Lucyna Hołysz

A series of multifunctional cationic surfactants comprising a tertiary amide linker in their structures and differing in their architecture, i. e. single head-single tail pattern with different hydrophobic tails ([(3-alkanoyilmethylamino)propyl] trimethylammonium bromides (CnBr, n = 12, 14 or 16)), as well as double head-double tail (gemini) analog (dimethyl{{3-[N-(3-{N-[3-(dimethylammonium)propyl] dodecylamido}propyl} dodecylamido}propyl}}ammonium dibromide (2xC12BrG3)) and double head-single tail (dicephalic) (N,N-bis[3,3′-(trimethylammonio)propyl]dodecanamide dibromide (C12(TAPABr)2)), both with the same alkyl chain length, were evaluated for their surface activity at the air/solution interface as well as wettability of the glass and/or polytetrafluoroethylene (PTFE) surfaces. The physicochemical behavior at the air–liquid interface was investigated. Surface tension isotherms of aqueous solutions of the studied multifunctional cationic surfactants were determined by pendant drop shape analysis and interpreted using the previously developed, in our group, modified surface quasi-two-dimensional electrolyte (mSTDE) model of ionic surfactant adsorption. The analysis was supported by the molecular dynamics simulations. The wetting properties of the above-mentioned surfactants were evaluated by measuring the advancing and receding contact angles of their aqueous solutions on bipolar glass and the advancing contact angle on apolar PTFE. Based on these results, the influence of surfactants on the surface free energy (surface tension) of water, glass, and PTFE was examined. It was found that changes in the surface free energies of water and glass depend on both the alkyl chain length and the structure of the surfactant molecules.

The paper describes the course of research on surface and interfacial phenomena as well as the obtained results, which were initiated by Professor Andrzej Waksmundzki in 1945 in the Department of Physical Chemistry and Electrochemistry organized by him at Maria Curie-Skłodowska University. It has been developed over the years and is still being developed today. The Research Group of Interfacial Phenomena and Flotation was established in the Department, which was at that time headed by doc. Jerzy Szczypa. Then, in 1997 the Department of Interfacial Phenomena was established and currently, because of the reorganization of UMCS it functions as the Department of Interfacial Phenomena at the Institute of Chemical Sciences. Initially, the Group Research was focused on the problems of mineral enrichment using the flotation and foam separation methods. This also involved the research on the wettability of various solids, their surface free energy and methods of its determination, both theoretically and experimentally by measuring contact angles. The research on the electric a double layer and electrokinetic phenomena was also carried out. There were applied also gas chromatography and adsorption methods, as well as modern equipment for examining surface properties of solids and liquids. Over the years, the scope of research on these phenomena has expanded to include superhydrophobic surfaces, the use of plasma for solid surface modification, investigations on layers of biologically active substances on various substrates, and biopolymer films in terms of their biocompatibility and use in pharmacy and medicine. The stability of dispersed systems and emulsions, as well as the influence of external fields (electric and magnetic) on the stability of dispersed systems in terms of the scale deposition were studied. In parallel, extensive research was carried out on the adsorption, aggregation and wetting properties of different surfactants, sugar surfactants, biosurfactants, their multi-component mixtures and those with organic additives such as short-chain alcohols, which being developed. The details of the research and its published results can be found in the extensive bibliography attached to the paper

Natural aggregates from sedimentary rock, like limestone and dolomite, are of a great use in various practical applications. To evaluate their quality, among others, the test of methylene blue adsorption (MB value) using a filter paper is recommended. However, one can consider it as a rough test. In this paper we wished to evaluate its quality by comparison with a more precise spectrophotometric method, i.e., to perform adsorption isotherms of methylene blue from aqueous solutions, as well as determine other parameters characterizing the aggregates. For this purpose, methylene blue adsorption on samples of limestone and dolomite natural aggregates having various grain sizes were studied to assess quality (fine particles content) of the manufactured aggregates. To determine the amount of adsorbed dye two methods were used: the methylene blue stain test and the dye adsorption from its solutions at various concentrations under static conditions. From the linear form of Langmuir adsorption isotherms of methylene blue, the monolayer capacity was determined, and then the specific surface areas of all fractions of aggregates. The structural (N₂adsorption/desorption), textural (SEM/EDS) and crystallographic structure of the aggregates were studied. It was determined that the MB values for 0–2 andMB_Ffor 0–0.125 mm aggregates fractions fulfill the criteria set out in the specifications required for pavement construction. A very good repeatability of the adsorbed amount of methylene blue on the dolomite and limestone aggregates were obtained by these two different methods. These results confirm the reliability of the method blue test used typically in industrial conditions. The measured specific surface areas of limestone and dolomite using N₂adsorption (S_BET) are smaller than S_MBdetermined by methylene blue adsorption from aqueous solutions. This is because in aggregates, apart from calcite and dolomite, there is a small admixture of quartz and clay minerals. During N₂adsorption in dry condition, the external surface of the grains is determined, while in the aqueous solution of methylene blue, both the external and inner surfaces of clay minerals are determined.

