Abstracts: Scientific Poster Session

Main Auditorium, Wednesday, 12 October 2016

12:45 – Short Introduction of Scientific Posters by Authors
17:45 – Scientific Poster Session with Authors
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>> 1. Tuning the Pore Wall Thickness of Monodisperse Polymer Foams

>> 2. Household Dishwashers in Germany – Evaluation of the Hygienic Conditions
and Qualitative & Quantitative Analysis of the Microbial Communities

>> 3. Raft Formation of the Saponin Escin in Small Unilamellar
1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) Vesicles

>> 4. Surface Activity of Modified Bioplolymers

>> 5. Bicontinuous Microemulsions and Macrogels
as Model Systems for Anomalous Diffusion

>> 6. Small-angle Neutron Scattering Study on the Incorporation of Escin in Small
Unilamellar 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) Vesicles

>> 7. Incorporation of Escin, Ibuprofen and Cholesterol in small unilamellar
1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) vesicles

>> 8. Microbial Synthesis, Derivatization and Characterization
of Sophorolipid Type Biosurfactants

>> 9. Does the Pore Size have an Impact on the Mechanical Properties
of a Monodisperse, Ordered Polystyrene Foam?

>> 10. Microfluidic-assisted Generation of Monodisperse,
Highly Ordered, and Biobased Porous Polymers

>> 11. New Experimental Technique for Studies with Single Pseudo Emulsion Films

>> 12. Physicochemical Characterization of Sulphonated Methyl Esters
(Palmfonate) via “Computer” Purification Approach

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1. Tuning the Pore Wall Thickness of Monodisperse Polymer Foams

Aggeliki Quell¹, Wiebke Drenckhan², Cosima Stubenrauch¹
(¹ Institute of Physical Chemistry, University of Stuttgart, Germany
² Laboratoire de Physique des Solides, CNRS, Université Paris-Sud,
Université Paris-Saclay, Orsay, France)
The principle of emulsion templating is to generate an emulsion and to retain its structure during polymerization. This leads to polymer foams whose pore size correlates with the droplet size of the emulsion template. Especially high internal phase emulsions (HIPEs) are of great interest because they lead to low density polymer foams [1]. To date most emulsions are generated via agitation, resulting in a highly polydisperse template the polymerization of which leads to highly polydisperse polymer foams [2-4]. We recently showed that water-in-styrene HIPEs can also be generated with microfluidic lab-on-a-chip techniques, which, in turn, leads to monodisperse polymer foams [5]. In the work at hand, we show how the pore morphology of crosslinked polystyrene foams can be fine-tuned without changing the pore size itself by varying parameters such as the surfactant concentration, the emulsion height, the initiation temperature as well as the locus of initiation [6].

[1] D. Barby, Z. Haq (Unilever PLC), EP 0060138, 1982.
[2] J. M. Williams, D. A. Wrobleski, Langmuir 1988, 4, 656.
[3] N. R. Cameron, Polymer 2005, 46, 1439.
[4] G. Ceglia, et al. Eur. Phys. J. E 2012, 35, 31.
[5] A. Quell, J. Elsing, W. Drenckhan, C. Stubenrauch, Adv. Eng. Mater. 2015, 17, 604.
[6] A. Quell, B. de Bergolis, W. Drenckhan, C. Stubenrauch, Macromolecules 2016, in press.
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2. Household Dishwashers in Germany – Evaluation of the Hygienic Conditions
and Qualitative & Quantitative Analysis of the Microbial Communities

Britta Brands and Prof. Dr. Dirk Bockmühl
(Rhine-Waal University of Applied Sciences, Kleve, Germany)
In domestic dishwashing there is an ongoing trend towards lower temperatures and reduced water consumption. This trend is supported by types of dishwashers that consume less water or apply lower temperatures in the final rinse cycle. The hygiene level of these appliances and the impacts of the changed consumer habits were investigated in two studies. The first study investigated dishwashers in German households to analyze the microbial communities and their putative impact on dishwashing hygiene. Although several consumer related parameters, such as cleaning frequency, downtime or age of the dishwasher were considered likely to have an impact on the hygienic status of the dishwasher, it turned out that there is no clear relation between single parameters and the microbial colonization. In contrast it must be assumed that the hygienic quality of dishwashers is influenced by many factors. In terms of reduced temperatures and water consumption the hygienic quality of cleaned dishes and appliances must still be considered good although these parameters have to be carefully observed in the future, for example, when temperatures are being further decreased.
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3. Raft Formation of the Saponin Escin in Small Unilamellar
1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) Vesicles

