Dispersion Stability of Functionalized Graphene in Aqueous Sodium Dodecyl Sulfate Solutions

Citations Over TimeTop 11% of 2013 papers

Abstract

The colloidal stability of functionalized graphene sheets (FGSs) in aqueous sodium dodecyl sulfate (SDS) solutions of different concentrations was studied by optical microscopy and ultraviolet-visible light absorption after first dispersing the FGSs ultrasonically. In up to ∼10 μM SDS solutions, FGSs reaggregated within a few minutes, forming ramified structures in the absence of SDS and increasingly compact structures as the amount of SDS increased. Above ∼10 μM, the rate of reaggregation decreased with increasing SDS concentration; above ∼40 μM, the suspensions were colloidally stable for over a year. The concentration of ∼40 μM SDS lies 2 orders of magnitude below the critical surface aggregation concentration of ∼1.8 mM SDS on FGSs but above the concentration (∼18 μM) at which SDS begins to form a monolayer on FGSs. Neither surface micelle nor dense monolayer coverage is therefore required to obtain stable aqueous FGS dispersions. We support our experimental results by calculating the van der Waals and electrostatic interaction energies between FGSs as a function of SDS concentration and show that the experimentally observed transition from an unstable to a stable dispersion correlates with a transition from negative to positive interaction energies between FGSs in the aggregated state. Furthermore, our calculations support experimental evidence that aggregates tend to develop a compact structure over time.

Related Papers

• → The effect of micellar lifetime on the rate of solubilization and detergency in sodium dodecyl sulfate solutions(1993)71 cited
• → Micelle molecular weight of dodecyldimethylammonium chloride in aqueous solutions, and the transition of micelle shape in concentrated NaCl solutions(1980)115 cited
• → Separation and selectivity of benzophenones in micellar electrokinetic chromatography using sodium dodecyl sulfate micelles or sodium cholate modified mixed micelles(2001)18 cited
• → Atomistic Description of the Solubilisation of Testosterone Propionate in a Sodium Dodecyl Sulfate Micelle(2014)16 cited
• STUDY OF MICELLE FORMATION OF CTAB BY MICROCALORIMETRIC METHOD(2002)