In 2023, the EDC focuses on “Polymers in Water – Quo vadis?” We want to look at the future role of water-soluble polymers, addressing topics such as self-assembly, advanced manufacturing processes, water treatment, use in existing and new applications, and general degradability of such materials.

Spoken Language: English Category: Fundamental Research We will report on the development of new monomers and polymers derived from renewable resources. We have utilized a number of different sources to create a wide range of monomers and polymers. These sources include sorbitol, lactide, ε-caprolactone and fatty acids that are derived directly from nature, including from tree bark and oils from waste seeds. Our group has developed significant expertise in utilizing supercritical carbon dioxide (scCO2). In particular, we have exploited the low viscosity and high diffusivity of scCO2 to create a highly efficient and reversible plasticizer. This in-situ plasticization allows us to perform polymerisation reactions at temperatures as low as 40°C; much lower than is possible under conventional operating conditions. In some cases, these lower temperature operating conditions have opened up the opportunity to use enzymatic catalysts to yield new polymeric materials from renewable monomers. We will also report on the preparation of a range of new monomers derived from terpenes that we have utilised to create new di and terblock copolymers. These have shown wide application as surfactants, coatings, consolidants for archaeological materials and as hard-soft-hard block materials that can act as pressure sensitive adhesives. We will also demonstrate new applications and opportunities in 3-D printing.

Spoken Language: English Category: Fundamental Research The combination of polymers as thickener with microemulsions as carrier for hydrophobic substances results in an interesting colloidal system. A main interest is to control the structure and properties of those polymer-microemulsion systems by changing the different parameters, such as pH, salt, or temperature. Formerly, hydrophobically modified (HM) multiarmed polymers were investigated in mixtures with oil-in-water (O/W) microemulsions in respect to network formation and the resulting rheologic properties. Of special interest are hydrophobically modified thermoresponsive (HMTR) block copolymers in aqueous solution which can be used as thermo-active thickeners or thermo-responsive amphiphiles for solubilization of hydrophobic molecules. However, the solubilization capacity of such systems is generally low. Hence, the combination with microemulsions (MEs) as carriers for hydrophobic substances results in loaded systems, where the rheologic properties of the microemulsion solution can be tuned and switched via temperature. A biofriendly microemulsion consisting of Tween20 (polyoxyethylene-(20)-sorbitan monolaurate) as surfactant, 2-ethylhexyl-glycerol as cosurfactant, isopropylpalmitate as oil and water as solvent was used. Accordingly, various ME–polymer mixtures were studied for which three different block copolymer architectures of BAB*, B2AB*, and B(AB*)2 type were employed. Here, “B” represents a permanently hydrophobic, “A” a permanently hydrophilic, and “B*” a TR block. For the TR-block, three different polyacrylamides were used, which all exhibit a lower critical solution temperature (LCST). For a well selected ME concentration, these block copolymers lead to a viscosity enhancement with rising temperature. This phenomenon is caused by the formation of a transitory network mediated by TR blocks, as evidenced by the direct correlation between the attraction strength and the viscosity enhancement. For applications requiring a high hydrophobic payload, which is attained via microemulsion droplets, this kind of tailored temperature-dependent viscosity control of surfactant systems should therefore be advantageous.

Spoken Language: English Category: Fundamental Research Biosurfactants are seen as a greener alternative to conventional surfactants. However, the physical-chemical properties of biosurfactants differ significantly from those of usual surfactants. Since a typical formulation would not consist of just one single biosurfactant, a deep understanding of the interaction of biosurfactants with other surfactants present in the formulation is required. Hence, we provide a comprehensive study of this interaction including biosurfactants and co-surfactants using NMR, dynamic light scattering, fluorescence correlation spectroscopy, (dynamic) surface and interfacial tension and phase behavior techniques. In the talk, we discuss the different interfacial activities, aggregation structures and adsorption kinetics of various surfactant combinations. Their properties under equilibrium and non-equilibrium will be examined. Consequently, we present promising efficient surfactant systems for future applications.

