Core–Shell Structure of Monodisperse Poly(ethylene glycol)-Grafted Iron Oxide Nanoparticles Studied by Small-Angle X-ray Scattering

Abstract

The promising applications of core–shell nanoparticles in the biological and medical field have been well investigated in recent years. One remaining challenge is the characterization of the structure of the hydrated polymer shell. Here we use small-angle X-ray scattering (SAXS) to investigate iron oxide core–poly(ethylene glycol) brush shell nanoparticles with extremely high polymer grafting density. It is shown that the shell density profile can be described by a scaling model that takes into account the locally very high grafting density near the core. A good fit to a constant density region followed by a star-polymer-like, monotonously decaying density profile is shown, which could help explain the unique colloidal properties of such densely grafted core–shell nanoparticles. SAXS experiments probing the thermally induced dehydration of the shell and the response to dilution confirmed that the observed features are associated with the brush and not attributed to structure factors from particle aggregates. We thereby demonstrate that the structure of monodisperse core–shell nanoparticles with dense solvated shells can be well studied with SAXS and that different density models can be distinguished from each other.

Towards Multi-Functional SiO2@YAG:Ce Core–Shell Optical Nanoparticles for Solid State Lighting Applications

“…On the other hand, the coating process resulted in the formation of a YAG:Ce shell, growing on the SiO 2 particle surface gradationally by heterogeneous nucleation. Similar side maximum or shoulders have been reported in the literature as particle−particle interactions (structure factor) [40][41][42][43]. In SiO 2 @YAG:Ce with two times coating (coat II), the progressive growth of shell is more visible in the SAXS in which the shoulder or specific side maximum is more clear (Figure 7b), suggesting that the shell grows with time.…”

Preparation and characterization of Ag–Pd bimetallic nano-catalysts in thermosensitive microgel nano-reactor

“…SAXS is especially capable of analyzing the sample in a mild condition where is almost no destruction for samples. [29][30][31][32] Moreover, SAXS could give a detailed illustration of spatial distribution of the metal nanoparticles.…”

Al and PEG Effect on Structural and Physicochemical Properties of CoFe2O4

“…In particular, the CoFe 2 O 4 has covered a broad applications including electronic devices, ferrofluids, magnetic drug delivery, microwave devices and high density information storage. [4][5][6][7][8][9] Cobalt ferrite (CoFe 2 O 4 ) is one of the well known hard magnetic materials which has strong magnetic anisotropy, high magnetostriction, moderate magnetization, high coercivity at room temperature and high chemical stability and good electrical insulation. [10][11][12][13] There are different methods which have been reported for the preparation of magnetic nanoparticles of cobalt ferrite.…”