PNIPAAM grafted particle monoliths: parameters affecting structure and morphology

Abstract

Crosslinked polystyrene latex particles generated with surfactant free emulsion polymerization were functionalized with thin layer of ATRP initiator on the surface. The functionalized particles were aggregated as physical networks using high shear techniques. The latex particles as well as the aggregated particles were used to successfully generate thermo-responsive monoliths by grafting PNIPAAM brushes from the surface of the particles by atom transfer radical polymerization and simultaneous crosslinking of these brushes. Different solid fractions and drying conditions were used in the generation of the monoliths and the effect of these variations on the structure and morphology of the monoliths was analyzed. Surprising morphologies consisting of tubes or channels were observed when higher solid fractions were used. This behavior was enhanced when the monoliths were dried at higher temperatures. By using proper solid fractions and drying conditions, homogenous porous monoliths could be achieved.