A reactive core-shell nanoparticle approach to prepare hybrid nanocomposites: Effects of processing variables

Reactive core-shell nanoparticles are prepared in aqueous media by the addition of a solution of an amphiphilic organic polymer and a metal oxide precursor. The nanoparticles are thought to form by nucleation, with a core-shell structure forming later. Using acid catalysis the precursor is converted to metal oxide by an in situ sol-gel reaction. The hybrid nanoparticles, prepared with 10, 15, and 20 wt% Al(OiPr)3, are dried and compression moulded, yielding flexible, transparent films (0.5 and 2 mm) that retain a core-shell nanoparticle structure and show well-distributed alumina-rich domains throughout the organic matrix. Preliminary results are given that show relationships between processing variables and film properties (particle diameter, appearance of the core, Tg (glass transition temperature), and storage modulus). The apparent stability of the alumina distribution is also discussed. Nanoparticles prepared using 10 wt% Al(OiPr)3 (aluminium isopropoxide) gave films that, depending on the nanoparticles\u27 process conditions, possessed core-shell nanoparticles with a median diameter of 45 ± 2 nm and a Tg that was 27 °C above the matrix polymer\u27s Tg, or a median nanoparticle diameter of 161 ± 30 nm and a Tg that was 17 °C above the matrix polymer\u27s Tg. © 2005 IOP Publishing Ltd