I-SURF : Inorganic surfactants with multifunctinal heads

Institutions
  • Department of Chemistry
Publications
    Lanz, Cornelia; Schlötter, Moritz; Klinkenberg, Nele; Besirske, Patricia; Polarz, Sebastian (2020): Stimuli-Responsive Particle-Based Amphiphiles as Active Colloids Prepared by Anisotropic Click Chemistry Angewandte Chemie International Edition. Wiley. 2020, 59(23), pp. 8902-8906. ISSN 1433-7851. eISSN 1521-3773. Available under: doi: 10.1002/anie.202001423

Stimuli-Responsive Particle-Based Amphiphiles as Active Colloids Prepared by Anisotropic Click Chemistry

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Amphiphiles alter the energy of surfaces, but the extent of this feature is typically constant. Smart systems with amphiphilicity as a function of an external, physical trigger are desirable. As a trigger, the exposure to a magnetic field, in particular, is attractive because it is not shielded in water. Amphiphiles like surfactants are well known, but the magnetic response of molecules is typically weak. Vice‐versa, magnetic particles with strong response to magnetic triggers are fully established in nanoscience, but they are not amphiphilic. In this work colloids with Janus architecture and ultra‐small dimensions (25 nm) have been prepared by spatial control over the thiol‐yne click modification of organosilica‐magnetite core–shell nanoparticles. The amphiphilic properties of these anisotropically modified particles are proven. Finally, a pronounced and reversible change in interfacial stabilization results from the application of a weak (<1 T) magnetic field.

Origin (projects)

    Kunkel, Marius; Bitter, Stefan; Sailer, Frank; Winter, Rainer F.; Polarz, Sebastian (2020): Aggregation‐Induced Improvement of Catalytic Activity by Inner‐Aggregate Electronic Communication of Metal‐Fullerene‐Based Surfactants ChemCatChem. Wiley. 2020, 12(10), pp. 2726-2731. ISSN 1867-3880. eISSN 1867-3899. Available under: doi: 10.1002/cctc.202000412

Aggregation‐Induced Improvement of Catalytic Activity by Inner‐Aggregate Electronic Communication of Metal‐Fullerene‐Based Surfactants

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A paradigm for active constituents in (homogeneous) catalysis is that optimum performance requires maximum dispersion. Generally, aggregation results in a decline. This is a different case in supramolecular catalysis. A new concept based on surfactants equipped with functional heads is presented, which becomes a more active catalyst itself upon aggregation. The head group of the surfactants is composed of a diethylenetriamine‐functionalized fullerene capable of coordinating to catalytically active metals like Co II . The improvement of catalytic properties upon aggregation is demonstrated via electrocatalytic water‐splitting reaction as a model system. Detailed electrochemistry studies were performed at concentrations below and above the critical aggregation concentration (cac). While isolated surfactant molecules represent only moderately active catalysts, drastic improvement of efficiency in the hydrogen evolution (HER) as well as in the oxygen evolution reactions (OER) were detected, once vesicular structures have formed. Self‐organization of the surfactants leads to an increase in turnover frequencies of up to 1300% (HER). The strongly beneficial effect of aggregation arises from the favorable alignment of individual molecules, thus, facilitating intermolecular charge transfer processes in the vesicles.

Origin (projects)

    Donner, Adrian; Trepka, Bastian; Theiss, Sebastian; Immler, Fabian; Traber, Johanna; Polarz, Sebastian (2019): NCH-Metallosurfactants as Active Polymerization Catalysts Langmuir. 2019, 35(50), pp. 16514-16520. ISSN 0743-7463. eISSN 1520-5827. Available under: doi: 10.1021/acs.langmuir.9b02152

NCH-Metallosurfactants as Active Polymerization Catalysts

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Next-generation surfactants provide extended functionality apart from their amphiphilic properties. We present two novel metallosurfactants characterized by a N-heterocyclic carbene (NHC) head bearing Cu(I) and Fe(II). An innovative approach for their application in emulsion polymerizations under 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 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 co-polymerization with styrene via macroinitiation and PMMA-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.

