for the benefit of individual applications. This work is permitting access to an unexplored part of the detergentome (totality of all detergents) and setting the groundwork for a new way of thinking in the field of detergent design. Structural scalability will facilitate the optimization of detergents for challenging future applications.

Scientific Poster Session with Authors incl. Award Ceremony (EDC) Date: Wednesday, 26 October 2022 Time: 17:10 - 17:30 Location: Second Floor Foyer Language: English Find further information on the page: Poster Presentations