Of these, surfaces that combine a low surface energy … An experimental setup for measurements of impinging droplets has been created and eval-uated. equivalence point. Solubilization capacity has been quantified in terms of the molar solubilization ratio, the micelle-water partition coefficient, the first stepwise association constant between solubilizate monomer and vacant micelle, and the average number of solubilizate molecules per micelle, determined employing spectrophoto-, tensio-, and flourimetric techniques. Molecules of biological importance and especially proteins, nucleic acids and glycopolymers, are the targets, where the principles of biomolecular recognition are of great utility. In all cases, ternary phase diagrams at 25°C show that the lamellar phase. The cmc's predicted using the MT theory agreed well with the experimental cmc's and were found to be comparable to and sometimes better than the cmc's determined using the regular solution theory (RST), even though the empirical RST utilizes experimentally measured cmc's as an input. cleaning methods and the different structured Lotus-Effect® surfaces on the cleaning efficiency. nanostructured superhydrophobic surfaces was developed that is very effective in removing
Im Rahmen dieser Arbeit wurden nano-TiO2-Partikel unter Rückfluss und durch Autoklavbehandlung hergestellt. However, it is currently becoming well established that both models explain the wetting behavior more from a qualitative or practical point of view rather than giving a quantitative description. I: Isomerically Pure Anionic Surfactants, Multiscale dissipative mechanisms and hierarchical surfaces. Additionally, the QSPR models can be used to predict the cleaning efficiency of fluorescence spectroscopy gave qualitative information about the cleaning efficiency. Finally, we predicted the critical micelle concentration (cmc) of solutions of two pH-sensitive surfactants, tetradecyldimethylamine oxide (C14DAO) and hexadecyldimethyl betaine (C16Bet), at varying solution pH and surfactant composition. IV. Durch schwarze Beschichtung aktive Aufnahme und schneller Transport der Ofenhitze zum Bratgut Energieeinsparung Verkürzung der Garzeit um bis zu 30% im Vergleich zu herkömmlicher Alufolie ... Superhydrophobe Beschichtung z.B. Superhydrophob‐superhydrophile Mikrostrukturen: Auf dem Weg zum Ein‐Genom‐Zellmikroarray ... die durch dünne superhydrophobe Barrieren voneinander getrennt werden. A patchwise adsorption model, which incorporates bilayer adsorption, lateral interactions, and two-dimensional phase transitions, is developed and shown to describe the observed isotherms below the CMC. The phase behavior and performance of ASTP extraction using cationic surfactant dodecyltrimethylammonium bromide (DTAB) and anionic surfactant alkyldiphenyloxide di-sulfonate (DPDS) to extract benzene from wastewater was investigated in batch experiments. We also review a few special case studies aimed at adopting these biomimetlc schemes to design and fabricate functional self-cleaning surfaces. The parallel determination of the average aggregation number (N) and aggregate number density (Nag) in the fragmented-phase domain shows three distinct regimes: (i) a growing regime, from θ = 0 to θ = 0.17, where the size of the surface aggregates increases at constant number density; (ii) a self-repeating regime, from θ = 0.17 to θ â¼ 0.5, where the number density increases, while the size of the aggregates remains constant; the surface aggregates in this regime are undistinguishable from the regular micelles formed by TX 100 in aqueous solution (N = 110); (iii) again a growing regime, up to a point (θ = 0.8) where the adsorbed phase can be described as an assembly of surface micelles (N = 200) in close packing. angle and roll-off angle measurements were used to characterize the technical superhydrophobic
By the solution of equations of adsorption, one can obtain directly the values of surface excess of all components (surfactant ions, counterions, and nonionic surfactants molecules), which are present in the investigated system. The interaction parameters that measure the interaction between the surfactant molecules in the mixed micelle were computed by Rubingh's approach. In addition, the influence of Responding to intermolecular interactions, fluorescent dyes can recognize the medium and determine its physical parameters, such as temperature and pressure. The resulting experimental relationships are compatible with a hydrogen-bonding adsorption mechanism on silica, but not on alumina. A superhydrophobic surface is a surface with a water contact angle close to or higher than 150°. ρ = density of the liquid droplet g = acceleration due to gravity V = volume of the liquid droplet θ a = advancing appearant contact angle θ a,0 = advancing contact angle of a smooth substrate γ = surface tension of the liquid w = tower wall angle citation, Eldorado - Ressourcen aus und für Lehre, Studium und Forschung, https://eldorado.tu-dortmund.de/bitstream/2003/29168/1/Dissertation.pdf, Update/Correction/Removal Furthermore, advancing and receding contact angles of 177° and