Origin (projects)

    Kunkel, Marius; Sutter, Sebastian; Polarz, Sebastian (2019): Molecular Semiconductor Surfactants with Fullerenol Head and Colored Tails for Photoconversion of Carbon Dioxide Angewandte Chemie International Edition. 2019, 58(44), pp. 15620-15625. ISSN 0570-0833. eISSN 1521-3773. Available under: doi: 10.1002/anie.201905410

Molecular Semiconductor Surfactants with Fullerenol Head and Colored Tails for Photoconversion of Carbon Dioxide

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The leaf is paramount for a material converting waste (CO2) to value with maximum sustainability. As the most important constituent, it contains the coupled photosystems II and I imbedded in the cellular membrane of chloroplasts. Can key functions of the leaf be packed in soap? We present next generation surfactants, which self-assemble to bilayer vesicles (similar to the cellular membrane), are able to absorb photons of two different VIS-wavelengths and exchange excited charge carriers (similar to the photosystems), followed by conversion of CO2 (in analogy to the leaf). The amphiphiles contain five dye molecules as the hydrophobic entity attached exclusively to one hemisphere of a polyhydroxylated fullerene (Janus-type). The manuscript reports surfactant, optical, electronic and catalytic properties. Photons adsorbed by the dyes become transferred to the fullerenol head, where they are able react with different species like with CO2 to formic acid.

Origin (projects)

    Sutter, Sebastian; Trepka, Bastian; Siroky, Stephan; Hagedorn, Kay; Theiss, Sebastian; Baum, Peter; Polarz, Sebastian (2019): Light-Triggered Boost of Activity of Catalytic Bola-Type Surfactants by a Plasmonic Metal-Support Interaction Effect ACS Applied Materials & Interfaces. 2019, 11(17), pp. 15936-15944. ISSN 1944-8244. eISSN 1944-8252. Available under: doi: 10.1021/acsami.9b03727

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

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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 (Cn) 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.

Origin (projects)

    Kunkel, Marius; Polarz, Sebastian (2019): Easy, efficient and versatile one-pot synthesis of Janus-type-substituted fullerenols Beilstein journal of organic chemistry. 2019, 15, pp. 901-905. ISSN 2195-951X. eISSN 1860-5397. Available under: doi: 10.3762/bjoc.15.87

Easy, efficient and versatile one-pot synthesis of Janus-type-substituted fullerenols

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An efficient one-pot synthesis for Janus-type fullerenol derivatives and how to characterize them is reported. This synthesis provides access to asymmetrically substituted fullerenol with five substituents on one pole of the fullerene and polyhydroxylation moieties, mostly ether and hydroxy groups, on the rest of the fullerene core. As substituents a broad variety of primary amines can be used to obtain Janus-type amphiphilic fullerenols in good to excellent yield. These fullerenol amphiphiles can serve as suitable precursors for further reactions resulting in new applications for fullerenols.

Origin (projects)

    Polarz, Sebastian; Kunkel, Marius; Donner, Adrian; Schlötter, Moritz (2018): Added-Value Surfactants Chemistry - A European Journal. 2018, 24(71), pp. 18842-18856. ISSN 0947-6539. eISSN 1521-3765. Available under: doi: 10.1002/chem.201802279

Added-Value Surfactants

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Surfactants are ubiquitous in cellular membranes, detergents or as emulsification agents. Due to their amphiphilic properties, they can not 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, e.g. 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, one became more and more interested in species, which 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).

Origin (projects)

    Bitter, Stefan; Kunkel, Marius; Burkart, Lisa; Mang, André; Winter, Rainer F.; Polarz, Sebastian (2018): Organometallic, Nonclassical Surfactant with Gemini Design Comprising π-Conjugated Constituents Ready for Modification ACS Omega. 2018, 3(8), pp. 8854-8864. eISSN 2470-1343. Available under: doi: 10.1021/acsomega.8b01405

Organometallic, Nonclassical Surfactant with Gemini Design Comprising π-Conjugated Constituents Ready for Modification

