Nanoparticle Assemblies as Probes for Self-Assembled Monolayer Characterization: Correlation between Surface Functionalization and Agglomeration Behavior

Abstract

The ordering of dodecyl chains has been investigated in mixed monolayers of phosphonic acid capping agents on the surface of hydrothermally prepared zirconia nanocrystals. Methyl-, phenyl-, pyryl-, and tert-butylphosphonic acids have been used to investigate series with different mixing ratios with dodecylphosphonic acid as the cocapping agent for the mixed monolayer formation. Fourier transform infrared (FTIR) studies revealed that an increasing amount (different for each type) of coadsorbed capping agent reduces the ordering of the dodecyl chains significantly. Small-angle X-ray scattering (SAXS) verified that with increasing amount of cocapping agent the agglomeration of the particles decreases. The strong correlation of the agglomeration behavior with the ordering of the surface-bound alkyl chains leads to the conclusion that interparticle bilayers, formed via long alkyl chain packing, are responsible and can be controlled on a molecular level by coadsorbing various molecules. On the basis of this correlation, nanoparticles can be used as probes for self-assembled monolayer investigation by an indirect structural method (SAXS) and correlated with the routine spectroscopical method for the chemical analysis of surface groups (FTIR).

Tuning the Pore Size in Ionic Nanoparticle Networks

“…SAXS investigations could allow verifying the presence of nonagglomerated nanoparticles within the INN materials, as also discussed in the works of Feichtenschlager et al and Pabisch et al [26,27]. Indeed, differences in the scattering intensities can be observed corresponding to the typical size and distance of single nanoparticles present in the hybrid material, at about = 0.4 nm −1 for silica, 2 nm −1 for titania, and 1.0 nm −1 for zirconia (arrows on Figure 3).…”

“…Journal of Nanoparticles ( Figure 3) [26,27]. The macropores, larger than 20 nm, are formed in regions of the network where some ligands did not react.…”

Study of Perfluorophosphonic Acid Surface Modifications on Zinc Oxide Nanoparticles

“…Here, PFPDPA films created more agglomeration when compared to the other two modifications. Nanoparticles that were modified with long alkyl chains, as observed for PFPDPA, have been shown to increase the agglomeration as the order of the films increases [ 48 ]. The SEM images confirm that the morphologies of the nanoparticles do not change but the sizes of the particles increase after the surfaces are modified with the phosphonic acids.…”

Phosphonate-substituted zirconium oxo clusters

“…Many phosphonate-substituted zirconium compounds with 1D, layered 2D, and 3D interconnected structures have been reported [ 1 – 3 ], including coordination polymers with bis- or tetra-phosphonate ligands [ 4 – 11 ]. Surprisingly, no zirconium oxo clusters with phosphonate ligands are known, although zirconium oxo clusters with a variety of other bi- or multidentate ligands have been prepared and zirconia nanoparticles are frequently stabilized by phosphonate groups [ 12 , 13 ]. In this article, we report the preparation and structural characterization of the first phosphonate-substituted zirconium oxo clusters.…”