PH-triggered dispersion of nanoparticle clusters

Nanoparticle cluster dispersion into a stable colloidal suspension at a rate dependent upon pH was analyzed by using an UV/Visible spectrophotometer. A poly(N-vinylformamide) PNVF shell was formed on silica nanoparticles by crosslinking PNVF using a novel crosslinker, 2-bis[2,2'-di(N-vinylformamido)ethoxy] propane (BDEP), containing an acid-labile ketal. Monodisperse spherical silica particles, prepared by Stober method with an average diameter of 160 nm were used as templates for the synthesis of PNVF shell/silica-core particles, 3-Methacryloxypropyltrimethoxysilane (MPS) was attached to the silica surface by subsequent addition of MPS into the Stober reaction mixture after the silica particles were formed. MPS-silica nanoparticles were then coated with PNVF, which was subsequently crosslinked by BDEP to create the shell serving as the interparticle barrier within the nanoparticle clusters.