Added-Value Surfactants

Antimicrobial Properties of Monomeric and Dimeric Catanionic Surfactant System

Cationic gemini surfactants are used due to their broad spectrum of activity, especially surface, anticorrosive and antimicrobial properties. Mixtures of cationic and anionic surfactants are also increasingly described. In order to investigate the effect of anionic additive on antimicrobial activity, experimental studies were carried out to obtain MIC (minimal inhibitory concentration) against E. coli and S. aureus bacteria. Two gemini surfactants (12-6-12 and 12-O-12) and two single quaternary ammonium salts (DTAB and DDAC) were analyzed. The most commonly used commercial compounds of this class, i.e., SDS and SL, were used as anionic additives. In addition, computer quantum mechanical studies were also carried out to confirm the relationship between the structure of the mixture and the activity. The obtained results of microbiological tests and quantum mechanical calculations are in agreement with each other and show the lack of synergism in catanionic mixtures in the case of antibacterial activity.

Photoswitchable Arylazopyrazole Surfactants at the Water-Air Interface: A Microscopic Perspective

Surfactants play an important role in modifying the properties of water-air interfaces. Here, we combine information from molecular dynamics simulations, surface tensiometry, and vibrational sum-frequency generation spectroscopy to study the interfacial behavior of photoswitchable arylazopyrazole (AAP) surfactants. This combination of the experimental techniques allows a direct relation between surface tension and surface concentration rather than just the bulk concentration. Specifically, we conducted a comparison between two derivatives, one with an octyl terminal group (O-AAP) and the other without this group (H-AAP), focusing on their respective E and Z isomers. From the simulations of these four systems, we see that those with a stronger cluster formation, likely resulting from higher intermolecular attractive interactions, display higher surface tensions for the intermediate surface excess. In some cases, even a small but noticeable maximum in the surface tension isotherm is observed for systems with strong cluster formation. Such a maximum is not observed in the experiments, although such an observation would be compatible with the general properties of the Frumkin isotherm. We exclude that the peak is due to the finite width of the simulation box. Apart from this effect, the general features of the surface tension are consistent between the experiment and simulation. Evidence is also provided that it is primarily the interaction of the aromatic rings that determines the strength of the surfactant interactions.

Visible Light-Induced Photocatalyst-Free Diastereoselective Iodosulfonylation of Cyclopropenes in Water

This study presents a greener approach to the visible-light-induced micellar-catalyzed diastereoselective iodosulfonylation of cyclopropenes in a water medium. Remarkably, this process operates without a photocatalyst. Instead, it utilizes an electron-donor-acceptor complex formed between sulfonyl chloride and sodium iodide. This method is highly efficient and broadly applicable for both aromatic and aliphatic sulfonyl chlorides. Furthermore, this protocol enables the transformation of iodosulfonated cyclopropanes into sulfonated cyclopropenes, highlighting its substantial value as a versatile and powerful tool in synthetic chemistry.

Multiheaded Cationic Surfactants with Dedicated Functionalities: Design, Synthetic Strategies, Self-Assembly and Performance

Contemporary research concerning surfactant science and technology comprises a variety of requirements relating to the design of surfactant structures with widely varying architectures to achieve physicochemical properties and dedicated functionality. Such approaches are necessary to make them applicable to modern technologies, such as nanostructure engineering, surface structurization or fine chemicals, e.g., magnetic surfactants, biocidal agents, capping and stabilizing reagents or reactive agents at interfaces. Even slight modifications of a surfactant's molecular structure with respect to the conventional single-head-single-tail design allow for various custom-designed products. Among them, multicharge structures are the most intriguing. Their preparation requires specific synthetic routes that enable both main amphiphilic compound synthesis using appropriate step-by-step reaction strategies or coupling approaches as well as further derivatization toward specific features such as magnetic properties. Some of the most challenging aspects of multicharge cationic surfactants relate to their use at different interfaces for stable nanostructures formation, applying capping effects or complexation with polyelectrolytes. Multiheaded cationic surfactants exhibit strong antimicrobial and antiviral activity, allowing them to be implemented in various biomedical fields, especially biofilm prevention and eradication. Therefore, recent advances in synthetic strategies for multiheaded cationic surfactants, their self-aggregation and performance are scrutinized in this up-to-date review, emphasizing their applications in different fields such as building blocks in nanostructure engineering and their use as fine chemicals.