Spoken Language: English Category: Fundamental Research The horse chestnut (Aesculus hippocastanum) seed extract belongs to the group of plant derived bio-surfactnats (saponins) and has proven useful in clinical therapy. Moreover, it is also studied due to its potential anti-carcinogenic properties. The main active ingredient, β-aescin, is used as an anti-inflammatory agent in the treatment of chronic venous insufficiency and to prevent oedema. [1, 2] In the context of pharmacological activity, the interaction of the biosurfactant β-aescin with biological membranes is of great interest. [2, 3] In our present work, the temperature-dependent interaction of high amounts of β-aescin with the lipid DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) is investigated by small-angle X-ray scattering (SAXS) and UV-vis turbidity measurements. At temperatures above the phase transition temperature (Tm ≈41.3 °C) aescin-stabilised DPPC bicelles assemble into extended bilayers and at higher temperatures into larger multilamellar structures. The self-assembly and final morphology are highly dependent on the phospholipid-to-aescin ratio and the actual temperature. It is also found that all structural changes are completely reversible by cooling to the initial temperature. 1. J. M. R. Patlolla, C. V. Rao, Current Pharmacology Reports, 2015, 1, 170–178. 2. D. Domanski, O. Zegrocka-Stendel, A. Perzanowska, M. Dutkiewicz, M. Kowalewska, I. Grabowska, D. Maciejko, A. Fogtman, M. Dadlez and K. Koziak, PloS one, 2016, 11, e0164365. 3. R. Geisler, M. C. Pedersen, N. Preisig, Y. Hannappel, S. Prévost, R. Dattani, L. Arleth and T. Hellweg, Soft Matter, 2021, 17, 1888–1900.

Spoken Language: English Category: Fundamental Research Introduction Thanks to their unique properties, water-soluble polymers (WSPs) find application in many products, such as in home and personal care or agricultural formulations[i]. In this presentation, we show, how the gained know how of biodegradation for structural biodegradable polymers can be adapted and transferred to WSP`s. Structural polymers as role model for the investigation of polymer biodegradation Different technologies have been developed over the past years together with our cooperation partners to elucidate the fate of polymeric materials in soil. 13C-labelling combined with different analytical techniques allowed to quantitatively track the polymeric material during the biodegradation process and to close the mass balance[ii]. Evidence was provided that carbon from synthetic biodegradable polymers is incorporated in the active biomass of microorganisms during the biodegradation process[iii]. Microorganisms and enzymes from different soils have been identified showing that a broad variety of fungi and bacteria. Biodegradation of WSP`s: key considerations, status and path forward A deep understanding of the environmental fate of WSP`s can only be achieved with a holistic approach to the topic, from the chemical structure to the test methods, from the environmental factors to the biology (microbes, enzymes). Testing of the biodegradation of WSP`s in laboratory can build on the existing test methods developed for small molecules (e.g. OECD 301 B and F) and plastics (e.g. ISO 14851) whereas adaptation might be needed, due to the different nature of the material under investigation. In addition, 13C-labelling and microbial enrichments can provide valuable insight into the biodegradation processes. Preliminary results will be presented and a proposal for biodegradation testing scheme for WSP’s. [i] Zumstein et al., (2022), https://doi.org/10.1021/acs.accounts.2c00232 [ii] Nelson et al., (2022), Nature Communications, 13(1), 5691. [iii] Zumstein et al., (2018), Sci. Adv. 2018;4: eaas9024

Spoken Language: English Category: Fundamental Research: Bio-Surfactants Phospholipid (PL) liposomes are of central importance in pharmacology and cosmetics. Typically, they are obtained by injecting a concentrated ethanolic PL solution (or other alcohol) into water. Subsequent application of shear reduces the liposome size and makes them colloidally stable. After injection, lipids and actives interact with solvent molecules prior to alcohol removal. In this regard, an interesting observation was made when trying to remove ethanol from a PL dispersion by “fast ultrafiltration” (5x doubling the concentration followed by addition of water to return to the original concentration, all within one hour) that hardly removed any ethanol. However, by taking more time or doing dialysis overnight, EtOH-removal was almost complete. Thus, we wondered to which extent alcohols could associate with the fluid bilayer, so that no fast alcohol removal was possible. To this end, we studied the influence of short-chain alcohols (methanol, ethanol at ≥10%w) on PL liposomes and compared their effect with that of butanol, a well-known co-surfactant. We see an overall tendency of reduced particle size in the presence of alcohols by light scattering. Moreover, from model-free analysis of small-angle neutron scattering (SANS) curves, we see evidence of solvent (water + alcohol) incorporation into the bilayer, where the solvent constitutes ~20% of the bilayers. Additionally, we observe that the alcohols reduce the stiffness of the bilayer from neutron spin-echo (NSE) experiments. Finally, we analyze the effect of glycerol, a potential alternative to primary alcohols for the formation of liposomes. Unlike the other organic solvents, glycerol hardly affects liposome particle size, induces bilayer stiffening and does not seem to penetrate into the bilayer core. Understanding how alcohols at high concentrations interact with phospholipids will render essential information to develop more stable, green and functional liposome formulations.

