The synthesis of water soluble cationic microgels by dispersion polymerization: Their performance in kaolin deposition onto fiber

The water soluble cationic microgels (CMG), intramolecularly cross-linked cationic polymers of acrylamide (Am) and diallyldimethylammonium chloride (DADMAC), were synthesized with dispersion polymerization in the mixture of tert-butanol (TBA)/water in the presence N, N0-methylene-bisacrylamide (MBA) as the cross-linker, poly(N-vinylpyrrolidone (PVP) as the stabilizer and 2, 20-azobisisobutyronitrile (AIBN) as the initiator. The effects of monomer, cross-linker, initiator, and stabilizer concentration on both particle size and molecular weight of CMG were investigated. The well dispersed polymer particles were produced in the range of poly dispersity index 1.1-1.4 and the molecular weight distribution with bimodal. Additionally, the efficiencies of two CMGs in the clay deposition on the bleached kraft fibers were investigated and compared with commercially widely used cationic polyacrylamide (CPAM) and poly-diallyldimethylammonium chloride (poly-DADMAC). The experiments showed that the CMGs were found as the effective flocculation agents and their efficiencies depended on their molecular weight and charge density.