Carina Dargel¹, Ramsia Sreij¹, Jaqcues Jestin², Thomas Hellweg¹
(¹ Physical and Biophysical Chemistry, Department of Chemistry, Bielefeld University, Germany; ² Laboratoire Léon Brillouin, Gif sur Yvette Cedex, France)
Phospholipids show an emulsifying effect and are therefore widely used as food additives and pharmaceutical excipients. 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) belongs to the class of phospholipids and acts i.a. as a major membrane component. Therefore, model membranes consisting of DMPC mimic biological membranes quite well and allow to study effects of additives under different conditions, e.g. composition and temperature. Because of the hydrophobicity of the inner part of the lipid membrane, small and mostly hydrophobic molecules such as cholesterol incorporate into these membranes, whereby the membrane properties like the fluidity are changed.
Another class of molecules, strongly interacting with lipid membranes, are saponins. These exhibit an amphiphilic structure built of a hydrophobic steroidic or triterpenic backbone with a varying number of hydrophilic sugar chains and therefore also show an emulsifying effect. Because the interaction of saponins with (biological) membranes is not scrutinized the effect of the saponin escin on small. unilamellar vesicles of DMPC was investigated by different methods, for instance scattering and calorimetry. Below a limiting concentration escin only attaches to the vesicles surface but gets incorporated above this concentration. When incorporated, the escin molecules arrange temperature dependently into rafts, similar to cholesterol.
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4. Surface Activity of Modified Bioplolymers

Michelle Tupinamba Lima¹, Reinhard Schomäcker¹,
Michael Schwarze¹, Brigitte Olschewski², Oliver Roeber²
(¹ Technical University of Berlin, Germany,
² Faliten GmbH, Berlin, Germany)
From protein-rich biomass such as yeast, and various vegetable oils, surface active agents can be prepared by a condensation reaction. So far there is no exact information on the chemical structure and possible mechanism of action associated with these products.
Ultrafiltration measurements of the solutions showed that only a small fraction of the products consist of low molecular weight compounds while a predominant part consists of macromolecules, what was also proven by DLS.
The majority of the biological building blocks (amino acids, fatty acids and sugars) from the starting materials are not destroyed during the condensation reaction, but only rearranged.
The structure of this modified denatured protein forms the basis for ensuring that the molecules self-aggregate and absorb at interfaces.
The aggregation behaviour in aqueous solution can easily be obtained from electrical conductivity measurements. The critical micelle concentrations determined from these measurements (CMC < 1g/L) are consistent with those that were determined from measurements of the surface tensions. The CMC of the product can be varied either by varying the proportion of oil in the synthesis recipe or by using other vegetable oils. Experiments for foam characterization in a shaking test and using a film balance show that the foams are very stable and electrostatically stabilised. Their very low CMC and high foam stability are advantageous for heavy dirty cleaning and foam flotation.
Experiments on the adsorption at solid surfaces show no saturation behaviour, indicating "multi layered adsorption", favourable for many applications.
For comparison with other surfactants the products were assigned with a HLB value by comparison of octanol-water partition coefficient with those from known surfactant. This analogy gives values between 40 and 50 which mean the products are very hydrophilic, comparable to short chain alkyl sulphates.
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5. Bicontinuous Microemulsions and Macrogels
as Model Systems for Anomalous Diffusion