Spoken Language: English Category: Fundamental Research Polymers with stimuli-responsive properties have attracted substantial research interest in the past years, as they offer a multitude of possibilities to create functional materials that undergo structural and physicochemical changes under applied external stimuli, such as temperature or hydrostatic pressure. One of the central research interests is to understand how small molecular penetrants (such as drugs, toxins, and reactants) permeate through hydrated polymer membranes. While the properties of swollen hydrogels are nowadays relatively well understood, the collapsed, weakly hydrated states pose a significant challenge to our understanding. Namely, their theoretical description is complicated owing to the enormous role that molecular architecture plays. Yet, precisely this architecture-specific feature gives low-hydrated polymers the ability to be highly selective and favor the passing of specific molecules over others. Our molecular simulations reveal that polymer materials with low water content exhibit a highly heterogeneous interior with water clusters resembling nanodroplets and nanochannels. We demonstrate that the two critical quantities for transport, the molecular diffusion and the solvation free energy inside the polymer, are extremely sensitive to molecular details of the water clusters, penetrant size, shape, and chemistry, leading to vast cancellation effects, which nontrivially contribute to the permeability. We highlight the significance of water droplet interface potentials and the nature of hopping diffusion through transient water channels. These mechanisms can be harvested and tweaked to optimize selectivity in molecular transport in various applications.

Spoken Language: English Category: Fundamental Research The ubiquitous contamination of the environment with microplastics (MP) and the associated potential risks perpetually attracts a great deal of public, political, economic, and scientific attention. However, the problem is very complex, as MP represents a very heterogeneous group of particles with a wide range of chemical and physical properties, which also constantly change due to various environmental impacts and the resulting aging processes. This can lead to altered environmental behavior as well as to different biological effects. The goal of SFB 1357 is therefore to gain a fundamental understanding of the processes and mechanisms that condition biological effects of MP in limnetic and terrestrial ecosystems as a function of the physical and chemical properties of the particles, influence the migration behavior of MP particles and cause the formation of MP starting from macroscopic plastics. These findings provide a scientifically sound basis for assessing the environmental risks of MP, as well as for developing environmentally friendly plastics and processes to prevent the emission of MP into the environment.

Spoken Language: English

Spoken Language: English

Spoken Language: English Category: Fundamental Research Water-soluble polymers (WSPs) have a wide range of applications, including in home and personal care products. After use, WSPs often end up in wastewater systems, making biodegradability in these systems an important property for many WSPs. However, our understanding of how microbiomes in wastewater systems biodegrade WSPs is limited, and current testing guidelines for biodegradation of chemicals, including polymers, were developed for small molecules and may need to be adapted for studying polymer biodegradation. One important step in the biodegradation of polymers is the breakdown of large molecules into small ones that can be taken up by cells. This step can be catalyzed by extracellular enzymes. In this talk, I will present our ideas and results regarding the above-mentioned knowledge gaps. We studied the biodegradation of selected WSPs (with a focus on polyamino acids) using incubation experiments coupled to respirometric analysis. Thereby, we focused on the effect of (i) WSP pre-incubation with cell-free wastewater extracts, which were conducted to mimic fate in sewer systems, (ii) pre-aeration and washing of the microbial inoculum, which is typically done to reduce background signals but might reduce the activity of extracellular enzymes, and (iii) WSP concentration on biodegradation dynamics. Our results provide promising insights into WSP biodegradation by wastewater microbiomes and can inform the development of biodegradable WSPs and testing protocols for realistic and feasible biodegradation studies.

