S Vera-López1, P Martínez2, M P San Andrés2, A M Díez-Pascual2, M Valiente2. 1. Department of Analytical Chemistry, Physical Chemistry, and Chemical Engineering, University of Alcalá, 28871 Madrid, Spain. Electronic address: soledad.vera@uah.es. 2. Department of Analytical Chemistry, Physical Chemistry, and Chemical Engineering, University of Alcalá, 28871 Madrid, Spain.
Abstract
HYPOTHESIS: Aqueous solutions of ionic surfactants allow the exfoliation of graphene, that can be explained considering the adsorption model of ionic surfactants to hydrophobic surfaces. For many years, pyrene has been used as a fluorescent probe because its sensitivity to the micro-environment. The study of pyrene fluorescence in the presence of different graphene dispersions in an ionic surfactant, would improve the knowledge of the graphene-surfactant interactions. EXPERIMENTS: Different dispersions of graphene in sodium dodecylsulfate were prepared at different weight ratios 0.5, 1 and 2%. The dispersions have been studied by Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The influence of the dispersions on the pyrene fluorescence has been investigated. FINDINGS: The graphene sheets modified by the surfactant quench the fluorescence of pyrene, which depends on the amount of graphene, the concentration of surfactant and the weight ratio. For surfactant concentrations below the critical micelle concentration, the quenching effect is higher as the weight ratio increases. Once this concentration is reached, the fluorescence increases slightly and then levels off. This behavior has been explained by the adsorption model. For a constant surfactant concentration, two straight lines can be observed in the Stern-Volmer plots whose cut-off point is approximately 20 mg L-1 of graphene.
HYPOTHESIS: Aqueous solutions of ionic surfactants allow the exfoliation of graphene, that can be explained considering the adsorption model of ionic surfactants to hydrophobic surfaces. For many years, pyrene has been used as a fluorescent probe because its sensitivity to the micro-environment. The study of pyrene fluorescence in the presence of different graphene dispersions in an ionic surfactant, would improve the knowledge of the graphene-surfactant interactions. EXPERIMENTS: Different dispersions of graphene in sodium dodecylsulfate were prepared at different weight ratios 0.5, 1 and 2%. The dispersions have been studied by Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The influence of the dispersions on the pyrene fluorescence has been investigated. FINDINGS: The graphene sheets modified by the surfactant quench the fluorescence of pyrene, which depends on the amount of graphene, the concentration of surfactant and the weight ratio. For surfactant concentrations below the critical micelle concentration, the quenching effect is higher as the weight ratio increases. Once this concentration is reached, the fluorescence increases slightly and then levels off. This behavior has been explained by the adsorption model. For a constant surfactant concentration, two straight lines can be observed in the Stern-Volmer plots whose cut-off point is approximately 20 mg L-1 of graphene.
Authors: Rocío Mateos; Alba García-Zafra; Soledad Vera-López; María Paz San Andrés; Ana María Díez-Pascual Journal: Materials (Basel) Date: 2018-05-25 Impact factor: 3.623
Authors: María Paz San Andrés; Marina Baños-Cabrera; Lucía Gutiérrez-Fernández; Ana María Díez-Pascual; Soledad Vera-López Journal: Int J Mol Sci Date: 2021-05-17 Impact factor: 5.923