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Surfactants are functional molecules comprising a water-compatible head group and a hydrophobic tail. One of their features is the formation of self-assembled structures in contact with water, for instance, micelles, vesicles, or lyotropic liquid crystals. One way to increase the functionality of surfactants is to implement moieties containing transition-metal species. Ferrocene-based surfactants represent an excellent example because of the distinguished redox features. In most existing ferrocene-based amphiphiles, an alkyl chain is classically used as the hydrophobic tail. We report the synthesis and properties of 1-triisopropylsilylethynyl-1′-trimethylammoniummethylferrocene (FcNMe3TIPS). In FcNMe3TIPS, ferrocene is part of the head group (Gemini design) but is also attached to a (protected) π-conjugated ethynyl group. Although this architecture differs from that of classical amphiphiles and those of other ferrocene-based amphiphiles, the compound shows marked surfactant properties comparable to those of lipids, exhibiting a very low value of critical aggregation concentration in water (cac = 0.03 mM). It forms classical micelles only in a very narrow concentration range, which then convert into monolayer vesicles. Unlike classical surfactants, aggregates already form at a very low concentration, far beneath that required for the formation of a monolayer at the air–water interface. At even higher concentration, FcNMe3TIPS forms lyotropic liquid crystals, not only in contact with water, but also in a variety of organic solvents. As an additional intriguing feature, FcNMe3TIPS is amenable to a range of further modification reactions. The TIPS group is easily cleaved, and the resulting ethynyl function can be used to construct heterobimetallic platinum-ferrocene conjugates with trans-Pt(PEt3)2X (X = Cl, I) complex entities, leading to a heterobimetallic surfactant. We also found that the benzylic α-position of FcNMe3TIPS is rather reactive and that the attached ammonium group can be exchanged by other substituents (e.g., −CN), which offers additional opportunities for further functionalization. Although FcNMe3TIPS is reversibly oxidized in voltammetric and UV–vis spectroelectrochemical experiments, the high reactivity at the α-position is also responsible for the instability of the corresponding ferrocenium ion, leading to a polymerization reaction.

Origin (projects)

  Kunkel, Marius; Schildknecht, Stefan; Boldt, Klaus; Zeyffert, Lukas; Schleheck, David; Leist, Marcel; Polarz, Sebastian (2018): Increasing the Resistance of Living Cells against Oxidative Stress by Nonnatural Surfactants as Membrane Guards ACS applied materials & interfaces. 2018, 10(28), pp. 23638-23646. ISSN 1944-8244. eISSN 1944-8252. Available under: doi: 10.1021/acsami.8b07032

Increasing the Resistance of Living Cells against Oxidative Stress by Nonnatural Surfactants as Membrane Guards

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The importation of construction principles or even constituents from biology into materials science is a prevailing concept. Vice versa, the cellular level modification of living systems with nonnatural components is much more difficult to achieve. It has been done for analytical purposes, for example, imaging, to learn something about intracellular processes. Cases describing the improvement of a biological function by the integration of a nonnatural (nano)constituent are extremely rare. Because biological membranes contain some kind of a surfactant, for example, phospholipids, our idea is to modify cells with a newly synthesized surfactant. However, this surfactant is intended to possess an additional functionality, which is the reduction of oxidative stress. We report the synthesis of a surfactant with Janus-type head group architecture, a fullerene C60 modified by five alkyl chains on one side and an average of 20 oxygen species on the other hemisphere. It is demonstrated that the amphiphilic properties of the fullerenol surfactant are similar to that of lipids. Not only quenching of reactive oxygen species (superoxide, hydroxyl radicals, peroxynitrite, and hydrogen peroxide) was successful, but also the fullerenol surfactant exceeds benchmark antioxidant agents such as quercetin. The surfactant was then brought into contact with different cell types, and the viability even of delicate cells such as human liver cells (HepG2) and human dopaminergic neurons (LUHMES) has proven to be extraordinarily high. We could show further that the cells take up the fullerenol surfactant, and as a consequence, they are protected much better against oxidative stress.

