title: Direct Probing of Dispersion Quality of ZrO2 Nanoparticles Coated by Polyelectrolyte at Different Concentrated Suspensions.
abstract: This study reports useful application of the electrokinetic sonic amplitude (ESA) technique in combination with rheometry and electron microscopy techniques for direct probing the stability of low and high-concentrated zirconia (ZrO2) nanosuspensions in the presence of an alkali-free anionic polyelectrolyte dispersant Dolapix CE64. A comparative study of the electrokinetic characteristics and the rheological behavior of concentrated ZrO2 nanosuspensions has been done. Good agreement was obtained from relationship between the electrokinetic characteristics (zeta potential, ESA signal), viscosity, and its pH dependence for each concentrated ZrO2 nanosuspension with different dispersant concentration in the range of 0.9-1.5 mass%. A nanoscale colloidal hypothesis is proposed to illustrate that the addition of different amounts of dispersant influences on both the stability and the electrokinetic and rheological properties of concentrated ZrO2 nanosuspensions. It is found that an optimum amount of 1.4 mass% dispersant at the inherent pH (>9.2) can be attached fully onto the nanoparticles with sufficient electrosteric dispersion effects, suitable for casting applications. Supplementary scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) analyses followed by colorization effect were taken to verify the visible interaction between dispersant and nanoparticles surfaces. SEM and HR-TEM images proved the existence of visible coverage of dispersant on the surface of individual nanoparticles and showed that thin polyelectrolyte layers were physically bound onto the particles' surfaces. This study will be of interest to materials scientists and engineers who are dealing with dispersion technology, nanoparticle surface treatments, functionalization, characterization, and application of bio/nanoparticle suspensions at various concentrations using different types of polymers.
authors.affiliation: State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing, 210016, China. hsarraf@wgu.edu.|Western Governors University, 1001 Fourth Avenue, Seattle, WA, 98154-1101, USA. hsarraf@wgu.edu.|NANOPRODEX LLC, NW, 48th Ave, Vancouver, WA, 98685, USA. hsarraf@wgu.edu.
authors.forename: Hamid
authors.initials: H
authors.lastname: Sarraf
authors.affiliation: State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing, 210016, China. qianzh@nuaa.edu.cn.
authors.forename: Zhenghua
authors.initials: Z
authors.lastname: Qian
authors.affiliation: University of Chemistry and Technology, 166 28, Prague, Czech Republic.
authors.forename: Ludmila
authors.initials: L
authors.lastname: Škarpová
authors.affiliation: State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing, 210016, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.affiliation: Institute of Electronic and Sensor Materials, TU Bergakademie Freiberg, Gustav-Zeeunter-Str. 3, Freiberg, 09596, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Herbig
authors.affiliation: University of Chemistry and Technology, 166 28, Prague, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Maryška
authors.affiliation: University of Chemistry and Technology, 166 28, Prague, Czech Republic.
authors.forename: Lidmila
authors.initials: L
authors.lastname: Bartovska
authors.affiliation: University of Chemistry and Technology, 166 28, Prague, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Havrda
authors.affiliation: Department of Bioengineering, 900 University Ave., University of California, Riverside, CA, 92521, USA.
authors.forename: Bahman
authors.initials: B
authors.lastname: Anvari
keywords: Anionic polyelectrolyte dispersant DOLAPIX CE64; Colloidal dispersion; Electrokinetic sonic amplitude (ESA) technique; SEM; TEM; Viscosity; Zeta-potential; ZrO2 nanoparticle