Precipitation−Redispersion of Cerium Oxide Nanoparticles with Poly(acrylic acid):  Toward Stable Dispersions

Abstract

We exploit a precipitation-redispersion mechanism for complexation of short chain polyelectrolytes with cerium oxide nanoparticles to extend their stability ranges. As synthesized, cerium oxide sols at pH 1.4 consist of monodisperse cationic nanocrystalline particles having a hydrodynamic diameter of 10 nm and a molecular weight 400000 g·mol -1 . We show that short chain uncharged poly(acrylic acid) at low pH when added to a cerium oxide sols leads to macroscopic precipitation. As the pH is increased, the solution spontaneously redisperses into a clear solution of single particles with an anionic poly(acrylic acid) corona. The structure and dynamics of cerium oxide nanosols and their hybrid polymer-inorganic complexes in solution are investigated by static and dynamic light scattering, X-ray scattering, and by chemical analysis. Quantitative analysis of the redispersed sol gives rise to an estimate of 40 -50 polymer chains per particle for stable suspension. This amount represents 20 % of the mass of the polymer-nanoparticle complexes. This complexation adds utility to the otherwise unstable cerium oxide dispersions by extending the range of stability of the sols in terms of pH, ionic strength and concentration.

Polydimethylsiloxane (PDMS) Coating onto Magnetic Nanoparticles Induced by Attractive Electrostatic Interaction

“…This coating was well described in previous articles, and gave a good stability to nanoparticles [22,23]. Its thickness was estimated by light scattering, comparing the hydrodynamic diameters from bare and coated nanoparticles (Table 1).…”

“…In order to improve their colloidal stability at neutral pH in water and to control their association with the PDMS-based copolymer, magnetic nanoparticles are coated with oppositely charged polyelectrolyte, namely polyacrylic acid with a molecular weight of 2,100 g·mol −1 (Sigma Aldrich). This synthesis followed the precipitation redispersion process described previously [22]. The precipitation of the cationic γ-Fe 2 O 3 dispersion by PAA2K was performed by mixing the acidic solution of PAA2K (1 wt.%) and the acidic nanoparticle dispersion (1 wt.%) at a 2:1 weight ratio (excess of polymer).…”

“…First, polyacrylic acid polymer (2,100 g/mol, noted PAA2k) is selected to stabilize iron oxide nanoparticles in water [22,23] at pH from 4 to 11. We already demonstrated that this coating provides both stability and post functionalization to prepare controlled aggregates, either spherical [24] or elongated [25,26].…”

Stability and Adsorption Properties of Electrostatic Complexes: Design of Hybrid Nanostructures for Coating Applications

“…For SDS micelles, the structural charge was assimilated to the aggregation number, yielding a charge of -50e, where e denotes the elementary charge. For the PAA2K-coated cerium particles, we have estimated the structural charge of -700e, assuming that 50 % of the 50 PAA2K (per particle) were actually adsorbed at the cerium oxide interface [12]. Static and dynamic light scattering was used to investigate the microstructure and stability of the electrostatic complexes in bulk solutions.…”

Nanoceria and Its Perspective in Cancer Treatment

“…In order to improve the stability of the nanoceria dextran could play a major role which was observed by Perez et al They have used cerium salt and dextran to make the dextran-coated nanoceria and different tests were performed like TEM, DLS, XRD, FTIR etc. to ensure the stability [50][51][52]. These functionalization surely help to minimize the toxic effects of the metallic nanoparticles like nanoceria and increase its efficacy.…”