Surfactant Semiconductors as Trojan Horses in Cell-Membranes for On-Demand and Spatial Regulation of Oxidative Stress

Oxidative stress is a cause for numerous diseases and aging processes. Thus, researchers are keen to tune the level of intracellular stress and to learn from that. An unusual approach is presented here. The methodology involves multifunctional surfactants. Although their molecular design is nonbiological-a fullerenol head group attached covalently to pi-conjugated dyes-the surfactants possess superior biocompatibility. Using an intrinsic fluorescence signal as a probe, it is shown that the amphiphiles become incorporated into the Caco-2 cells. There, they are able to exhibit additional functions. The compound reduces cellular stress in dark reaction pathways. The antagonistic property is activated under irradiation, the photocatalytic production of reactive oxygen species (ROS), resulting in cell damage. The feature is activated even by near-infrared light (NIR-light) via a two-photon process. The properties as molecular semiconductors lead to a trojan horse situation and allows the programming of the spatial distribution of cytotoxicity.

Fabrication of Encapsulated Gemini Surfactants

(1) Background: Encapsulation of surfactants is an innovative approach that allows not only protection of the active substance, but also its controlled and gradual release. This is primarily used to protect metallic surfaces against corrosion or to create biologically active surfaces. Gemini surfactants are known for their excellent anticorrosion, antimicrobial and surface properties; (2) Methods: In this study, we present an efficient methods of preparation of encapsulated gemini surfactants in form of alginate and gelatin capsules; (3) Results: The analysis of infrared spectra and images of the scanning electron microscope confirm the effectiveness of encapsulation; (4) Conclusions: Gemini surfactants in encapsulated form are promising candidates for corrosion inhibitors and antimicrobials with the possibility of protecting the active substance against environmental factors and the possibility of controlled outflow.

An overview on surfactants as pollutants of concern: Occurrence, impacts and persulfate-based remediation technologies

Surfactants are molecules that reduce interfacial energy and increase solubility of other pollutants in water. These properties make them suitable for various domestic and industrial applications, soil remediation, pesticide formulation, among others. The increase in their use and the lack of strict regulations regarding their disposal and management is a matter of concern and requires more attention since the release and distribution of these compounds into the environment can modify important water quality parameters. As a result of these changes, different toxicological effects to aquatic organisms are discussed and exposed herein. On this basis, we provide an overview of the classes of surfactants, as well as their occurrence in different aqueous matrices. In addition, existing regulations around the world regarding their concentration limit for different environments are discussed. Current research focuses on the application of conventional treatments, such as biological treatments; notwithstanding, more toxic and bioaccumulative products can be generated. Advanced Oxidation Processes are promising alternatives and have also been widely applied for the removal of surfactants. This study provides, for the first time, an overview of the application of persulfate-based processes for surfactants degradation based on recent literature findings, as well as the various factors related to the activation of the persulfate anions. This review also highlights the challenges and opportunities for future research to overcome the obstacles to the practical application of this process.

Halloysite nanotubes as nanoreactors for heterogeneous micellar catalysis

HYPOTHESIS

Electrostatic attractions between the anionic head group of sodium alkylsulphates and the positively charged inner surface of halloysite nanotubes (HNTs) drive to the formation of tubular inorganic micelles, which might be employed as nanoreactors for the confinement of non polar compounds in aqueous media. On this basis, sodium alkylsulphates/halloysite hybrids could be efficient nanocatalysts for organic reactions occurring in water.

EXPERIMENTS

Sodium decylsulphate (NaDeS) and sodium dodecylsulphate (NaDS) were selected for the functionalization of the halloysite cavity. The composition, the structure and the surface charge properties of the hybrid nanotubes were determined. The actual formation of inorganic micelles was explored by studying the microviscosity and polarity characteristics of the surfactant modified nanotubes through fluorescence spectroscopy experiments using DiPyme as probe. The performances of the sodium alkylsulphates/halloysite composites as micellar catalysts for the Belousov-Zhabotinsky (BZ) reaction were investigated.

FINDINGS

The halloysite functionalization with sodium alkylsulphates generated the formation of hydrophobic microdomains with an enhanced microviscosity. Compared to the surfactant conventional micelles, the functionalized nanotubes induced larger enhancements on the rate constant of the BZ reaction. This is the first report on the surfactant/halloysite hybrids showing their efficiencies as reusable nanocatalysts, which are dependent on their peculiar microviscosity and polarity properties.

