Details

Autor(en) / Beteiligte

• Rudolph, Martin
• Peuker, Urs A.

Titel

Coagulation and stabilization of sterically functionalized magnetite nanoparticles in an organic solvent with different technical polymers

Ist Teil von

• Journal of colloid and interface science, 2011-05, Vol.357 (2), p.292-299

Ort / Verlag

Amsterdam: Elsevier Inc

Erscheinungsjahr

2011

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Polymers in an organic solvent based nanoparticle dispersion can cause coagulation or stabilization through depletion interactions and adsorption effects which is important for polymer composite synthesis influencing primary particle concentration. [Display omitted] ► Thermo gravimetric analyses can quantify the content of primary particles. ► PVB adsorbs and stabilizes magnetite nanoparticle dispersions in organic solvents. ► PC has a stronger destabilization effect compared to PMMA for same coil sizes. ► Primary particle concentration decreases with increasing polymer concentration. ► Extinction and DLS analyses reveal formation of larger structures by PVB adsorption. This experimental study deals with the colloidal stability of sterically functionalized magnetite nanoparticles in a low dielectric constant organic solvent with different concentrations of technical grade polymers. Those dispersions are the starting point of a solution and spray drying process chain to synthesize highly filled nanocomposite materials with nanoparticle volume concentrations exceeding 10%. We introduce a thermo gravimetric method together with light extinction and dynamic light scattering measurements to gain quantitative information on the concentration of primary particles and the mechanism of destabilization or stabilization by polymer addition. Poly(vinyl butyral) is found to stabilize the dispersion considerably caused by stronger interactions with the fatty acid coated magnetite particles quantified by means of adsorption measurements. Both poly(methyl methacrylate) as well as two grades of poly(bisphenol A carbonate) are found to destabilize the dispersion due to depletion flocculation over the entire concentration range investigated However there is a significant quantity of a stable fraction of primary nanoparticles in the supernatant after depletion flocculation occurred. This fraction of primary particles is increasing with decreasing polymer concentration. We furthermore point out important concerns and limitations for the composition of and concentrations in such complex colloidal systems for use in industrially relevant processes.