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Design of Waterborne Nanoceria/Polymer Nanocomposite UV-Absorbing Coatings: Pickering versus Blended Particles

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journal contribution
posted on 18.07.2018, 00:00 by Ignacio Martín-Fabiani, Ming Liang Koh, Florent Dalmas, Katrin L. Elidottir, Steven J. Hinder, Izabela Jurewicz, Muriel Lansalot, Elodie Bourgeat-Lami, Joseph L. Keddie
Nanoparticles of cerium dioxide (or nanoceria) are of interest because of their oxygen buffering, photocatalytic ability, and high UV absorption. For applications, the nanoceria can be incorporated into a polymer binder, but questions remain about the link between the nanoparticle distribution and the resulting nanocomposite properties. Here, the thermal, mechanical, and optical properties of polymer/ceria nanocomposites are correlated with their nanostructures. Specifically, nanocomposites made from waterborne Pickering particles with nanoceria shells are compared to nanocomposites made from the blending of equivalent surfactant-free copolymer particles with nanoceria. Two types of nanoceria (protonated or citric acid-coated) are compared in the Pickering particles. A higher surface coverage is obtained with the protonated ceria, which results in a distinct cellular structure with nanoceria walls within the nanocomposite. In the blend of particles, a strong attraction between the protonated nanoceria and the acrylic acid groups of the copolymer likewise leads to a cellular structure. This structure offers transparency in the visible region combined with strong UV absorption, which is desired for UV-blocking coating applications. Not having an attraction to the polymer, the citric acid-coated nanoceria forms agglomerates that lead to undesirable light scattering in the nanocomposite and yellowing. This latter type of nanocomposite coating is less effective in protecting substrates from UV damage but provides a better barrier to water. This work shows how nanoparticle chemical functionalization can be used to manipulate the structure and to tailor the properties of UV-absorbing barrier coatings.

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