Origin (projects)

  Klaiber, Alexander; Kollek, Tom; Cardinal, Simon; Hug, Nicolas; Drechsler, Markus; Polarz, Sebastian (2018): Electron Transfer in Self-Assembled Micelles Built by Conductive Polyoxometalate-Surfactants Showing Battery-Like Behavior Advanced Materials Interfaces. 2018, 5(8), 1701430. eISSN 2196-7350. Available under: doi: 10.1002/admi.201701430

Electron Transfer in Self-Assembled Micelles Built by Conductive Polyoxometalate-Surfactants Showing Battery-Like Behavior

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An ideal material for the storage of electrical energy is characterized by high specific energy and high specific power at the same time, which is a task of enormous difficulty. The so-called redox flow battery is a highly promising approach. This new energy storage technology is based on two half-cells containing dissolved electrochemically active species. Compared to conventional, static accumulators it is not only engineered in a unique way but also needs a tailor-made basis of chemical materials. Therefore, many different redox-active materials are being investigated. However, research is focused mainly on the redox properties, not taking possible synergistic effects arising from self-assembled structures into account. Here, a novel surfactant is presented containing an electroactive polyoxometalate (POM) head connected to anthraquinone (AQ) as the relevant electron reservoir via a π-conjugated chain. When organized into micelles, electrons put on the POM corona “slide” into their depot inside the micellar core until needed. Cyclic voltammetry proves the high reversibility and stability of this system, which therefore can be regarded as micellar energy storage.

Origin (projects)

    Voggel, Michael; Meinusch, Rebecca M.; Siewert, Vanessa; Kunkel, Marius; Wittmann, Valentin; Polarz, Sebastian (2018): Sweet surfactants : packing parameter-invariant amphiphiles as emulsifiers and capping agents for morphology control of inorganic particles Soft Matter. 2018, 14(35), pp. 7214-7227. ISSN 1744-683X. eISSN 1744-6848. Available under: doi: 10.1039/c8sm01091a

Sweet surfactants : packing parameter-invariant amphiphiles as emulsifiers and capping agents for morphology control of inorganic particles

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Surfactants are not only pivotal constituents in any biological organism in the form of phospholipids, they are also essential for numerous applications benefiting from a large, internal surface, such as in detergents, for emulsification purposes, phase transfer catalysis or even nanoparticle stabilization. A particularly interesting, green class of surfactants contains glycoside head groups. Considering the variability of glycosides, a large number of surfactant isomers become accessible. According to established models in surfactant science such as the packing parameter or the hydrophilic lipophilic balance (HLB), they do not differ from each other and should, thus, have similar properties. Here, we present the preparation of a systematic set of glycoside surfactants and in particular isomers. We investigate to which extent they differ in several key features such as critical aggregation concentration, thermodynamic parameters, etc. Analytical methods like isothermal titration calorimetry (ITC), tensiometry, dynamic light scattering (DLS), small angle-X-ray scattering (SAXS), transmission electron microscopy (TEM) and others were applied. It was found that glycosurfactant isomers vary in their emulsification properties by up to two orders of magnitude. Finally, we have investigated the role of the surfactants in a microemulsion-based technique for the generation of zinc oxide (ZnO) nanoparticles. We found that the choice of the carbohydrate head has a marked effect on the shape of the formed inorganic nanocrystals.

Origin (projects)

    Donner, Adrian; Hagedorn, Kay; Mattes, Lorenz; Drechsler, Markus; Polarz, Sebastian (2017): Hybrid Surfactants with N-Heterocyclic Carbene Heads as a Multifunctional Platform for Interfacial Catalysis Chemistry - A European Journal. 2017, 23(72), pp. 18129-18133. ISSN 0947-6539. eISSN 1521-3765. Available under: doi: 10.1002/chem.201703902

Hybrid Surfactants with N-Heterocyclic Carbene Heads as a Multifunctional Platform for Interfacial Catalysis

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Processing of substrates with different solvent compatibility is a persistent problem in homogeneous catalysis, in particular when one starting compound is water soluble and the other is not. A promising concept reported in the literature is micellar catalysis. However, the process of developing catalysts that are surfactants at the same time is still in its early stages. We report the synthesis of a new surfactant system with an N-heterocyclic carbene (NHC) moiety as a head group. Characteristic surfactant properties such as the formation of micelles or liquid crystals is documented. The new surfactant ligand forms coordination compounds with various metals, most importantly Pd2+ , in square planar geometry. In addition, the Pd-NHC compound shows surfactant features, and can be used successfully for C-C cross-coupling reactions (Suzuki, Heck). The boost in catalytic activity by one order of magnitude compared to analogous but non-amphiphilic species is reported.

