Laboratory 6.2 “Disperse systems and rheology in clean technologies” within WP 6 “Nano-structured materials and disperse systems in clean technologies” aims at the development of new systems for clean technologies and nanotechnologies in various scientific and technological areas: new cleaning agents for hard surfaces; encapsulation and controlled release of reagents; wetting and dewetting processes. The main objectives are to conduct experimental and theoretical research and development of new dispersed systems through the inclusion of new raw materials and innovative materials, and to develop and apply theoretical models of the interactions and stability of complex dispersed systems. High scientific output of Lab 6.2 is manifested via 21 scientific publications in the fields of Dispersion Chemistry, Chemical and Materials Sciences for the period 2018 – 2024 (8 articles in Q1 journals, 6 in Q2, and 7 materials in Q4). Optimized compositions of cleaning formulations for hard surfaces with sulfonated methyl esters have been obtained [1]. New theoretical models for the interactions that determine the structures in micellar systems have been developed and applied [2]. New phenomena such as vortexing [3] and nanoemulsification [4] have been described. New methods have been proposed for obtaining emulsions and foams from triglyceride phases [5]. The role of the components and compositions for the rheology [6], wetting, and cleaning [7] has been demonstrated.

The research paper explores the ability of isolated multiconnected micellar phases (MMP) to remove different soils (dimethicone, sebum oil, and makeup formulations) from artificial skin. The MMP is isolated from 3 wt% 1:1 sodium lauryl ether sulfate with 2 ethylene oxide group + cocamidopropyl betaine in the presence of 62 mM MgCl2. The direct observations of soil removal demonstrate the efficacy of the MMP by two physicochemical mechanisms. For dimethicone soils, the roll-up mechanism is observed, i.e. shrinkages of the drop contact areas and decrease of the three-phase contact angles due to the changes in the interfacial tension and the surface energy. For sebum soils, the spontaneous emulsification mechanism takes place because of the mixing of the fatty acids present in the sebum with the surfactants and forming complex amphiphilic structures. For makeup formulations, the new approach based on the software image analysis by means of Image J is developed to account for the whole soiled area and to increase the precision of the quantitative cleaning characterization. The obtained results show that the bicontinuous phase successfully removes dimethicone, sebum oil, and foundation soils from the artificial skin and could have potential application in the design of new personal, home and industrial care products.

Kappa carrageenan (KC), a sulfated polysaccharide derived from red seaweed, exhibits distinct gelation properties that are influenced by ionic strength and thermal conditions. While its behavior in aqueous media is well-established, understanding KC’s gelation mechanisms in non-aqueous solvents (like glycerol) remains limited. This study investigates the conformational and rheological properties of kappa carrageenan in glycerol, focusing on the effects of sodium salts (NaCl, NaH2PO4, Na3PO4) at varying concentrations and preparation temperatures (60 °C and 80 °C). Rheological measurements reveal distinct viscosity trends influenced by salt type and temperature, highlighting the interplay between ionic interactions and KC’s conformational transitions. Phosphate salts significantly enhance network elasticity and stability, especially at intermediate concentrations, whereas NaCl induces weaker, viscosity-dominated structures. Atomic force microscopy imaging provides complementary nanoscale insights, showcasing salt-specific structural transitions from looped to branched networks, alongside a temperature-dependent helix-to-coil transformation. These results illustrate how the precisely tuning ionic conditions and the preparation temperatures in glycerol media can effectively modulate KC’s structure and viscoelastic properties. This deeper understanding facilitates targeted design and optimization of carrageenan-based materials across food, pharmaceutical, cosmetic, and biotechnological applications.

A systematic study on the mechanisms of cleansing artificial skin by solutions of widely used in personal care surfactants disodium laureth sulfosuccinate (DSLSS), sodium laureth sulfate (SLES), sodium dodecyl sulfate (SDS), dodecyl trimethyl ammonium bromide (DTAB), and coco glucoside (CG), is presented. The systematic characterization of soil removal from artificial skin revealed two primary cleansing mechanisms: emulsification and roll-up. Emulsification occurs in systems with very low interfacial tension, such as sebum in SLES solutions, while dimethicone soil was only removed by roll-up. The roll-up effectiveness depends on the surfactant’s interfacial activity and its adsorption on the soiled surface. Thus, the strong adsorption of DTAB on the skin leads to dimethicone roll-up at a relatively high interfacial tension of 11 mN/m. The anionic and nonionic surfactants adsorbed less at the artificial skin surface, and the oil/water interfacial tension value lowering below 5 mN/m is necessary for the roll-up to occur. Nonionic CG removed dimethicone at a lower concentration than ionic surfactants. Combining CG with ionic surfactants improved cleaning at lower total concentrations. Surfactant mixtures are used to formulate simple cleansing formulations, whose performance is also investigated by the developed in vitro approach. The results obtained allow for a good rating of the formulations, which correlates well with the performance of the surfactant mixtures and their interfacial activity.

The class of volatiles, which possess low saturated vapor pressures, appreciable solubilities in water, and well pronounced surface activities, have gained wide applications in diverse areas of industry, cosmetics, and medicine. One way to qualitatively characterize their mass transfer between vapor and aqueous solutions is to measure the relaxation of the interfacial tension, σ, with time, t, under different nonequilibrium initial conditions. This approach is applied in the present work for geraniol and menthol. By means of combining σ(t) data with the respective equilibrium surface tension isotherms, the instantaneous values of the fragrance adsorption, Γ(t), have been determined. Quantitative characterization of the geraniol and menthol mass transfers in the case of adsorption from vapor to aqueous drops is achieved by using a mixed barrier-diffusion model. The obtained values of the rates of adsorption and desorption are compared with those reported in the literature for benzyl acetate, linalool, and citronellol. In the case of evaporation of the volatiles from their saturated aqueous solutions to the ambient atmosphere, the mass transfer is found to be driven both by mixed barrier-diffusion and by convection-enhanced mechanisms – depending on the air humidity. The quantitative description of the evaporation of volatile molecules is modelled theoretically by adsorption rate constants. In order to achieve the reported model representations, complex numerical calculations are implemented. On the other hand, having in mind the cases when one wishes to avoid extensive computational work, we developed a simple semiempirical model suitable for all five studied fragrances. This simplified approach is convenient for the express comparison and characterization of the evaporation rates. The obtained physicochemical parameters related to the evaporation and condensation of volatiles are important for the rigorous modeling of their complex mixed solutions of practical interest. The semiempirical model could be used for the quantitative classification of volatile molecules with respect to their ability to evaporate.