Adsorption and Aggregation of C8E4 and C8G1 Nonionic Surfactants on Hydrophilic Silica Studied by Calorimetry

Király, Zoltán; Börner, Ralph; Findenegg, Gerhard H.

doi:10.1021/la9620768

Cited by 78 publications

(114 citation statements)

References 67 publications

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“…Liquid titration calorimetry is a microcalorimetric batch technique most often used to study the mechanism of solute adsorption onto solids from binary dilute solution [83,85,86]. It differs from the flow variant in that a stock solution is injected into the calorimetric cell where the solid sample is kept in homogeneous suspension in a liquid (solvent or solution).…”

Section: Model Of Batch Calorimetry Experimentsmentioning

confidence: 99%

Calorimetry at the Solid–Liquid Interface

Zając

2013

Calorimetry and Thermal Methods in Catalysis

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Broad principles of Solid-Liquid calorimetry together with some illustrative examples of its use in the field of catalysis are presented here. The first use is related to the determination of surface properties of catalysts, adsorbents and solid materials in contact with liquids. In particular, it is shown how to evaluate the capacity of a given solid to establish different types of interaction with its liquid environment or to calculate its specific surface area accessible to liquids. The second use includes the measurement of the heat effects accompanying catalytic reactions and the related interfacial phenomena at Solid-Liquid and Liquid-Liquid interfaces. Examples of competitive ion adsorption from dilute aqueous solutions, as well as the formation of surfactant aggregates either in aqueous solution or at the SolidLiquid interface are considered in view of potential applications in Environmental Remediation and Micellar Catalysis.

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Section: Model Of Batch Calorimetry Experimentsmentioning

confidence: 99%

Calorimetry at the Solid–Liquid Interface

Zając

2013

Calorimetry and Thermal Methods in Catalysis

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“…Experiments on both hydrophilic (silica) 16,17,18 and hydrophobic (graphite) 15,19 surfaces show that the adsorption is strongly exothermic at very low surface coverages but becomes weakly exothermic or even endothermic at coverages exceeding -10% of saturation. The former step is therefore energy-driven and should be dominated by surfactant-surface interactions (since the coverage is very low), whereas the latter step is more entropydriven and should be dominated by intermolecular interactions.…”

Section: Calorimetrymentioning

confidence: 99%

Supramolecular Structure of Surfactants Confined to Interfaces

Manne¹,

Warr²

1999

ACS Symposium Series

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The mounting evidence for the existence of surfactant aggregates at solid/solution interfaces prompts a re-examination of common experimental techniques for studying surfactant adsorption. The simple models of a surfactant monolayer or bilayer, while reasonable in the face of older experimental data, are now seen to be inadequate to describe the rich range of order seen by atomic force microscopy and other techniques. In this manuscript we review the results of atomic force microscopy which demonstrate the existence of surface micelles, look again at the experimental results which pointed towards surface aggregates, and also look ahead at how the existence of surface micelles requires us to revise the interpretation of other experimental studies and our entire picture of adsorbed films.

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“…The onset of the blue shift of l max of NR with 2 occurred at 8.0 mM, which is in nice agreement with the reported value for the cmc of 2 (8.4 mM). 11 Interestingly, the hydrophobic microdomains in aqueous solutions of 3 are already formed at a concentration around 0.01 mM, which is more than two orders of magnitude lower than with surfactant 2, clearly showing that the gelator segment contributes significantly to the stability of the hydrophobic domains.…”

mentioning

confidence: 95%

“…The surfactant segment used in this study is based on tetraethylene glycol mono-octyl ether 2 which self-assembles into micelles above a critical micelle concentration (cmc) of 8.4 mM due to hydrophobic interactions. 11 Previous work showed that self-assembly of non-ionic surfactants and cyclohexanetrisamide based hydrogelators like 1 are orthogonal processes. 8a Multisegment amphiphile 3 was constructed by the covalent connection of 1 and 2 (ESIw).…”

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confidence: 99%

Size control and compartmentalization in self-assembled nano-structures of a multisegment amphiphile

et al. 2010

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A ''multisegment amphiphile'' has been synthesized by covalently connecting two well known building blocks, a gelator and a micelle forming surfactant. Self-assembly results in the formation of compartmentalized nano-object displaying properties inherited from both parents.Amphiphiles continue to attract widespread attention in science and technology, not only because of their fascinating self-assembly properties, but also because their numerous, diverse applications in e.g. detergent formulations, catalysis, and drug delivery. Despite their large chemical diversity, amphiphiles share a common structure consisting of a hydrophilic and a hydrophobic segment, giving rise to a limited range of morphologies like micelles, vesicles, bilayers, and the corresponding inverted phases. 1 More recently, other building blocks such as small molecule gelators and peptides have been used to construct novel self-assembled architectures like ribbons, helices and tubes 2 with regular, well-defined structural features at molecular length scales. 3 Nevertheless, small molecule based self-assembled structures cannot yet compete with the sophisticated architectures found in natural systems, especially with regard to the levels of compartmentalization, size control, and hierarchical structure formation. 4 Currently, such multicompartment structures of defined size and 3-50 nm structural features can most easily be fabricated by controlled phase separation of multiple covalently connected segments in block copolymers, giving rise to a variety of multicompartment assemblies 5 and hierarchically structured materials. 6 Only few examples have been reported of self-assembled structures from small molecules with a block structure. 7 The challenge remains to develop self-assembling systems based on small molecules that allow size control, hierarchical structure formation and compartmentalization at (sub)-molecular length scales. Previously we and others showed that the orthogonal self-assembly of certain hydrogelators and surfactants is a valid strategy towards new nanoarchitectures, including selfassembled interpenetrating networks and various organizations of vesicles or micelles with fibrous networks (Scheme 1a). 8,9 We anticipated that the covalent connection of two orthogonally self-assembling molecular building blocks would give rise to microphase separation phenomena at the molecular length scale.Here we present a first example of such a ''multisegment amphiphile'', as the small molecule counterpart of block copolymers (Scheme 1b). We found that this multisegment amphiphile self-assembles into well-defined aggregates with compartments and structural features at molecular length scales inherited from its parent compounds. Our results suggest that this behavior results from strong spatial constraints on a phase separating system at the molecular scale.A first requirement for a multisegment amphiphile is that the self-assembly of each segment is driven by incompatible interactions. In this study we have combined a low-molecularweight ...

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Adsorption and Aggregation of C₈E₄ and C₈G₁ Nonionic Surfactants on Hydrophilic Silica Studied by Calorimetry

Cited by 78 publications

References 67 publications

Calorimetry at the Solid–Liquid Interface

Calorimetry at the Solid–Liquid Interface

Supramolecular Structure of Surfactants Confined to Interfaces

Size control and compartmentalization in self-assembled nano-structures of a multisegment amphiphile

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