Clustering of asymmetric dumbbell-shaped silica/polystyrene nanoparticles by solvent-induced self-assembly

Abstract

We report a quite simple strategy to assemble silica/polystyrene dumbbell-shaped nanoparticles into clusters with an aggregation number from two to more than 30. The polystyrene lobe serves as a patch that is made sticky and ready to merge with similar ones when the dumbbells are dispersed in an ethanol/DMF mixture. Thanks to transmission electron microscopy experiments, we describe qualitatively and quantitatively the influence of several experimental parameters such as the solvent quality, i.e. DMF fraction, and the patch-to-particle size ratio. We show that the DMF fraction range (30-50 vol. %) for the sticky regime can be extended if the incubation process is completed by a centrifugation step. We also demonstrate an unexpected evolution in the average aggregation number with the patch-to-particle size ratio that may be explained by the molar mass distribution within the polystyrene core of the clusters. Lastly, we show that this assembly route may be extended to gold-coated clusters.

Evidence of Structural Inhomogeneities in Hard-Soft Dimeric Particles without Attractive Interactions

“…The emerging picture is compatible with a fluid structure which progressively rearranges from homogeneous to cluster fluid upon lowering the temperature, even if no attraction in the intermolecular interaction is set. This behavior qualitatively agrees with experimental results on hard-soft dimers [40][41][42] where clusters are formed by partially overlapping the soft spheres of different dimers. We will further discuss on the agreement between our model and experimental data later on.…”

“…The cross correlations are also modeled by the Hertzian potential, in which the degree of softness is lower. The onset of aggregates in hard-soft dimeric particles has been already experimentally observed [40][41][42] even if in the experiments a neat attraction between the soft monomers was present. Here we investigate the formation of aggregates by using Monte Carlo (MC) simulations and integral equation theories of molecular liquids.…”

Colloidal molecules and patchy particles: complementary concepts, synthesis and self-assembly

“…130 They obtained quite regular submillimetre-sized clusters with aggregation numbers up to eight. Lastly, we recently reported the fabrication of clusters by using silica/PS asymmetric dumbbell-like nanoparticles (Figure 24), 131 synthesized…”

Dimpled SiO2@γ-Fe2O3 nanocomposites – fabrication and use for arsenic adsorption in aqueous medium

“…7,8,[24][25][26][27] However, we also managed to obtain a regrowth stage for gold by using Au NP seeds, in somewhat different approaches. 6,28 Nanocomposites containing plasmonic satellite elements, such as gold, can nd applications as photonic materials, superlenses and sensors or in life sciences, optics and coating industry. 7 The nanocomposites of the present work were employed for As removal in water as described below.…”