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

Abstract

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 in 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 blending the 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 acidcoated 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 Published in ACS Applied Nano Materials (2018) 2 damage but provides a better barrier to water. This work shows how the nanoparticle chemical functionalization can be used to manipulate the structure and to tailor the properties of UV-absorbing barrier coatings.

Surface Modification Design for Improving the Strength and Water Vapor Permeability of Waterborne Polymer/SiO2 Composites: Molecular Simulation and Experimental Analyses

“…There are more KH550-SiO2 and 560-SiO2 particles are on the surface of latex particles, this is mainly because that stronger hydrogen bonds or electrostatic interactions is formed between modified-SiO2 nanoparticles and latex particles, compared with SiO2 nanoparticles. KH570-SiO2 nanoparticles which enter the interior of PMA latex particles seem less clear (Figure 9e), and other nanoparticles appear on the latex particle surface as black phase [46]. Different surface modification between the above four SiO2 sources explains the difference in the distribution of SiO2 nanoparticles.…”

Colloidal assembly of polydisperse particle blends during drying

“…Such flow will affect nanoparticles in a stronger way, as they can be transported through closed packed arrays of larger particles. 33,34 As a result, the edge of the final dried film will present a larger content of small particles than its centre. If the evaporation rate is fast, then the nanoparticles are more likely to get trapped at the fast moving air/water interface reducing their lateral flow to the edge, 35 and the drying time will be significantly reduced, minimizing the time for the particles to move to the edges.…”

Nanocomposites of Au/Disentangled UHMWPE: A Combined Optical and Structural Study

“…The VIS/NIR absorption spectra of composites characterized by different draw ratios are presented in Figure 4. To normalize the results by sample thickness, the linear absorption coefficient, µ, is employed as presented in Equation (1) [34]:…”