Oliver Wrede and Thomas Hellweg
(Physical and Biophysical Chemistry, Faculty of Chemistry, Bielefeld University, Germany)
The translational motion of particles in confining environments, such as living cells or artificial membranes, can differ from the normal Fick type diffusion, where the mean square displacement grows linear in time, but is considered 'anomalous' [1,2,3]. To establish a theoretical description, an insight into the diffusive behavior of particles (e. g. proteins, fluorescent dyes) under confining conditions is crucial.
To resolve the dependence of the tracer particle diffusion on the confinement, we studied the dynamics of different fluorescent particles (GFP+, Atto655 and Atto647N-dextran-conjugates) in systems which mimic cellular environments (bicontinuous microemulsions and macrogels) via fluorescence correlation spectroscopy. In the microemulsion case the size of the confining sponge like network was tuned over a range of several nanometers by changing the composition of the microemulsions [4] and characterized via small angle scattering. For the macrogels tracer particles with different sizes were used in gels with different cross linker content and therefore smaller mesh sizes.
For macrogels 'Fickian' diffusion is preserved for all fluorescent dyes and all cross linker contents accessible with FCS. The microemulsions on the other side change the diffusive behavior from 'Fickian' to 'anomalous' in a linear way (Figure 1). This leads to the assumption, that confinement (like a crowded environment) is not the singular cause for anomalous diffusion, but the forced interaction with a surfactant layer plays a role as well.


[1] T. J. Feder, I. Brust-Mascher, J.P. Slattery, B. Baird, W. W. Webb, Biophysical Journal 1996, 70, 2767-2773.
[2] E. O. Potma, W. P. d. Boeij, L. Bosgraaf, J. Roelofs, P. J. van Haastert, D. A. Wiersma, Biophysical Journal 2001, 81, 2010-2019.
[3] M. Weiss, M. Elsner, F. Kartberg, T. Nilsson, Biophysical Journal 2004, 87, 3518-3524.
[4] T. Sottmann, R. Strey, S.-H. Chen, The Journal of Chemical Physics 1997, 106, 6483-6491.
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6. Small-angle Neutron Scattering Study on the Incorporation of Escin in Small
Unilamellar 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) Vesicles

Ramsia Sreij, Carina Dargel, and Thomas Hellweg
(Physical and Biophysical Chemistry, Faculty of Chemistry, Bielefeld University, Germany)
Lipid membranes are key objects in industrial and pharmaceutical research in relation to interaction of e.g. drugs with membranes, membrane-bound receptors and drug targeting, penetration and permeation of cell membranes as well as the use of liposomes for drug delivery and transport. Detergents are indispensible components which serve as solubilizing agents in the isolation, purification and reconstitution or crystallization of membrane bound proteins. In much lower concentrations, these detergents serve as useful agents to permeabilize or to perturb membrane structures [1]. Industrial applications e.g. in the detergents manufactory require deeper understanding of physical properties of lipid membranes and the changes in the bilayer properties resulting from interactions between incorporated molecule and membrane. The function of membrane bound proteins depends on the bilayer relevant size parameters and its properties. In the present contribution we study the properties of the lipid bilayer in model membrane systems in form of unilamellar vesicles (ULVs) consisting of the phospholipid 1,2-dimyristoyl-sn-glycero-3-phospho-choline (DMPC) in the presence of the saponin Escin. Saponins are a divers class of natural, plant derived amphiphilic molecules with a peculiar molecular structure made of a hydrophobic scaffold and hydrophilic oligosaccharide chains. Escin is a very pure chemical product allowing us to study and to assign the interactions of saponin molecules with the lipid membrane. These molecules have strong surface activity and are used as natural emulsifiers and foaming agents in food, pharmaceutical or other industries. The main feature of saponin molecules incorporating into the membrane of living cells is the formation of insoluble complexes with cholesterol molecules and thus the reduction of the cholesterol bioaccessibility by displacement of cholesterol molecules from the bile salt micelles. The effect of the Escin incorporation into small unilamellar vesicles is studied by small- angle neutron scattering (SANS) (See Fig.1) below and above the main phase transition temperature of DMPC. The incorporation of Escin shows a significant effect on the form factor of DMPC.


Fig. 1 SANS curves of incorporated Escin in DMPC vesicles.

