Electrochemical characterization of the hydrophobic microenvironment within gemini surfactant micellar-hybridized supramolecular gels

We proposed a new electrochemical strategy to characterize the hydrophobic microenvironment of micellar-hybridized supramolecular gels. The micellar-hybridized systems consist of micelles formed from gemini surfactants and supramolecular gels formed by self-assembly of the gelator N,N-dibenzoyl-l-cystine (DBC). SEM images indicated that the microscopic morphology of micellar-hybridized DBC gels possessed a denser three-dimensional network structure. An important feature of micellar-hybridized supramolecular gels is the presence of hydrophobic microdomains within the systems. The interaction of Methylene Blue (MB) and the hydrophobic microdomains can be quantitatively characterized by the net positive shifts of the redox formal potential (E0′) and the change of peak currents (ip) obtained from the cyclic voltammograms of MB. ΔE0′ between the micellar-hybridized DBC gel and non-hybridized gel was much larger than that between the micellar solution and aqueous solution, implying that the alteration of hydrophobicity of microdomains in hybrid system. By comparing the apparent diffusion coefficients of MB in the varied systems, it is indicative that the apparent diffusion coefficients of MB can be also employed to characterize the hydrophobicity change of hybrid systems. The fluorescent spectra of 1,8-anilinonaphthalenesulfonic acid within the hybrid gels further verified the results of the cyclic voltammograms. It is suggested that the cyclic voltammograms are a facile and sensitive method to monitor the hydrophobic microenvironment of the micellar-hybridized supramolecular gels.

Molecularly dispersed MB would be gradually solubilized into the hydrophobic microdomains under the synergy effect of micelles and entangled DBC fibers network. Because the redox reaction of MB can be influenced by the hydrophobic microdomains, the variation of hydrophobicity of the hybrid system can be estimated by measuring electrochemical behaviors of MB.Figure optionsDownload as PowerPoint slideHighlights
► Electrochemical characterization of hydrophobic microdomains of micellar-hybridized supramolecular gels.
► Redox reaction of Methylene Blue is response to change of hydrophobic microdomains MB located.
► Hydrophobicity variation of hybrid systems can be tuned by changing concentration and spacer length of gemini surfactants.
► Electrochemical strategy is sensitive and simple to qualitatively and quantitatively understand the hybrid systems at molecular level.