The magnetic field (MF) effects resulting from water or solution treatments are still of significant interest. However, a relatively small number of papers have been published dealing with the pure surfactant solutions alone. On the other hand, surfactants are applied in many industrial processes as well as in everyday life and are also present in different waste waters. Therefore, it seemed interesting to investigate whether some effects would appear after the MF treatment of pure aqueous surfactant solutions. In the earlier published papers after MF action the changes in water evaporation rate and the surface tension were found for both the cationic dodecyltrimethylammonium bromide (DTAB) and anionic sodium dodecyl sulfate (SDS) solutions. The gradient MF originated from three connected ring magnets inside which the solutions were placed. The objective of this paper is to study whether using the same magnets but in a different position the effects of the MF are observed. The given surfactant solution in a closed vessel was placed in an uniform MF when the magnets were in the “lying” position. The investigated solutions on the magnet surface remained for 24 h. In this paper, despite SDS and DTAB also the cationic hexadecyltrimethylammonium bromide (CTAB) and nonionic Triton X‐100 solutions were applied. It appeared that in the uniform MF the surface tension of cationic and anionic surfactant solutions changes. However, larger changes were observed in the gradient MF. Generally, the changes of surface tension depend on the surfactant kind and its concentration. Stronger MF influence was found for the cationic surfactant and almost no changes were observed for nonionic Triton X‐100.

Examples of nanostructured fluids (NSFs) used as highly specialized “brush‐on, wipe‐off” detergents for the removal of graffiti coatings resistant to removal are water‐in‐oil nanoemulsions that have been stabilized with nonionic saccharide surfactants. Nanodetergents with safe, ecofriendly ingredients were produced using high‐pressure homogenization (HPH). These ingredients included D‐limonene or 3‐methoxy‐3‐methyl‐1‐butanol, esterified vegetable oils, and alkyl polyglucosides (APG). Responsive surface methodology (RSM) optimization was used to identify the most efficient detergents for removing stubborn graffiti coatings. Two different types of black paint containing nitrocellulose or bitumen as components to strengthen the paint properties were used to create a stubborn graffiti coating on a marble surface. The effectiveness of the nanodetergents in removing the stubborn graffiti coatings was evaluated, and the results revealed a considerable variation in the pace at which the coatings could be removed by the nanodetergents, despite the fact that both paints strengthened with different additives showed similar surface properties. It was found that alkyl polyglucosides are highly efficient in stabilizing water‐in‐oil nanoemulsion systems, including diverse solvent types. These nanoemulsions can be used as specialized “brush‐on, wipe‐off” detergents for the precise removal of different graffiti coatings, which require a specified action period to prevent destroying the underlying original substrate.

Water-in-oil (w/o) nanoemulsions stabilized with amino acid surfactants (AAS) are one example of nanotechnology detergents of the “brush on, wipe off”-type for removing graffiti coatings from different sensitive surfaces. The high-pressure homogenization (HPH) process was used to obtain the nanostructured fluids (NSFs), including the non-toxic and eco-friendly components such as AAS, esterified vegetable oils, and ethyl lactate. The most effective NSF detergent was determined by response surface methodology (RSM) optimization. Afterwards, several surface properties, i.e., topography, wettability, surface free energy, and the work of water adhesion to surfaces before and after their coverage with the black graffiti paint, as well as after the removal of the paint layers by the eco-remover, were determined. It was found that the removal of graffiti with the use of the NSF detergent is more dependent on the energetic properties and microporous structure of the paint coatings than on the properties of the substrates on which the layers were deposited. The use of NSFs and knowledge of the surface properties could enable the development of versatile detergents that would remove unwanted contamination from various surfaces easily and in a controlled way.

The apparent surface free energy is one of the most important quantities in determining the surface properties of solids. So far, no method of measuring this energy has been found. The essence of contact angle measurements is problematic. Contact angles should be measured as proposed by Young, i.e., in equilibrium with the liquid vapors. This type of measurement is not possible because within a short time, the droplet in the closed chamber reaches equilibrium not only with vapors but also with the liquid film adsorbed on the tested surface. In this study, the surface free energy was determined for the plasma-activated polyoxymethylene (POM) polymer. Activation of the polymer with plasma leads to an increase in the value of the total apparent surface free energy. When using the energy calculations from the hysteresis based approach (CAH), it should be noted that the energy changes significantly when it is calculated from the contact angles of a polar liquid, whereas being calculated from the angles of a non-polar liquid, the surface activation with plasma changes its value slightly.

The contact angle is one of the most sensitive experimental values describing a junction between three phases, being influenced by the composition and properties of contacting media as well as the structure and composition of interfaces involved. The origins and importance of the contact angle in analysis of three-phase systems date back to the famous works on cohesion and adhesion of fluids published by Thomas Young in 1805 and later by Athanase Dupré in 1869. Since then, the contact angle has remained one of the most important values measured experimentally during characterization of solids and their wetting characteristics. Such measurements, however, involve solid surfaces that deviate from the idealized ones used in thermodynamic and mechanical modeling of three-phase junctions by Young, Dupré and others, and there is typically more than one value of contact angle measured on such surfaces. As a result, the attention of scientists and researchers in the past two centuries has been on development of methods for accurate contact angle measurements, interpretation of experimental values and understanding of the causes of contact angle value variation and contact angle hysteresis. This paper reviews advancements made in interpretation of experimental contact angles and their use in characterization of solid surfaces.