Cationic gemini surfactant properties, its potential as a promising bioapplication candidate, and strategies for improving its biocompatibility: A review

Gemini surfactants consist of two cationic monomers of a surfactant linked together with a spacer. The specific structure of a cationic gemini surfactant is the reason for both its high surface activity and its ability to decrease the surface tension of water. The high surface activity and unique structure of gemini surfactants result in outstanding properties, including antibacterial and antifungal activity, anticorrosion properties, unique aggregation behaviour, the ability to form various structures reversibly in response to environmental conditions, and interactions with biomacromolecules such as DNA and proteins. These properties can be tailored by selecting the optimal structure of a gemini surfactant in terms of the nature and length of its alkyl substituents, spacer, and head group. Additionally, regarding their properties, comparison with their monomeric counterparts demonstrates that gemini surfactants have higher performance efficacy at lower concentrations. Hence, less material is needed, and the toxicity is lower. However, there are some limitations regarding their biocompatibility that have led researchers to develop amino acid-based and sugar-based gemini surfactants. Owing to their remarkable properties, cationic gemini surfactants are promising candidates for bioapplications such as drug delivery systems, gene carriers, and biomaterial surface modification.

Biological properties and conformational studies of amphiphilic Pd(II) and Ni(II) complexes bearing functionalized aroylaminocarbo-N-thioylpyrrolinate units

A series of novel palladium(II) and nickel(II) complexes of multifunctionalized aroylaminocarbo-N-thioylpyrrolinates were synthesized and characterized by analytical and spectroscopic techniques. The biological properties of the freshly prepared compounds were screened against S. aureus, B. subtilis, A. hydrophila, E. coli, and A. baumannii bacteria and antituberculosis activity against M. tuberculosis H37Rv strains. Also, the antifungal activity was studied against C. albicans, C. tropicalis, and C. glabrata standard strains. A deep conformational survey was monitored using DFT calculations with the aim to explain the importance of the final conformation in the biological experimental results.

3,4-Ethylenedioxythiophene (EDOT) End-Group Functionalized Poly-ε-caprolactone (PCL): Self-Assembly in Organic Solvents and Its Coincidentally Observed Peculiar Behavior in Thin Film and Protonated Media

End-group functionalization of homopolymers is a valuable way to produce high-fidelity nanostructured and functional soft materials when the structures obtained have the capacity for self-assembly (SA) encoded in their structural details. Herein, an end-functionalized PCL with a π-conjugated EDOT moiety, (EDOT-PCL), designed exclusively from hydrophobic domains, as a functional "hydrophobic amphiphile", was synthesized in the bulk ROP of ε-caprolactone. The experimental results obtained by spectroscopic methods, including NMR, UV-vis, and fluorescence, using DLS and by AFM, confirm that in solvents with extremely different polarities (chloroform and acetonitrile), EDOT-PCL presents an interaction- and structure-based bias, which is strong and selective enough to exert control over supramolecular packing, both in dispersions and in the film state. This leads to the diversity of SA structures, including spheroidal, straight, and helical rods, as well as orthorhombic single crystals, with solvent-dependent shapes and sizes, confirming that EDOT-PCL behaves as a "block-molecule". According to the results from AFM imaging, an unexpected transformation of micelle-type nanostructures into single 2D lamellar crystals, through breakout crystallization, took place by simple acetonitrile evaporation during the formation of the film on the mica support at room temperature. Moreover, EDOT-PCL's propensity for spontaneous oxidant-free oligomerization in acidic media was proposed as a presumptive answer for the unexpected appearance of blue color during its dissolution in CDCl3 at a high concentration. FT-IR, UV-vis, and fluorescence techniques were used to support this claim. Besides being intriguing and unforeseen, the experimental findings concerning EDOT-PCL have raised new and interesting questions that deserve to be addressed in future research.

Self-Assembly of Photoresponsive Molecular Amphiphiles in Aqueous Media

Amphiphilic molecules, comprising hydrophobic and hydrophilic moieties and the intrinsic propensity to self-assemble in aqueous environment, sustain a fascinating spectrum of structures and functions ranging from biological membranes to ordinary soap. Facing the challenge to design responsive, adaptive, and out-of-equilibrium systems in water, the incorporation of photoresponsive motifs in amphiphilic molecular structures offers ample opportunity to design supramolecular systems that enables functional responses in water in a non-invasive way using light. Here, we discuss the design of photoresponsive molecular amphiphiles, their self-assembled structures in aqueous media and at air-water interfaces, and various approaches to arrive at adaptive and dynamic functions in isotropic and anisotropic systems, including motion at the air-water interface, foam formation, reversible nanoscale assembly, and artificial muscle function. Controlling the delicate interplay of structural design, self-assembling conditions and external stimuli, these responsive amphiphiles open several avenues towards application such as soft adaptive materials, controlled delivery or soft actuators, bridging a gap between artificial and natural dynamic systems.