[1] Andersen et al., Eur. J. Biochem., 134 (1983), 205-214.
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7. Incorporation of Escin, Ibuprofen and Cholesterol in small unilamellar
1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) vesicles

Ramsia Sreij, Carina Dargel, and Thomas Hellweg
(Physical and Biophysical Chemistry, Faculty of Chemistry, Bielefeld University, Germany)
Lipid bilayer membranes are key objects in industrial and pharmaceutical research in relation to interaction of e.g. drugs with membranes, membrane-bound receptors and drug targeting, penetration and permeation of cell membranes as well as the use of liposomes for drug delivery and transport. Detergents are indispensible components which serve as solubilizing agents in the isolation, purification and reconstitution or crystallization of membrane bound proteins. In much lower concentrations, these detergents serve as useful agents to permeabilize or to perturb membrane structures [1]. Industrial applications e.g. in the detergents manufactory require deeper understanding of physical properties of lipid membranes and the changes in the bilayer properties resulting from interactions between incorporated molecule and membrane. The function of membrane bound proteins depends on the bilayer relevant size parameters and its properties. In the present contribution we study the properties of the lipid bilayer in model membrane systems in form of unilamellar vesicles (ULVs) consisting of the phospholipid 1,2-dimyristoyl-sn-glycero-3-phospho-choline (DMPC) in the presence of saponins, cholesterol and ibuprofen. Saponins are a divers class of natural, plant derived amphiphilic molecules with a peculiar molecular structure made of a hydrophobic scaffold and hydrophilic oligosaccharide chains. They have strong surface activity and are used as natural emulsifiers and foaming agents in food, pharmaceutical or other industries. Their incorporation into the membrane of living cells reduces the cholesterol bioaccessibility by displacement of cholesterol molecules from the bile salt micelles. Here, we use the nearly pure saponin Escin. The effect of the Escin incorporation into small unilamellar vesicles is studied by various techniques including small- and wide-angle X-ray scattering (S/WAXS), small- angle neutron scattering (SANS), dynamic light scattering (DLS), turbidity measurements and differential scanning calorimetry (DSC) (See Fig.1). The incorporation of Escin shows a significant decrease of Tm above an incorporated mole fraction of 1.5 mol%. Further raft formation similar to cholesterol was observed. While the incorporation of cholesterol shows an increasing bilayer thickness upon increasing mole fraction, the incorporation of ibuprofen leads to reduced bilayer-specific parameters.


Fig.1: DSC curves of Escin, ibuprofen and cholesterol loaded DMPC vesicles.

[1] Andersen et al., Eur. J. Biochem., 134 (1983), 205-214.
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8. Microbial Synthesis, Derivatization and Characterization
of Sophorolipid Type Biosurfactants

Yifei Zhan, Sonja Müller, Ulrich Schörken, Birgit Glüsen
(Technische Hochschule Köln, Fakultät für Angewandte Naturwissenschaften,
Leverkusen, Germany)
Sophorolipids are commercially available low-foaming biosurfactants, which are composed of the disaccharide sophorose (1,2-linked glucose dimer) esterified with two molecules acetic acid and linked to a hydroxylated fatty acid. They can be produced from Starmerella bombicola and related yeasts in large quantities by feeding sugar and oil simultaneously. Depending on the yeast strain utilized the hydroxylation pattern of the resulting sophorolipid and the lactonic to open chain ratio can differ. Though a strong preference for incorporation of C16 and C18 hydroxy-fatty acids exists, varying the lipid substrate influences the sophorolipid tail to some extent. Further sophorolipid modification can be obtained in one-step derivatizations like esterification of the fatty acid moiety with short chain alcohols or alkaline hydrolysis of the lactonic ring form resulting in deacetylated anionic surfactants with higher foaming potential.
Synthesis and initial characterization of sophorolipids from different yeast strains on the basis of varying lipid substrates is presented. Comparative submerged fermentations were carried out e.g. with liquid unsaturated and solid saturated fatty acids and the sophorolipids were recovered by extractive processing. Additionally ring opening modifications were carried out and the structurally differing sophorolipid mixtures were characterized concerning their ability to reduce the surface tension of water and their foaming characteristics. The physicochemical data were compared to commercially available bio-based surfactants of the glycolipid type.
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9. Does the Pore Size have an Impact on the Mechanical Properties
of a Monodisperse, Ordered Polystyrene Foam?

