Preparation of Novel Core‐Shell Nanocomposite Particles by Controlled Polymer Bridging

Abstract

Ceramics that are composed of nanosized granules show enhanced properties in various applications. A layer‐by‐layer deposition process is developed in this study to prepare core—shell nanocomposite particles, using controlled polymer adsorption. Submicrometer‐sized alumina particles that have been chosen as the starting core particles are first dispersed by pH control and then modified by adsorption of anionic poly(acrylic acid) to facilitate the subsequent deposition of nanoparticles on them. A key step in the processing involves the removal of excess polymer in the supernatant after the adsorption by controlled washing, so that the added nanoparticles do not self‐flocculate among themselves. A coating of nanosized particles is indicated by the charge reversal of the micrometer‐sized composite particles. The isoelectric point of the composite particle is similar to that of nanosized particles under both low and high coverage conditions. Scanning electron microscopic observation of coated particles shows full monolayer coverage of the nanoparticles on core particles, which confirms the efficiency of the coating scheme that is discussed here. The present study reveals the feasibility of coating nanoparticles onto micrometer‐sized core particles, using controlled polymer bridging, for the preparation of the multilayer nanocomposite powders.