Voltammetry as a Tool to Monitor the Aggregation Behavior of a Zwitterionic Ferrocene Surfactant

Amphiphiles are unique in their ability to self-assemble in aqueous solution into aggregates. The control of the self-organization of amphiphiles and the live monitoring of the ensuing structure changes by analytical methods are key challenges in this field. One way to gain control and to trigger the self-assembly/disassembly of amphiphiles is to introduce a redox-active constituent to the amphiphile structure, as is the case with metallosurfactants. In this work, we report a cyclic and square-wave voltammetric study on the multi-stimuli-responsive amphiphile 1-(Z)-heptenyl-1'-dimethylammoniummethyl-(3-sulfopropyl)ferrocene (1). We observe separate waves/peaks for molecules of 1 present as the monomer in its electrode-immobilized, its freely diffusing form, and its aggregated form. This allows for a direct monitoring of how the underlying equilibria depend on the concentration and time. Isothermal titration calorimetry indicates that aggregation is entropically and enthalpically favored. Our findings thus illustrate the utility of voltammetric methods for investigating self-assembly processes of redox-active amphiphiles and their redox switchability.

Molecular fusion of surfactant and Lewis-acid properties for attacking dirt by catalytic bond cleavage

The capability of ordinary surfactants in solubilizing hydrophobic compounds can come to a limit, if the extension of a contaminant is too large. An attractive goal is the development of surfactants which can actively reduce the size of dirt. Because strong Lewis acids are known to catalyze both bond formation and cleavage, an integration into the surfactant's molecular framework is tempting. End-group functionalized hepta-dentate ligands, which coordinate to metal ions preventing deactivation by hydrolysis over a broad range of pH values while maintaining strong Lewis-acidity, are herein presented. After proof of amphiphilicity and surfactant characteristics, catalytic properties are investigated for different reactions including the cleavage of proteins. The compounds perform better than benchmark catalysts concerning the attack of unreactive amide bonds. A study with two Sc³⁺ species as the active site, one non-amphiphilic, the other one being surface-active, underlines the positive effect of surfactant properties for boosting catalytic efficiency.

Visualization and characterization of metallo-aggregates using multi-photon microscopy

A simple and cost-effective method based on multi-photon microscopy is presented for the preliminary screening of the general morphology, size range and heterogeneity of Ir(iii) nano-aggregate formulations.

Multi-photon microscopy can be an excellent complementary technique for the characterization of nano-aggregates containing metallic photosensitizers with multi-photon emission properties.

Recent advances on micellar catalysis in water

Water is the universal solvent in nature to catalyze the biological transformation processes. However, owing to the immiscibility of many reagents in water, synthesis chemistry relies heavily on organic solvent. Micellar media is a green alternative to traditional petroleum feedstock derived solvents, which is recently attracting increasing research attention. The present review deals with the recent advances in micellar catalysis with an emphasis on the new "tailor-made" surfactants for various reactions. A brief overview of commercial surfactants, including anionic micelles, cationic micelles, and nonionic micelles is presented. More importantly, an attempt was made to discuss systematically the recent research progress on new surfactants by introducing structures, micellar effects and recycling process, aiming to serve as the basis for future development of surfactants.

Foray into Concepts of Design and Evaluation of Microemulsions as a Modern Approach for Topical Applications in Acne Pathology

With a fascinating complexity, governed by multiple physiological processes, the skin is considered a mantle with protective functions which during lifetime are frequently impaired, triggering dermatologic disorders. As one of the most prevalent dermatologic conditions worldwide, characterized by a complex pathogenesis and a high recurrence, acne can affect the patient's quality of life. Smart topical vehicles represent a good option in the treatment of a versatile skin condition. By surpassing the stratum corneum known for diffusional resistance, a superior topical bioavailability can be obtained at the affected place. In this direction, the literature study presents microemulsions as a part of a condensed group of modern formulations. Microemulsions are appreciated for their superior profile in matters of drug delivery, especially for challenging substances with hydrophilic or lipophilic structures. Formulated as transparent and thermodynamically stable systems, using simplified methods of preparation, microemulsions have a simple and clear appearance. Their unique structures can be explained as a function of the formulation parameters which were found to be the mainstay of a targeted therapy.