Jonas Elsing¹, Cosima Stubenrauch¹, Michael Gilchrist², Wiebke Drenckhan³
(¹ Universität Stuttgart, Germany; ² University College Dublin, Ireland;
³ Université Paris Sud, France)
Polymer foams have a wide range of applications. They may serve as impact protection, insulation or packaging materials [1]. One of the most frequently used polymer foams is expanded polystyrene. The high complexity of traditional manufacturing processes makes it difficult to control the structure and porosity of the material. Here we show a route for the synthesis of monodisperse ordered polystyrene foams via a microfluidic device. Pure styrene cannot be foamed, even in the presence of surfactants. This problem is solved by foaming a styrene-in-water emulsion with a high styrene content of 64.5 vol% [2] where the surfactant stabilizes both the styrene droplets as well as the gas bubbles. Foaming is carried out by means of a microfluidic device with flow focusing architecture which allows the generation of a monodisperse foam. The foamed emulsion remains stable during the polymerization and the structure of the liquid foam is retained. We here show that this technique allows controlling the pore size of the polymer foam by adjusting the bubble size in the liquid foam. Moreover, we show first results on the mechanical behavior of monodisperse, ordered polystyrene foams measured under compression and shear, respectively. The results indicate that the modulus is not correlated to the pore size but to the foam’s density.

[1] Mills, N., Polymer Foams Handbook, 2007.
[2] Schüler et al., Angew. Chem. Int. Ed., 51, 2213-2217, 2012.
[3] Quell, A., Elsing, J., Drenckhan, W., Stubenrauch, C., Adv. Eng. Mat., 17, 604-609, 2015.
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10. Microfluidic-assisted Generation of Monodisperse,
Highly Ordered, and Biobased Porous Polymers

Sébastien Andrieux¹, Wiebke Drenckhan², Cosima Stubenrauch¹
(¹ Institute of Physical Chemistry, University of Stuttgart, Germany;
² Laboratoire de Physique des Solides, University Paris-Saclay, France)
Monodisperse highly ordered porous polymers can be prepared using liquid templates generated via Lab- On-a-Chip techniques. A possible route consists in generating a liquid foam template[1-3] which is then solidified either by gelation or polymerisation, depending on whether the precursor in the liquid phase is a polymer or a monomer. Monodisperse liquid foams can self-organize under gravity and confinement leading to crystalline structures that may remain after solidification [4]. In a preliminary work microfluidics were used to generate a monodisperse hydrogel foam with the biopolymer chitosan. The drying of the hydrogel led to the respective solid foam [2]. We optimised this system by working solely with biobased compounds, namely the polymer chitosan, the surfactant Plantacare 2000 UP (an alkyl polyglycoside), and the cross-linker genipin (a molecule extracted from gardenia). We will present the different steps leading to monodisperse porous chitosan, starting with the formation of monodisperse bubbles and ending with the characterisation of the solid material. We will show how we manage to retain the structure of the template, namely by freeze-drying or by gelling the liquid template before it starts disintegrating. Such well-defined macroporous biobased polymer scaffolds might be used in a variety of applications, one of the most interesting being tissue engineering [5].

[1] A. van der Net et al., Colloids and Surfaces A 346, pp. 5–10, 2009.
[2] A. Testouri et al., Macromolecules 43(14), pp. 6166–6173, 2010.
[3] A. Quell et al., Adv. Eng. Mater. 17(5), pp. 604–609, 2015.
[4] W. Drenckhan, D. Langevin, Curr. Opin. Colloid Interface Sci. 15(5), pp. 341–358, 2010.
[5] F. Croisier, C. Jérôme, Eur. Polym. J. 49, pp. 780–792, 2013.
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11. New Experimental Technique for Studies with Single Pseudo Emulsion Films