Spoken Language: English Category: Fundamental Research The self-assembly of oppositely charged polyelectrolytes and surfactants leads to polyelectrolyte-surfactant complexes (PESCs) with widely variable structure and properties. In particular, the rheological properties may vary largely between low viscous systems formed by isolated complexes to highly viscous or gel-like systems containing a highly interconnected network structure. In this context we studied complexes formed by polydiallyldimethylammonium chloride (PDADMAC) or cationically modified hydroxyethyl cellulose (JR 400) with anionic surfactants like sodium dodecylsulfate (SDS). These experiments show a markedly different behaviour that depends on the choice of the polycation. However, even more interestingly we observe a very high sensitivity of the rheological properties to the addition of medium-chain alcohols as cosurfactants. With already rather small added amounts of ~0.1 wt% cosurfactant the zero-shear viscosity can become enhanced by more than 3 orders of magnitude, with a corresponding appearance of viscoelastic properties. The precise extent of viscosity enhancement depends markedly on the type of medium-chain alcohol employed, and, of course, on the amount added. With a combination of static and dynamic light scattering and especially small-angle neutron scattering (SANS) we were able to elucidate the structural differences arising from the addition of cosurfactant, as well as the role played by the polyelectrolyte in forming PESCs. Both components determine the mesoscopic structure and the different rheological behaviour arising from it. In summary, we can deduce a systematic correlation between the mesoscopic structure of the cosurfactant containing PESCs and their rheological properties, which depends pronouncedly on the molecular details of the systems components. This then is not only of fundamental interest, but also central to the ration formulation of polymer/surfactant systems, in which rheological control is important.

Spoken Language: English

Spoken Language: English Category: Fundamental Research Unique properties of microgels like porous structure, chemical functionality, surface-activity and adaptability to different solvents, make them extremely attractive colloidal carrier systems for application in catalysis, emulsion stabilization and drug delivery. Open microgel structure and the presence of functional groups provide the possibility to attach selectively enzymes and to control their localization at the surface or in the interior. The porous structure of the microgel also allows diffusion of small molecules (reagents, solvents) and the diffusion rate can be regulated by the stimuli-triggered degree of swelling of the polymer network. Microgels can adapt to different environments, stabilize interfaces and are easily reversibly transferred from water to organic solvents. This contribution will focus on general properties of microgels, their synthesis with controlled chemical composition, size, swelling degree and distribution of functional groups. Several synthesis methods for the encapsulation of enzymes in microgels will be discussed including: a) enzymatic polymerization; b) crosslinking in W/O emulsions, c) diffusion-based loading and d) Sortase-mediated conjugation. The biggest challenge is to achieve the high enzyme loading along with high enzyme activity. The encapsulation of enzymes in microgels allows flexible regulation of their activity and improvement of storage stability. The incorporation of enzymes into stimuli-responsive microgels provides functional colloidal building blocks for the fabrication of adaptive biocatalysts, biosensors or synthetic biofilms.

Spoken Language: English Category: Fundamental Research Regulations world-wide are rapidly developing for polymeric materials. One of the key concerns underpinning the use of polymers are their uncertain environmental biodegradability. This has put an increasing emphasis on the need to identify, and critically evaluate testing guidelines for assessing biodegradability to determine their applicability and limitations for polymeric materials. In reviewing the numerous biodegradation testing guidelines, several methods have been identified that in principal, may be used to assess biodegradability of soluble and poorly soluble polymeric materials. Screening level methods such as OECD test guidelines (e.g., 301/310) for biodegradation have been developed primarily for soluble or poorly soluble low molecular weight substances. On the other hand, media-specific methods such as ISO (e.g., 14852) and ASTM test guidelines (e.g., 5988) have focused on insoluble plastic materials. These methods have some commonalities such as reliance on non-specific analyses (i.e., O2 consumption, DOC and CO2) and offer some level of flexibility regarding inoculum type and concentration and test substance dose level. Unfortunately, systematic investigations about their applicability for polymers are lacking and limited publicly available data are currently available. Questions related to their inter and intra-laboratory variability, suitable reference materials and degree of stringency remain. In view of the extremely dynamic regulatory atmosphere, these knowledge gaps need to be urgently filled. In this study we present the groundwork of an interlaboratory study investigating the applicability of OECD and ASTM methods focusing on respirometric end points to study biodegradability of water-soluble polymers. A set of synthetic polymers and modified polysaccharides have been used as case studies. Sewage sludge and river water have been selected as inoculum for the studies. Future work will include evaluating poorly soluble polymers, further exploring inoculum effect and identifying suitable reference materials. Modifications of the existing standards to improve method deficiencies is an expected product of this effort.

