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作者： S. Drew Storya，Stephen Boggsa，Linda M.Guineyb，Mani Rameshb，Mark C.Hersamb，C. Jeffrey Brinkerc，Sharon L.Walkerad
aDepartment of Chemical and Environmental Engineering, University of California, Riverside, CA, USA
bDepartments of Materials Science and Engineering, Chemistry, and Medicine, Northwestern University, Evanston, IL, USA
cDepartment of Chemical and Biological Engineering, University of New Mexico, Albuquerque, NM, USA
dDepartment of Civil, Architectural, and Environmental Engineering, Drexel University, Philadelphia, PA, USA
摘要：In this investigation, the utility of a static light scattering (SLS) technique to characterize aggregate morphology of two-dimensional engineered nanomaterials (2D ENMs) was systematically evaluated. The aggregation of graphene oxide (GO) and lithiated-molybdenum disulfide (Li-MoS2) were measured and compared to that of a spherical reference colloid, carboxylate-modified latex (CML) nanoparticles. The critical coagulation concentration (CCC) for all dispersions was determined via analysis of aggregation kinetics using time-resolved dynamic light scattering. This technique allowed for the elucidation of the transition from the reaction-limited aggregation (RLA) regime to diffusion-limited aggregation (DLA). The findings of this study support the aggregation trends predicted by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and recent computer simulations of aggregation kinetics. For all nanomaterials, as ionic strength increased towards the respective the CCC, fractal dimension decreased; any increase in ionic strength beyond the CCC did not yield significant change in fractal dimension. Across comparable primary particle sizes and using both carbonaceous (GO) and inorganic (Li-MoS2) 2D ENMs, this study further supports the use of SLS for the measurement of fractal dimension for 2D materials. To further support this claim, the aggregate morphology of GO in both RLA and DLA regimes was measured via cryogenic transmission electron microscopy.
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