Origin (projects)

    Hermann, Stefanie; Wessig, Martin; Kollofrath, Dennis; Gerigk, Melanie; Hagedorn, Kay; Odendal, James A.; Hagner, Matthias; Drechsler, Markus; Erler, Philipp; Fonin, Mikhail; Maret, Georg; Polarz, Sebastian (2017): Magneto-Adaptive Surfactants Showing Anti-Curie Behavior and Tunable Surface Tension as Porogens for Mesoporous Particles with 12-Fold Symmetry Angewandte Chemie International Edition. 2017, 56(20), pp. 5475-5479. ISSN 1433-7851. eISSN 1521-3773. Available under: doi: 10.1002/anie.201612416

Magneto-Adaptive Surfactants Showing Anti-Curie Behavior and Tunable Surface Tension as Porogens for Mesoporous Particles with 12-Fold Symmetry

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Gaining external control over self-organization is of vital importance for future smart materials. Surfactants are extremely valuable for the synthesis of diverse nanomaterials. Their self-assembly is dictated by microphase separation, the hydrophobic effect, and head-group repulsion. It is desirable to supplement surfactants with an added mode of long-range and directional interaction. Magnetic forces are ideal, as they are not shielded in water. We report on surfactants with heads containing tightly bound transition-metal centers. The magnetic moment of the head was varied systematically while keeping shape and charge constant. Changes in the magnetic moment of the head led to notable differences in surface tension, aggregate size, and contact angle, which could also be altered by an external magnetic field. The most astonishing result was that the use of magnetic surfactants as structure-directing agents enabled the formation of porous solids with 12-fold rotational symmetry.

Origin (projects)

    Klaiber, Alexander; Polarz, Sebastian (2016): Passing Current through Electrically Conducting Lyotropic Liquid Crystals and Micelles Assembled from Hybrid Surfactants with π-Conjugated Tail and Polyoxometalate Head ACS Nano. 2016, 10(11), pp. 10041-10048. ISSN 1936-0851. eISSN 1936-086X. Available under: doi: 10.1021/acsnano.6b04677

Passing Current through Electrically Conducting Lyotropic Liquid Crystals and Micelles Assembled from Hybrid Surfactants with π-Conjugated Tail and Polyoxometalate Head

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The solvent-mediated ability for molecularly encoded self-assembly into states of higher order (micelles, lyotropic liquid crystals) embodies the basis for many applications of surfactants in science and society. Surfactants are used frequently in recipes for nanoparticle synthesis. Because ordinary surfactants comprise insulating constituents (alkyl groups as side-chains and charged organic heads), such nanostructures are wrapped in an electrically inactive barrier, and this is a large disadvantage for future developments in nanotechnology. Implications of micelles with electrically conducting walls made from either "metallic" or "semiconducting" surfactants are huge, also in other areas such as nanoelectrocatalysis or micellar energy storage. We cross this frontier by replacing not only the hydrophilic chain but also the hydrophilic head by electronically conducting entities. We report the synthesis of surfactants with oligo para-phenylene-ethynylene as a π-conjugated side-chain attached to a redox-active, inorganic polyoxometalate cluster as charged head. It is proven that electronic communication between head and tail takes place. Hybridization on the molecular level leads to the emergence of advanced surfactant features such as semiconductor properties (Egap = 2.6 eV) in soft lyotropic systems (micelles, liquid crystals).

Origin (projects)

    Klaiber, Alexander; Lanz, Cornelia; Landsmann, Steve; Gehring, Julia; Drechsler, Markus; Polarz, Sebastian (2016): Maximizing Headgroup Repulsion : Hybrid Surfactants with Ultrahighly Charged Inorganic Heads and Their Unusual Self-Assembly Langmuir. 2016, 32(42), pp. 10920-10927. ISSN 0743-7463. eISSN 1520-5827. Available under: doi: 10.1021/acs.langmuir.6b02661

Maximizing Headgroup Repulsion : Hybrid Surfactants with Ultrahighly Charged Inorganic Heads and Their Unusual Self-Assembly

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Non-equilibrium states of matter are arousing huge interest based on outstanding possibilities to generate unprecedented structures with novel properties. Self-organizing soft-matter is the ideal object of study as it unifies periodic order and high dynamics. Compared to settled systems it becomes vital to realize more complex interaction patterns. A promising and intricate approach is implementing controlled balance between attractive and repulsive forces. We try to answer a fundamental question in surfactant science: How are processes like lyotropic liquid crystals and micellization affected, when head group charge becomes so large that repulsive interactions are inevitable? A particular challenge is that size and shape of the surfactant must not change. We could realize the latter by means of new hybrid surfactants with a heteropolyanion head [EW11O39]n- (E = PV, SiIV, BIII; n = 3, 4, 5). Among the unusual self-assembled structures we report about micelles of a new type with dumbbell morphology.