Spoken Language: English Category: Fundamental Research Surfactants are an important component of the chemical industry and are used in many economic sectors. From cleaning agents to auxiliary materials for chemical reactions, such as emulsion polymerisation, there are almost no limits to these surface-active substances. In 2016, a total of approximately 1.29 million tonnes of surfactants were produced in Germany for applications in households and industrial processes. Of these, 1.10 million tonnes are cationic, anionic and non-ionic surfactants [1]. About 41 % is accounted for by non-ionic surfactants alone, of which a significant proportion is produced from long-chain fatty alcohols and ethylene oxide (EO). With a sales value of 894 million euros, non-ionic surfactants are among the most important chemical products [1,2]. A modern way to make them more ecological is to use CO2-containing surfactants. Producing them and at the same time controlling the product properties is possible by using a CO2 building block such as cyclic ethylene carbonates (cEC). If one understands the control parameters of the ring-opening polymerisation and thus the understanding of the control parameters of a ring-opening polymerisation of cyclic ethylene carbonates (cEC), one can produce functional non-ionic surfactants that are both environmentally friendly due to good biodegradability and that are recyclable. For example, these surfactants have already been proven to purify microplastic contaminants from water [3]. [1] Statistisches Bundesamt, Statistisches Bundesamt Produzierendes Gewerbe, 2016. https://www.destatis.de/DE/Publikationen/Thematisch/IndustrieVerarbeitendesGewerbe/Strukturdaten/Kostenstruktur2040430107004.pdf?__blob=publicationFile. [2] M. Patel, A. Theiß, E. Worrell, Surfactant production and use in Germany: resource requirements and CO2 emissions, Resour. Conserv. Recycl. 25 (1999) 61–78. https://doi.org/10.1016/S0921-3449(98)00063-9. [3] D. Brüggemann, T. Shojamejer, M. Tupinamba Lima, D. Zukova, R. Marschall, R. Schomäcker, The Performance of Carbonate-Modified Nonionic Surfactants in Microplastic Flotation, Water. 15 (2023) 1000. https://doi.org/10.3390/w15051000.

Spoken Language: English Category: Fundamental Research Sophorolipid biosurfactants are truly green, natural, non-fossil, fermentation-derived, mild surfactants, with additional functionalities such as antibiofilm and moisturising properties. Given this, the commercial interest in biosurfactants is rising rapidly. Made from fermentation, biosurfactants are a sustainable replacement for petrochemical-derived surfactants and with favourable characteristics for personal care, home care and agriculture. Major formulators have made strong commitments to expand their green product portfolio. However, these have never been fully realised in mass market applications until now due to the high sales price. Using interdisciplinary research, we created and scaled up a cheaper, but also a more sustainable production method for sophorolipids. Our patented technology is a plug and play system that can be used to increase output from a given bioreactor 3-4x, which enables the reduction of production costs by over 50%. We have scaled this technology and commercialised sophorolipids from lab to pilot and have built the first manufacturing plant in at 1.1ktpa scale, all in less than 5 years. A life cycle assessment (LCA) shows up to 70% improvement on­ CO2 Global Warming Potential per tonne active product compared to petrochemical surfactants. We present our innovative technology, the sophorolipid properties, the data to prove it is an environmental improvement and our rapid and successful scale-up journey. We will also go over our strategy to reach Net Zero, including process optimisation, sidestream valorisation, carbon capture and feedstocks upcycling; therefore demonstrating the potential of fermentation for platform technology of new sustainable bioproducts.