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Aqueous latex/ceramic nanoparticle dispersions: colloidal stability and coating properties
Jiakuan Sun1, Bhaskar V Velamakanni, William W Gerberich
1Department of Chemical Engineering and Materials Science, University of Minnesota, 151 Amundson Hall, 421 Washington Avenue SE, Minneapolis, MN 55455, USA.
Journal of Colloid and Interface Science
|November 10, 2004
Summary
Dispersion pH significantly impacts the colloidal stability of antimony-doped tin oxide (ATO) or indium tin oxide (ITO) nanoparticles with poly(vinyl acetate-acrylic) copolymer (PVAc-co-acrylic) latex. Optimal pH control is crucial for stable dispersions and high-performance composite coatings.
Area of Science:
- Materials Science
- Colloid and Surface Chemistry
- Nanotechnology
Background:
- Colloidal stability of nanoparticle dispersions is critical for developing advanced composite materials.
- Understanding the influence of pH on nanoparticle-copolymer interactions is essential for controlling dispersion properties.
- Antimony-doped tin oxide (ATO) and indium tin oxide (ITO) nanoparticles are widely used in electronic and optical applications.
Purpose of the Study:
- To investigate the effect of pH on the colloidal stability of ATO and ITO nanoparticle dispersions with PVAc-co-acrylic latex.
- To correlate dispersion stability with the microstructure, electrical, and optical properties of resulting composite coatings.
- To validate experimental findings using Derjaguin, Landau, Verwey and Overbeek (DLVO) theory.
Main Methods:
- Zeta potential measurements to determine the isoelectric points (IEPs) of ATO, ITO, and PVAc-co-acrylic latex.
- Preparation and observation of dispersion stability at various pH values.
- Application of DLVO theory to predict interparticle interactions.
- Characterization of composite coatings' microstructure, electrical, and optical properties.
Main Results:
- ATO nanoparticles have an IEP below pH 2.0; PVAc-co-acrylic latex has an IEP around pH 2.0. Stable ATO/PVAc-co-acrylic dispersions were achieved at pH 3.0, while aggregation occurred at pH 1.5.
- ITO nanoparticles have an IEP around pH 6.0. Stable ITO/PVAc-co-acrylic dispersions were obtained at pH 3.0 and 11.0, with instability at pH 6.0.
- DLVO theory predictions aligned with experimental observations regarding dispersion stability and particle interactions.
- Coatings derived from aggregated suspensions exhibited lower percolation thresholds and transparencies compared to those from stable dispersions.
Conclusions:
- Dispersion pH is a critical factor controlling the colloidal stability of ATO/PVAc-co-acrylic and ITO/PVAc-co-acrylic systems.
- Achieving stable dispersions through pH control is essential for optimizing the performance of ATO/ITO-based composite coatings.
- The findings provide valuable insights for the formulation and processing of functional nanocomposite materials.