The observed difference in the adsorption behavior is interpreted in terms of the different hydrophilic head groups of the two amphiphiles. ionic to nonionic components were analyzed by two independent theories. typical basic cleaning formulation and the influence of the additives as a function of surfactant Non-contact, optical profilometry
In the first plateau the surface-active cations are adsorbed as individual ions on the negatively charged silica gel surface through both electrostatic attraction and specific adsorption. Such interfacial aggregates can potentially be used to pattern surfaces at nanometer-length scales. There are two types of photochemical reaction proceeding on a TiO2 surface when irradiated with ultraviolet light. Although the pH values of solutions with no added acid were modeled with only qualitative accuracy, the MT theory resulted in quantitatively accurate predictions of solution pH for mixtures containing added acid. Thema: Tropfenaufprall auf superhydrophobe, nanostrukturierte Oberflächen im elektrischen Feld Jahr: 2013 Betreuer: Prof. Dr. rer. Being incorporated into structures adsorbing gas molecules, they are able to identify the gas composition. At 1.0 M NaCl addition, about 95% of xylene, 92% of ethylbenzene, 90% of toluene, and 79% of benzene are extracted into the surfactant-rich phase within a single stage extraction and the contaminant partition ratios can be as high as 395 for xylene, 273 for ethylbenzene, 206 for toluene, and 84 for benzene, which are greater than those obtained from the conventional ASTP extraction system using nonionic surfactants. cleaning formulation were examined using several optical methods. [S. Chander, D. W. Fuerstenau and D. Stigter, in Adsorption From Solution, ed. In this article, we focus on a few key aspects of superhydrophobic wetting, namely the characterization of superhydrophobic surfaces, models for the movement of drops, transitions between the Cassie and Wenzel states, and the behavior of superhydrophobic materials under condensation. about 156.1° ± 3.7°, 177° and 156°, respectively. It was found that phase separation only occurs over a narrow range of molar ratios of DTAB:DPDS from 1.6:1 to 2.4:1. Patent, DE 10 … It is now well established that selective adsorption (i.e., involving interactions other than dispersion forces) on silica is due to hydrogen bonding of surface hydroxyl groups to adsorbate molecules. Contact angle hysteresis is discussed in terms of a balance between the vibrational energy of a drop and the heights of the energy barriers between allowed metastable states. Lamellar stability is probably limited by the increase in surfactant head group area. At the same time the maximum micellar interaction parameter was obtained by the mixtures VIII and IV (â1.85 and â1.80, respectively). most efficient in the presence of the basic cleaning formulation. The effect of droplet size on contact angle was studied by droplet evaporation and a transition criterion was developed to predict when air pockets cease to exist. III. contaminated surfaces. [PDF] ... Superhydrophobe Oberflächen mit Fluorpolymeren in hierarchischen Strukturen. respectively. The unique surface structure of the lotus leaf in combination with hydrophobic epicuticular wax
In contrast to the structural dimensions, the process parameters had only a minor impact on the contact angle. Furthermore, dynamic contact
atomic force microscopy. As second theory we used our newly developed theoretical model of adsorption of ionic-nonionic surfactant mixtures. This study compares the selective adsorption of several common organic structural groups (e.g., methoxy, nitro, aceto, and amino) on water-deactivated alumina and silica. hydrophobic oily/greasy soils at low concentrations without damaging the surface. The desorption behavior in the mixed surfactant system depends on the mixing ratio of surfactants in the mixtures. In nonionic NP-15 rich mixtures, negative hysteresis is observed for the desorption of both TTAC and NP-15. In addition, the influence of
laws of Cassie and Baxter. Detergents are complex formulations containing not only single surfactants or surfactants mixtures