Origin (projects)

    Klaiber, Alexander; Landsmann, Steve; Löffler, Tobias; Polarz, Sebastian (2016): Fourfold action of surfactants with superacid head groups : polyoxometalate-silicone nanocomposites as promising candidates for proton-conducting materials New Journal of Chemistry. 2016, 40(2), pp. 919-922. ISSN 1144-0546. eISSN 1369-9261. Available under: doi: 10.1039/C5NJ01544H

Fourfold action of surfactants with superacid head groups : polyoxometalate-silicone nanocomposites as promising candidates for proton-conducting materials

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Conventional, organic surfactants normally fulfill only one task associated with their amphiphilic character. The situation changes and multifunctionality is granted for surfactants containing inorganic entities, so-called I-SURFs. Here, we demonstrate that an I-SURF with a heteropolyacid head fulfills four tasks at once. It acts as an effective emulsification agent, it catalyzes the polymerization of silicone monomers, it provides proton-conductivity in a PDMS/polyoxometalate hybrid, and it acts as a precursor for a nanostructured WO3 material.

Origin (projects)

    Polarz, Sebastian; Odendal, James Arthur; Hermann, Stefanie; Klaiber, Alexander (2015): Amphiphilic hybrids containing inorganic constituent : More than soap Current Opinion in Colloid & Interface Science. 2015, 20(3), pp. 151-160. ISSN 1359-0294. eISSN 1879-0399. Available under: doi: 10.1016/j.cocis.2015.07.006

Amphiphilic hybrids containing inorganic constituent : More than soap

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Amphiphiles and surfactants are indispensable compounds in industry, scientific research and everyday life, such as emulsification agents, detergents, etc. The vast majority of currently used amiphiphiles are organic in nature, and are composed of two molecular parts joined together, one hydrophilic and one hydrophobic. The current article highlights some of the recent developments in the emerging field of hybrid amphiphiles, focusing on systems with at least one inorganic constituent. Different classes of amphiphiles can be defined, depending on if the inorganic entity is molecular or has particle character, and depending on the strength of interaction between the inorganic and organic phase. It is seen that in addition to typical amphiphilic properties, most importantly the formation of self-assembled structures like micelles or lyotropic liquid crystals, the hybrid amphiphiles exhibit additional, functional features like special magnetic or catalytic properties. Ultimately, systemic features can be observed, leading to the emergence of new properties which none of the constituents of hybrid amphiphile could have on its own.

Origin (projects)

    Polarz, Sebastian; Landsmann, Steve; Klaiber, Alexander (2014): Hybrid Surfactant Systems with Inorganic Constituents Angewandte Chemie International Edition. 2014, 53(4), pp. 946-954. ISSN 1433-7851. eISSN 1521-3773. Available under: doi: 10.1002/anie.201303159

Hybrid Surfactant Systems with Inorganic Constituents

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Surfactants are molecules of enormous scientific and technological importance, which are widely used as detergents, emulsifiers, and for the preparation of diverse nanostructures. Their fascinating ability to form self-organized structures, such as micelles or liquid crystals, originate from their amphiphilic architecture—a polar head group linked to a hydrophobic chain. While almost all known surfactants are organic, a new family of surfactants is now emerging, which combines amphiphilic properties with the advanced functionality of transition-metal building blocks, for example, redox or catalytic activity and magnetism. These hybrid surfactants exhibit novel self-organization features because of the unique size and electronic properties of the metal-containing entities.

Origin (projects)

Funding sources
Name Finanzierungstyp Kategorie Project no.
Europäische Union third-party funds research funding program 447/14
Further information
Period: 01.03.2014 – 28.02.2019