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Dispersion polymerization of acrylamide (PAM) has been successfully carried out in aqueous ammonium sulfate media by using poly(acryloyloxyethyl trimethylammonium chloride) (PAOTAC) as the polymeric stabilizer and 2,2Ј-azobis(2-methyl propionamidine) dihydrochloride (AIBA) as the initiator. The polymerization behaviors with varying concentrations of acrylamide, PAOTAC, AIBA, and ammonium sulfate were investigated. The reaction conditions for stable dispersion were concentrations of 5-10% for acrylamide, 0.6 -1.8% for the stabilizer, 0.92-1.84 ϫ 10 Ϫ4 mol/L for the initiator, and 24 -30% for the salt. The resulting conversion-time curves were Sshaped, as is typically observed in polymerization. Polydisperse spherical particles were formed in the system. An image analyzer photographed the size of the dispersed particles and their distribution was measured. The mechanism and kinetics for the dispersion polymerization were discussed.

ABSTRACT:Copolymer particles consisting of acrylamide (AM) and acryloyloxyethyl dimethylbenzyl ammonium chloride (AODBAC) were prepared by dispersion polymerization in an aqueous solution of ammonium sulfate and in the presence of poly(acryloyloxyethyl trimethyl ammonium chloride) (PAOTAC) as the stabilizer. The average particle size ranged from 4 to 7 m, and M w and M n were 2-6 ϫ10 6 g/mol and 1-3 ϫ 10 6 g/mol, respectively. The effects of the AM/AODBAC ratio, monomer, initiator, salt, and stabilizer concentration on the particle size and molecular weight were studied. Increase of the AODBAC/AM ratio resulted in a decrease in the molecular weight and an increase in particle size. With the increase of the AODABA/AM ratio, the dispersion became less stable during long storage. Due to the presence of the salt, ionization of the quaternary ammonium groups in the dispersed particles is considered significantly suppressed.

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