A comprehensive analytical model is proposed to provide a relationship between local roughness and contact angle, which is used to develop roughness distribution and to create biomimetic superhydrophobic surfaces. than dipping methods. In this review, a brief synopsis of superhydrophobicity (i.e. Oberflächen mit Rauhigkeiten im Nanometer-Bereich und erhöhter Benetzbarkeit halten dem Vereisen merklich länger stand als typisch superhydrophobe Oberflächen mit erhöhter hierarchischer Rauhigkeit und verminderter Benetzbarkeit. However, these surfaces can be damaged by wear or fouled by oily materials. For two solid bodies in contact, for wetting liquids, wetting leads to the meniscus force, which affects friction. sample, the super- hydrophobic plastic surface showed smaller roughness and higher waviness From the corrosion results it was found that, the maximum synergistic effect was obtained by the mixtures VIII (30%C + 70%N) and IV (70%C + 30%N). Observed trends due to change in salt concentration, temperature and oil type, and due to the addition of cosurfactants, are correlated and emerge from a simple global framework. The anomalously large Ham effect observed in pyrene has been studied in various solvents at room temperature by measuring the fluorescence and absorption spectra. 8 Desinfektion von Luft, Oberflächen und Gegenständen mit UV-C-Licht Desinfektion von Gegenständen Viren können bis zu 5 Tage lang auf Oberflächen über- leben[12]. The hydrophobicity of the surfaces was systematically varied by changing the relative amounts of chemisorbed thiohexadecane (CH3(CH2)15SH) and thiohexadecanol (CH2OH(CH2)15SH) surface groups. The adsorption increases rapidly beyond a certain concentration. The combination of these two functions has opened up various novel applications of TiO2, particularly in the field of building materials. Especially Genapol® LRO (90%)
Starting with the outside of the epidermis cell, ones finds the outermost layer of a thin extracellular membrane, called cuticle. The wettability and morphology of the as-fabricated surfaces were investigated by contact angle measurement and scanning electron microscopy. concentration on the cleaning efficiency were investigated. of the superhydrophobic surfaces at low concentrations. To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Meanwhile, the increase of temperature induces the transition of precipitate to vesicles. The critical micelle concentration (CMC) values of pure surfactants and their mixtures were determined by surface tension measurements at different mixed ratios. extreme non-wettability) and its implications on marine fouling are presented. the corrosion of steel pipelines in the petroleum acid job. During the desorption process, however, Surface properties of systems that are mixtures of ionic surfactants and sugar derivatives-anionic surfactant sodium dodecyl sulfate and n-dodecyl-beta-D-maltoside (SDS/DM) and cationic surfactant dodecyltrimethylammonium bromide and n-dodecyl-beta-D-glucoside (DTABr/DG)-were investigated. aqueous solution. Roughness affects the contact angle due to the increased area of solidâliquid interface and due to the effect of sharp edges of rough surfaces. Motivated by potential applications in microfluidics and in the fabrication of self-cleaning surfaces, we finally propose some guidelines to design robust superhydrophobic surfaces. models. Super-hydrophobic and super-wetting surfaces: Analytical potential? but several different ingredients. The biggest problem of the fine surface roughness is the sensitivity to oily aggregation properties of MQAS/SDS mixtures in water were examined by ocular observations and DLS. Various roughness distributions are considered, including periodic and surfaces with rectangular, hemispherically topped cylindrical, conical and pyramidal asperities and the random Gaussian height distribution. colloidal stabilization, ore flotation, and soil removal; however, the interfacial aggregation of surfactant molecules is Es gibt zwei Herausforderungen. Further investigations were carried out to study the influence of the
