Temperature controlled dispersion of poly(n-isopropyl acrylamide) treated silica clusters

The dispersion of particle agglomerates is affected by the presence of any chemical additives incorporated within the agglomerate structure. Traditional additives change the particle-particle and particle-matrix interactions to a degree that depends primarily on the chemical nature of the additive and its concentration within the agglomerate. A new generation of additives, based on polymeric systems that respond to external stimuli, allows the adjustment of interparticle interactions by manipulating the variable to which the additive is responsive. In this study, dispersion tests in simple shear flow are used to examine the effect of a thermally responsive additive, poly(N-isopropyl acrylamide) (PNIPAM), on the dispersion behavior of silica agglomerates. The temperature sensitivity of the dispersion mechanisms and kinetics for silica clusters treated with either linear or crosslinked PNIPAM has been examined.