Ferro-self-assembly: magnetic and electrochemical adaptation of a multiresponsive zwitterionic metalloamphiphile showing a shape-hysteresis effect

Metallosurfactants are molecular compounds which combine the unique features of amphiphiles, like their capability of self-organization, with the peculiar properties of metal complexes like magnetism and a rich redox chemistry. Considering the high relevance of surfactants in industry and science, amphiphiles that change their properties on applying an external trigger are highly desirable. A special feature of the surfactant reported here, 1-(Z)-heptenyl-1′-dimethylammonium-methyl-(3-sulfopropyl)ferrocene (6), is that the redox-active ferrocene constituent is in a gemini-position. Oxidation to 6⁺ induces a drastic change of the surfactant's properties accompanied by the emergence of paramagnetism. The effects of an external magnetic field on vesicles formed by 6⁺ and the associated dynamics were monitored in situ using a custom-made optical birefringence and dual dynamic light scattering setup. This allowed us to observe the optical anisotropy as well as the anisotropy of the diffusion coefficient and revealed the field-induced formation of oriented string-of-pearls-like aggregates and their delayed disappearance after the field is switched off.

The self-organization properties of a stimuli responsive amphiphile can be altered by subjecting the paramagnetic oxidized form to a magnetic field of 0.8 T and monitored in real time by coupling optical birefringence with dynamic light scattering.

Effects of Biosurfactants on Enzymatic Saccharification and Fermentation of Pretreated Softwood

The enzymatic hydrolysis of cellulose is inhibited by non-productive adsorption of cellulases to lignin, and that is particularly problematic with lignin-rich materials such as softwood. Although conventional surfactants alleviate non-productive adsorption, using biosurfactants in softwood hydrolysis has not been reported. In this study, the effects of four biosurfactants, namely horse-chestnut escin, Pseudomonas aeruginosa rhamnolipid, and saponins from red and white quinoa varieties, on the enzymatic saccharification of steam-pretreated spruce were investigated. The used biosurfactants improved hydrolysis, and the best-performing one was escin, which led to cellulose conversions above 90%, decreased by around two-thirds lignin inhibition of Avicel hydrolysis, and improved hydrolysis of pretreated spruce by 24%. Red quinoa saponins (RQS) addition resulted in cellulose conversions above 80%, which was around 16% higher than without biosurfactants, and it was more effective than adding rhamnolipid or white quinoa saponins. Cellulose conversion improved with the increase in RQS addition up to 6 g/100 g biomass, but no significant changes were observed above that dosage. Although saponins are known to inhibit yeast growth, no inhibition of Saccharomyces cerevisiae fermentation of hydrolysates produced with RQS addition was detected. This study shows the potential of biosurfactants for enhancing the enzymatic hydrolysis of steam-pretreated softwood.

Recent designer surfactants for catalysis in water

Recent development of new designer surfactants further spurs the development of micellar catalysis in water for chemical transformations and catalysis, providing reliable alternatives to the employment of organic solvents.

NHC-Metallosurfactants as Active Polymerization Catalysts

Next-generation surfactants provide extended functionality apart from their amphiphilic properties. We present two novel metallosurfactants characterized by an N-heterocyclic carbene (NHC) head bearing Cu(I) and Fe(II). An innovative approach for their application in emulsion polymerizations under atom transfer radical polymerization (ATRP) conditions was developed. Thereby the complexes fulfilled the role of emulsifiers, active catalysts, and stabilization agents at once. Polymerization of methyl methacrylate (MMA) yielded stable poly(methyl methacrylate) (PMMA) colloids in water with the catalyst located at the surface of the colloids. The termination of PMMA with a bromine moiety enabled the subsequent copolymerization with styrene via macroinitiation and PMMA-polystyrene (PS) core-shell particles were obtained. Gel permeation chromatography (GPC) and selective gradient NMR experiments revealed a covalent linkage between the PMMA core and the PS shell.