Die meisten bisherigen superhydrophoben Oberflächen haben ein großes Haltbarkeitsproblem. fundamental physical mechanisms of wetting, including the transition between The formation of responsive/"smart" surfaces, which adjust their physico-chemical properties to variations in some outside physical stimulus, including light, temperature, electric field, or solvent, is also described. fluorescence spectroscopy gave qualitative information about the cleaning efficiency. accumulation of soil in this area. Equimolar cationic-cationic-nonionic ternary surfactant systems showed lower solubilization efficiency than their binary cationic-nonionic counterparts but higher than cationic-cationic ones. excellent. surfactant concentration, surfactant structure and type of contamination were investigated. The viscosity of the mixed systems of C14âsarcosinate with cationic surfactants (having higher chain length) at various mole fractions suggested a growth in mixed micelles with maxima at 0.4 mole fraction of C14âsarcosinate. In this region, only unassociated, first-layer, surfactant molecules are present on the surface and at least the terminal 10th through the 12th carbons in the alkyl chain interact strongly with the surface, in addition to the charged head-surface electrostatic attraction. These structures-surprisingly different from earlier models-appear to result from a compromise between the natural The presence of the amphiphilic molecules is effective in lowering the contact angle in a hydrophobic or still superhydrophobic range. Cationic surfactants exhibited lesser solubilization capacity than nonionics in each series of surfactants with higher efficiency in the C16 series compared to the C12 series. The adsorption of the mixtures C14E6âC10E6 and C12E5âC12E8 onto a silica surface has been studied by in situ null ellipsometry. Dies ermöglicht der Herstellung von anisometrischen „patchy particles“ durch Verwendung von zusätzlichen magnetischen Fe3O4-Nanopartikeln. Certain plant leaves are known to be superhydrophobic in nature due to their roughness and the presence of a thin wax film on the leaf surface. Characterizations by transmission electron microscopy, Fourier transformation infrared spectroscopy, and thermal gravimetric analysis were also conducted. applications), and dynamic surface tension (an important interfacial Triton Xâ100 shows a steep rise in cloud point in the presence of C14âsarcosinate. Then, at a particular concentration known as the hemimicelle concentration (h.m.c. Download Free PDF. 2 shows the basic, layered stratification. We have extended to the adsorbed phase formed by a nonionic surfactant (Tritron X 100 (TX 100)) at the solid (silica)-aqueous solution interface the fluorescence decay methods developed by others for the determination of micellar aggregation numbers. The conical micro structures were varied in diameter and height ranging from 5 to 20 μ$\upmu $ m as were the process parameters within the framework of a statistical experimental plan. Friction, superhydrophobicity, and biomimetics, Hierarchical roughness makes superhydrophobic states stable, Molecular Organization of Surfactants at Solid-Liquid Interfaces, Surfactant adsorption at superhydrophobic surfaces, From superhydrophobic to superhydrophilic surfaces tuned by surfactant solutions, Influence of Surface Hydrophobicity on the Layer Properties of Adsorbed Nonionic Surfactants, Adsorption Behavior of Two Binary Nonionic Surfactant Systems at the SilicaâWater Interface, Multiple Equilibrium Droplet Shapes and Design Criterion for Rough Hydrophobic Surfaces, Characterization of thin nonionic surfactant films at the silica/water interface by means of ellipsometry, Fluorescence decay study of the adsorption of nonionic surfactants at the solid-liquid interface. Cerman Z, Striffler BF, Barthlott W, Stegmeier T, Scherrieble A, von Arnim V (2006) Superhydrophobe Oberflächen für Unterwasseranwendungen. Verification of the model is conducted using experimental data for the contact angle of water droplet on a lotus leaf surface. Non-adhesive and water-repellent surfaces are required for many tribological applications. The superhydrophobicity is recoverable simply by water rinsing. The effect of relative humidity is also investigated to study the environmental effects on adhesion and friction. We also compared predictions to data from the literature for mixtures of C12DAO and SDS. Diese nano-TiO2-Partikel bestehen aus agglomeratfreien Anatas. Their use as water-repellent coatings is established, but their potential for use in microfluidics and sensor applications remains largely unfulfilled. Superhydrophobe Oberflächen mit mikro- und nanohierarchischer Rauheit weisen eine exzellente Wasserabweisung und eine tiefe Adhäsion zu Wasser auf. efficiency. We first compared the predicted micellar titration data to experimental micellar titration data that we obtained for varying compositions of mixed micelles containing the pH-sensitive surfactant dodecyldimethylamine oxide (C12DAO) mixed with either a cationic surfactant (dodecyltrimethylammonium bromide, C12TAB), a nonionic surfactant (dodecyl octa(ethylene oxide), C12E8), or an anionic surfactant (sodium dodecyl sulfate, SDS) surfactant. and stiction. surfactant), superspreading (or superwetting) by aqueous surfactant Our results reveal that it is possible to produce robust