Compaction of TiO 2 suspension by using dual ionic thermosensitive polymers

Abstract

The compaction of TiO 2 suspension as a negatively charged model suspension by using dual ionic thermosensitive polymers was investigated. First, a cationic thermosensitive polymer, poly ( N-isopropylacrylamide- co- N, N-dimethylaminopropylacrylamide) was added to the TiO 2 suspension, followed by an anionic thermosensitive polymer, poly ( N-isopropyl-acrylamide- co-acrylic acid). By adding the latter, a polymer complex with the cationic thermosensitive polymer adsorbed on the particle is formed, and charge neutralization occurs to decrease the transition temperature of the polymer adsorbed on the TiO 2 particles. As a result, the compaction of the TiO 2 suspended particles due to the hydrophobic interaction of the adsorbed polymers occurs at a relatively low temperature by applying an adequate mechanical force with a plunger. In order to initiate the compaction, it was necessary to cover the surface of the TiO 2 particles sufficiently by the cationic thermosensitive polymer molecules, and the optimum dosage of the anionic thermosensitive polymer was observed. The transition temperature of the polymer complex adsorbed on the TiO 2 particles was dependent on the ratio of the dosages of the cationic and anionic thermosensitive polymers.