Alexander Wilsdorf¹, Cosima Stubenrauch², Rumen Krastev¹ ³
(¹ NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany; ² Department of Physical Chemistry of Condensed Matter, University of Stuttgart, Germany; ³ Faculty of Applied Chemistry, Reutlingen University, Germany)
Different oil based composites are commonly used as "defoamer" or "antifoamer" to suppress the foaming in various processes where surface active substances are applied. Different mechanisms of defoaming action are discussed in the literature, but the mechanism of foam destruction is still not completely understood. The stability of the foams is controlled by the stability of the single liquid films which separate the gas bubbles in the foam – gas/liquid/gas foam films. The current theories describe the defoaming process as spreading, entry and bridging of the oil phase after the contact with the foam film [1]. Important event for the foam stability, respectively foam destruction, is the first contact of a foam film with the oil phase. At this moment an asymmetric pseudo emulsion gas/liquid/oil film is formed [2][3]. Studies with single pseudo emulsion films are not very common as the reproducible and easy formation of single films is not an easy task.
In this presentation we describe a new set-up for experiments with pseudo emulsion films. It is based on the well-established classical glass ring cell of Scheludko-Exerowa for studies with symmetrical foam films. The new set-up allows micro interferometric estimation of the film thickness, measurement of the film thinning velocity, assessment of the contact angle between the film and the bulk liquid phase and the stability of the single films.
Here we present the first results obtained with the new set-up. We measured the film thickness and the stability of the pseudo emulsion films in a wide range of electrolyte (NaCl) concentration and surfactant (sodium Alpha Olefin Sulfate) concentrations. Different model oils were tested. A good correlation with the results for the symmetric foam films is observed. Formation of very stable “dimples” in the films was observed at higher electrolyte concentrations (Figure 1) which stabilize the films [4][5].


Fig.1: Formation of a stable “dimple” during the formation of a thin pseudo emulsion film

Literature:
[1] N.D. Denkov, Mechanisms of foam destruction by oil-based antifoams, Langmuir. 20 (2004) 9463–9505. doi:10.1021/la049676o.
[2] V. Bergeron, C.J. Radke, Disjoining pressure and stratification in asymmetric thin-liquid films, Colloid Polym. Sci. 273 (1995) 165–174. doi:10.1007/BF00654014.
[3] D.T. Wasan, K. Koczo, A.D. Nikolov, Mechanisms of Aqueous Foam Stability and Antifoaming Action with and without Oil, (1994).
[4] T. Liquid, Experimental Investigation, 68 (1966) 3619–3624.
[5] J. Joye, C.A. Miller, G.J. Hirasaki, Dimple Formation and Behavior during Axisymmetrical Foam Film Drainage, 10 (1992) 3083–3092.
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12. Physicochemical Characterization of Sulphonated Methyl Esters
(Palmfonate) via “Computer” Purification Approach

P. Kralchevsky¹, K. Danov¹, R. Stanimirova¹, YS Lim², H. Xu²
(¹ Department of Chemical & Pharmaceutical Engineering, Faculty of Chemistry & Pharmacy, Sofia University, Bulgaria; ² KL-Kepong Oleomas Sdn Bhd, Research & Development ­Centre, Klang, Selangor, Malaysia)
Scientists and developers working in the home care field have been actively formulating sulphonated methyl esters (Palmfonate) in many commercial products. However, the scope of the applications can be broadened if there were more fundamental understanding on their physicochemical properties, such as surface tension, critical micelle concentration (CMC) and adsorption properties. Although there are efforts to present these properties, the data published often differ, sometimes, by order of magnitude in the CMC values because of the presence of nonionic admixtures (unsulphonated methyl ester). KLK OLEO is endeavouring to fully understand the properties and performances of Palmfonate. By cooperating with Sofia University, a ‘computer purification’ method was developed to determine these parameters of the ionic surfactant and the nonionic admixture without actual physical separation. This method involves fits of the surface tension and conductivity data by a physicochemical model based on a system of mass-balance, chemical-equilibrium and electric-double-layer equations. It is a quantitative characterization of Palmfonate, Cn-SME for n = 12, 14, 16 and 18 by determining their CMCs, surface tension isotherms and micellization, which further enable one to predict the adsorption, degree of counter-ion binding, surface electric potential, and effect of nonionic additives. For the first time, the systematic and quantitative study on the adsorption and micellization properties of Palmfonate has been achieved, which could become a basic reference. This is practically significant since it could allow customers to better understand the physicochemical properties of Palmfonate and the unintentionally associated nonionic admixtures, thus help them to formulate the final products.