superhydrophobic surfaces in a single-step liquid silicone injection molding process. A simple semi-quantitative model is proposed to account for the observed relation between the surface topography and the robustness of fakir non-wetting states. Das Verhalten von solchen texturierten superhydrophoben In the case of pyrene as a standard contamination, video-enhanced contrast microscopy and WO2018065094A1 PCT/EP2017/001171 EP2017001171W WO2018065094A1 WO 2018065094 A1 WO2018065094 A1 WO 2018065094A1 EP 2017001171 W EP2017001171 W EP 2017001171W WO 2018065094 A1 WO2018065094 A1 WO 2018065094A1 Authority WO WIPO (PCT) Prior art keywords polymer foam composition highly fluorinated monomer super Prior art date 2016-10-06 Application … The stability of the lamellar phase is a function of the periodic repeat distances and surfactant head group areas as measured by small angle X-ray scattering, and the results are discussed in terms of the inter- and intra-bilayer interactions. The desorption behavior of cationicânonionic surfactant mixtures, tetradecyltrimethylammonium chloride (TTAC) and pentadecylethoxylated nonyl phenol (NP-15), at the aluminaâwater interface was studied. Furthermore, dynamic contact Photocatalysis has recently become a common word and various products using photocatalytic functions have been commercialized. 172° were measured. not yet well understood. Dies führt dazu, dass sich unterhalb des Tropfens eine stabile Luftschicht bildet (Abb. Both Lotus-Effect® surfaces showed significant differences in their
Superhydrophobic functional surfaces have numerous applications. free curvature as defined by intermolecular interactions and the constraints imposed by specific surfactant-surface interactions. Increase in hydrophobicity of head groups of cationics by incorporation of ethyl or benzyl groups enhanced their solubilization capacity. An increase in the hydrophileâlipophile balance of the nonionic surfactant also reduced the ÎH10 and ÎS10 values for complex formation; the formation of the dyeâcationic surfactant complexes in ternary mixtures is an entropy-driven process, regardless of nonionic surfactant structure. efficiency. Dotierungen des TiO2 sind durch Autolavbehandlung mit unterschiedlichen Dotiermitteln und Dotiermittelmengen durchgeführt worden. surface roughness upon wetting and capillary adhesion force is discussed. surfactants. Die Forscher aus Bonn, Rostock und Karlsruhe haben nun enträt- As expected, Henry's Law describes the adsorption at sufficiently low surfactant concentrations. angle measurements have been performed to study the wetting of Lotus-Effect® surfaces after the
The dynamic contact angle measurements revealed that the glass surface was Woran liegt das? This in turn is proposed to cause the desorption of NP-15 significant. Here, we review the progress of the scientific research on TiO2 photocatalysis as well as its industrial applications, and describe future prospects of this field mainly based on the present authors' work. Notably, research on superhydrophobic surfaces has not only fundamental interest but various possible functional applications in micro- and nano-materials and devices. and Hostapur® OS (83%) have been demonstrated to be very effective in removing the standard soil The effect of micropatterning and nanopatterning on the hydrophobicity was investigated for two different polymers with micropatterns and nanopatterns. grayscale evaluations. Introduction. The cleaning efficiency of 15 commercial surfactants of different surfactant nature and one basic
TEGOTENS® AM VSF proved to be unsuitable for cleaning micro-und nanostructured Lotus- Effect® the Open University This was confirmed by fluorescence polarization measurement. In general the superhydrophobic plastic surface was easier to clean than the
lotus leaf. Fluorescence sensors are also applicable in solutions, being efficient in the broadest possible range of target concentrations. The MT theory presented here represents the first molecular-based quantitative description of the micellization behavior of mixtures of pH-sensitive surfactants and conventional surfactants, and allows qualitative and quantitative predictions of the micellization behavior of a variety of surfactant systems. nanostructured superhydrophobic surfaces was developed that is very effective in removing recommendations for the design of superhydrophobic surfaces are formulated. solution for superhydrophobic surfaces that already function at low concentrations specifically in
into the nanotextures, lead to an irreversible loss of the self- cleaning properties and an
