Colloidal hybrid nanoparticles integrate two or more material domains into a single construct to achieve multifunctionality and synergistic properties. The synthesis of these complex multicomponent hybrid nanoparticles often yields size and composition distributions that subsequently impact observed properties and complicate structure-function studies. Analyses of nanoparticle systems such as these that contain multiple simultaneously occurring distributions are highly challenging. In this work, we introduce thermal field-flow fractionation (ThFFF) as an analytical method to separate and characterize iron oxide (Fe3O4), platinum (Pt), and multicomponent platinum-iron oxide (Pt-Fe3O4) hybrid nanoparticles by composition. The transport of matter by a temperature gradient or thermal diffusion is exploited in the ThFFF separation and characterization of inorganic nanoparticles. Thermal diffusion coefficient (DT) values are determined from measured ThFFF retention times and translational diffusion coefficients. The DT for pure Fe3O4 and pure Pt are found to bracket those determined for hybrid Pt-Fe3O4 nanoparticles, demonstrating a proportionality between DT and composition. Furthermore, composition distributions can be determined since measured DT values vary as a function of retention time. The correlation of DT-derived cumulative distribution plots with TEM-EDS results confirmed the compositional polydispersity within hybrid nanoparticle populations. This composition-based fractionation of multicomponent inorganic nanoparticles provides insights into the fundamental forces governing thermal diffusion and highlights the ability of this technique for complex nanoparticle separations and analyses.
All Science Journal Classification (ASJC) codes
- Materials Science(all)