Ferrocene Groups Tethered to Clay Surfaces

Swearingen, Carla B.; Macha, Susan; Fitch, Alanah

doi:10.1149/1.1455650

Cited by 5 publications

(3 citation statements)

References 32 publications

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“…In spite of the increasing interest of modified clays for electroanalytical purposes, there are rather few reports in literature dealing with surfactant-clay film electrodes. Yet, Swearingen and co-workers have reported the intercalation of a series of ferrocenyl surfactants into a clay film, in an attempt to study the rate of the process regarding the chain length of the surfactants [42]. Falaras & Petridis have also reported the preparation of CMEs by the coating of cetyltrimethylammonium bromide, that were successfully used for the incorporation and binding of anionic species [43].…”

Section: Introductionmentioning

confidence: 99%

Permselective and Preconcentration Properties of a Surfactant‐Intercalated Clay Modified Electrode

et al. 2006

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This work is focused on the voltammetric examination of the ion exchange properties of a smectite type clay, before and after its modification by the replacement of its native interlamellar cations (Na) by hexadecyltrimethylammonium cations (HDTMA þ ). The raw clay and its organically modified form were first characterized by X-ray diffraction (XRD) and N 2 adsorption -desorption isotherms (BET method) that confirmed the modification via an intercalation process. These materials were subsequently coated onto glassy carbon surfaces, and the resulting modified electrodes were evaluated for the uptake of [Ru(NH 3 ) 6 ] 3þ and [Fe(CN) 6 ] 3À ions used as redox probes. Some experimental parameters affecting the incorporation of the probes within the film, including the ionic strength, the surfactant loading and the solution pH are thoroughly examined, in order to highlight the mechanism of the process. The possibility of using the surfactant-intercalated clay modified electrode as an electrochemical sensor for [Fe(CN) 6 ] 3À is also evaluated.

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Section: Introductionmentioning

confidence: 99%

Permselective and Preconcentration Properties of a Surfactant‐Intercalated Clay Modified Electrode

et al. 2006

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“…Several F n TAB surfactants have been described in literature but, in most cases, with n ≥ 8 . We first synthesized a shorter-chain F n TAB surfactant with n = 6, which, to our knowledge, was mentioned in only two reports , devoted to the electroactivity of F 6 TAB-tethered clay, where the surfactant was obtained with a multistep synthesis and its interfacial properties were not documented. In our case, F 6 TAB was obtained in a single step by Hofmann alkylation of the bromide precursor (Figure A, full protocol in Materials and methods).…”

Section: Resultsmentioning

confidence: 99%

Redox Control of Particle Deposition from Drying Drops

Galy

Guitton-Spassky

Sella

et al. 2022

ACS Appl. Mater. Interfaces

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The coffee-ring effect (CRE), which denotes the accumulation of nonvolatile compounds at the periphery of a pinned sessile drying drop, is a universal and ubiquitous yet complex phenomenon. It is crucial to better understand and control it, either to avoid its various deleterious consequences in many processes requiring homogeneous deposition or to exploit it for applications ranging from controlled particle patterning to low cost diagnostics. Here, we report for the first time the use of a reduction–oxidation (redox) stimulus to cancel the CRE or harness it, leading to a robust and tunable control of particle deposition in drying sessile drops. This is achieved by implementing redox-sensitive ferrocenyl cationic surfactants of different chain lengths in drying drops containing anionic colloids. Varying surfactant hydrophobicity, concentration, and redox state allows us not only to control the overall distribution of deposited particles, including the possibility to fully cancel the CRE, but also to modify the microscopic organization of particles inside the deposit. Notably, with all other parameters being fixed, this method allows the adjustment of the deposited particle patterns, from polycrystalline rings to uniform disks, as a function of the oxidation rate. We show that the redox control can be achieved either chemically by the addition of oxidants or electrochemically by applying a potential for additive-free and reversible actuation in a closed system. This correlation between the redox state and the particle pattern opens a perspective for both redox-programmable particle patterning and original diagnostic applications based on the visual determination of a redox state. It also contributes to clarify the role of surfactant charge and its amphiphilic character in directing particle deposition from drying suspensions.

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“…In this paper, we report the results of a study in which we sought to demonstrate that it is possible to control polymer−surfactant interactions by using redox-active surfactants in combination with electrochemical methods. The study is based on the redox-active surfactant (11-ferrocenylundecyl)trimethylammonium bromide (FTMA, seen in Figure a). − This surfactant forms micelles at concentrations above 0.1 mM in aqueous solutions containing 0.1 M Li 2 SO 4 at pH 2 and 25 °C. , These micelles can be disassembled by oxidation of the ferrocene group within the surfactant to a ferrocenium ion. Past studies have established that the oxidation and disassembly of micelles is reversible. , We hypothesized that changes in the self-assembly of FTMA with oxidation state would change the interactions of FTMA with polymers such as ethyl(hydroxyethyl) cellulose (EHEC) in solution.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Control of the Interactions of Polymers and Redox-Active Surfactants

Hays

Abbott

2005

Langmuir

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We report the characterization of aqueous solutions (0.1 M Li(2)SO(4)) of dilute ethyl(hydroxyethyl) cellulose (EHEC) mixed with the redox-active surfactant (11-ferrocenylundecyl)trimethylammonium bromide (FTMA) by measurements of clouding temperatures and dynamic light scattering. The investigation sought to test the hypothesis that FTMA, which forms micelles in aqueous solution in its reduced state but not in its oxidized state, would permit reversible control over the formation of polymer-surfactant complexes in solution. Our measurements revealed that low concentrations of reduced FTMA enhance aggregation, whereas high concentrations of reduced FTMA disperse polymer-surfactant aggregates. This behavior is qualitatively similar to both dodecyltrimethylammonium bromide and sodium dodecyl sulfate and reflects cooperative interactions between FTMA and EHEC. In contrast, oxidized FTMA was found not to promote EHEC aggregation at low concentrations of oxidized FTMA nor disperse EHEC aggregates at high concentrations. Measurements of dynamic light scattering revealed that the reduction of oxidized FTMA in solutions of EHEC containing 0.1-0.3 mmolal FTMA causes an increase in the sizes of polymer-surfactant aggregates of more than 1 order of magnitude. Our cloud point measurements also revealed that clouding can be induced isothermally via the electrochemical reduction of oxidized FTMA at room temperature at FTMA concentrations between 0.4 and 10 mmolal. In contrast, at concentrations of FTMA greater than 15 mmolal, the reduction of oxidized FTMA induces the clearing of EHEC solutions. We conclude that aggregation of EHEC in dilute solutions can be controlled by the manipulation of the oxidation state of FTMA.

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Ferrocene Groups Tethered to Clay Surfaces

Cited by 5 publications

References 32 publications

Permselective and Preconcentration Properties of a Surfactant‐Intercalated Clay Modified Electrode

Permselective and Preconcentration Properties of a Surfactant‐Intercalated Clay Modified Electrode

Redox Control of Particle Deposition from Drying Drops

Electrochemical Control of the Interactions of Polymers and Redox-Active Surfactants

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