This finding is in contrast to that obtained for the interactions between cationic and nonionic surfactants under the same conditions. biomimetic superhydrophobic surfaces have been fabricated by mimicking the structure of the and Jisc. For ionic surfactants, electrostatic interactions between the lamellae and intra-aggregate interactions are important. surfactants on Lotus-Effect® surfaces. Among many candidates for photocatalysts, TiO2 is almost the only material suitable for industrial use at present and also probably in the future. When a liquid drop impinges a hydrophobic rough surface it can either bounce off the surface (fakir droplets) or be impaled and strongly stuck on it (Wenzel droplets). The best cleaning efficiency has been measured for Genapol® LRO (alkyl diglycol ether
(c) 2006, Elsevier B.V. All rights reserved. The variation of these group adsorption energies with intramolecular electronic and steric effects was also studied. The approach for determination of the number of surfactant ions in a hemimicelle from the adsorption isotherms proposed by Chander et al. Studies on silicon surfaces patterned with pillars of varying diameter, height and pitch values and deposited with a hydrophobic coating were performed to demonstrate how the contact angles vary with the pitch. The importance of hierarchical roughness structure on destabilization of air pockets is discussed. Der Begriff hydrophob stammt aus dem Altgriechischen (ὕδωρ hýdor „Wasser“ sowie φόβος phóbos „Furcht“) und bedeutet wörtlich „wassermeidend“. The best cleaning efficiency has been measured for Genapol® LRO (alkyl diglycol ether For glass we obtained 1.527 µm, 2.195 µm and 26.918 µm, respectively. hydrophobic oily/greasy soils at low concentrations without damaging the surface. Material und Methode. In general, the cleanability of the anionic surfactants proved to be The structure of adsorbed octa(oxyethlyene) n-dodecyl ether (C12E8) layers at a series of goldâalkanethiolate surfaces was investigated by atomic force microscopy. Scanning electron microscopy, contact Acid Red 88 and C.I. The biggest problem of the fine surface roughness is the sensitivity to oily
The enthalpy/entropy balance of the formation of the adsorption layer has been described in terms of thermodynamic potential functions. silica. We obtained a good agreement with experimental data using the same set of model parameters for a whole range of studied compositions of a given surfactant mixture. organic contaminants will solubilize into the surfactant aggregates and concentrate in the small volume surfactant-rich phase. To effectively resist these scale-dependent mechanisms, a multiscale (hierarchical) roughness is required. This leads to the establishment of a design criterion for a robust hydrophobic rough surface on which the apparent contact angle will not change as a result of an external disturbance. The, The mixing properties of Gemini surfactants are significantly important to the large-scale application of these surfactants. Barthlott W& Ehler N Rasterelektronenmikroskopie der Epidermis-Oberflächen von Spermatophyten. When cationic and anionic surfactants are mixed at certain surfactant concentrations and compositions, the solution separates into two immiscible aqueous phases. order to investigate the effect of surfactant structure on the cleaning efficiency by using In this contribution, we briefly discuss how various physicochemical properties of surfaces affect the wettability and self-cleaning character of both naturally occurring and synthetic surfaces. Antifingerprint- Oberflächen. At a total surfactant concentration of 50mM, the benzene partition ratio is 48 and 72% of the benzene is extracted into the surfactant-rich phase solution in a single stage extraction, which is superior performance compared to ASTP extraction using nonionic surfactants. The present thesis is part of the BMBF project “Biomimetische superhydrophobe Oberflächen: Funktionserhaltung durch … Comparisons with adsorption on silica, Contact Angle Hysteresis. Here the wetting of ionic and nonionic surfactant solutions on a superhydrophobic interface, obtained by using a mixed inorganic-organic coating providing a fractal-like structure, has been investigated to define the role of adsorption at these interfaces. a contact angle of 167.7° ± 1.5°. Interactions between surfactant solutions and solid surfaces play a key role in technologically important processes such as Silicone surfaces, which aim to imitate the surface of the lotus plant, were prepared using a microstructured injection mold. Therefore, each of the eleven surfactants were combined with a Standard free energies of adsorption from pentane solution were measured for each group on both alumina and silica, within the linear isotherm region.