Reorganization from Kinetically Stable Aggregation States to Thermodynamically Stable Nanotubes of BINOL-Derived Amphiphiles in Water

The synthesis and self-assembly behavior of newly designed BINOL-based amphiphiles is presented. With minor structural modifications, the aggregation of these amphiphiles could be successfully tuned to form different types of assemblies in water, ranging from vesicles to cubic structures. Simple sonication induced the rearrangement of different kinetically stable aggregates into thermodynamically stable self-assembled nanotubes, as observed by cryo-TEM.

Magnetic Gemini Surfactants

A homologous series of Gemini surfactants, dimethylene-1,2-bis(alkyldimethyl-ammonium bromide) (referred to as n-2-n·2Br, n = 14, 16, and 18) and Fe- or lanthanide metal-based magnetic Gemini surfactants (abbreviated as n-2-n·2X, X = Fe, Ce, and Gd), were first synthesized. Measurements of surface tension and electrical conductivity determine the physical quantities related to the surface activities of n-2-n·2Br and n-2-n·2X, and the magnetic behaviors of n-2-n·2X are elucidated by superconducting quantum interference device magnetometry. Thermogravimetric analysis and differential scanning calorimetry have been used to investigate thermotropic liquid crystalline properties of all aforementioned surfactants, and the liquid crystal textures were further observed via polarizing optical microscopy. These results reveal that for magneto-responsive Gemini surfactants, both magnetic counterions and alkyl chain lengths have certain effect on surface activities, magnetism, and thermotropic phase behavior. We summed up these changes and discussed the causes, which could provide a new insight into controlling the properties of magnetic surfactants.

Surfactant-Type Catalyst for Aerobic Oxidative Coupling of Hydrazine with Thiol in Water

A series of PEG-functionalized nitrogen ligands were developed to conduct an aerobic oxidative cross-coupling reaction between alkyl- or aryl-hydrazines with thiols in water. This surfactant-type catalyst enables high efficiencies and selectivities, while tolerating a large variety of functional groups. The mother liquor is still catalytically active after five runs.

Light-Triggered Boost of Activity of Catalytic Bola-Type Surfactants by a Plasmonic Metal-Support Interaction Effect

The maximization of activity is a general aim in catalysis research. The possibility for light-triggered enhancement of a catalytic process, even if the process is not photochemical in nature, represents an intriguing concept. Here, we present a novel system for the exploration of the latter idea. A surfactant with a catalytically active head group, a protonated polyoxometalate (POM) cluster, is attached to the surface of a gold nanoparticle (Au NP) using thiol coupling chemistry. The distance of the catalytically active center to the gold surface could be adjusted precisely using surfactants containing hydrocarbon chains (C n) of different lengths ( n = 4-10). Radiation with VIS-light has no effect on the catalytic activity of micellar aggregates of the surfactant. The situation changes, as soon as the surfactants have been attached to the Au NPs. The catalytic activity could almost be doubled. It was proven that the effect is caused by coupling the surface plasmon resonance of the Au NPs with the properties of the POM head group. The improvement of activity could only be observed if the excitation wavelength matches the absorption band of the used Au NPs. Furthermore, the shorter the distance between the POM group and the surface of the NP, the stronger is the effect. This phenomenon was explained by lowering the activation energy of the transition state relevant to the catalytic process by the strong electric fields in the vicinity of the surfaces of plasmonic nanoparticles. Because the catalytic enhancement is wavelength-selective, one can imagine the creation of complex systems in the future, a system of differently sized NPs, each responsible for a different catalytic step and activated by light of different colors.

Photocontrolled self-assembly of azobenzene nanocontainers in water: light-triggered uptake and release of lipophilic molecules

A simple azobenzene based photo-surfactant thanks to unique photo-triggerable spontaneous emulsification characteristics, allows a clean, reversible and fatigue resistant uptake and release of small molecules in aqueous solution.

Added-Value Surfactants

Surfactants are ubiquitous in cellular membranes, detergents or as emulsification agents. Due to their amphiphilic properties, they cannot only mediate between two domains of very different solvent compatibility like water and organic but also show fascinating self-assembly features resulting in micelles, vesicles, or lyotropic liquid crystals. The current review article highlights some approaches towards the next generation surfactants, for example, those with catalytically active heads. Furthermore, it is shown that amphiphilic properties can be obtained beyond the classical hydrophobic-hydrophilic interplay, for instance with surfactants containing one molecular block with a special shape. Whereas, classical surfactants are static, researchers have become more interested in species that are able to change their properties depending on external triggers. The article discusses examples for surfactants sensitive to chemical (e.g., pH value) or physical triggers (temperature, electric and magnetic fields).