Preparation and Characterization of Amphoteric Poly(acrylamide-itaconic acid-diallyl dimethyl ammonium chloride) Uniform Spherical Particles by Aqueous Dispersion Polymerization

Abstract

Amphoteric polyacrylamide (AmPAM) spherical particles dispersed uniformly in ammonium sulfate (AS) aqueous solution with long-time stability was prepared using acrylamide (AM), itaconic acid (IA) and diallyl dimethyl ammonium chloride (DMDAAC) as monomers, 2,2′-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride (VA-044) as initiator and poly(diallyl dimethyl ammonium chloride) (PDMDAAC) as stabilizer by the ways of aqueous dispersion polymerization. The effects of PDMDAAC, ammonium sulfate and monomer concentration on the morphology of the dispersed spherical particles were investigated. The particle size yields little swell when the AS concentration is only in the range from 15% to 16% (based on the total solution), then the particle size is not an obvious variation at AS concentration above 16%. The particles size increased firstly, then decreased with the increase of stabilizer concentration in the range of 12–28%. There is an increasing trend in the particle size with increasing the concentration of monomer. The effects of the main reaction parameters, such as the pH value, the concentrations of ammonium sulfate, PDMDAAC, monomers and VA-044, on the molecular weight and the stability of the dispersion were also studied. The results indicate that the apparent viscosity is the lowest at the pH value of about 7. When the range of the AS concentration was 15–17%, the dispersion system shows good fluidity and stability. At the concentration of AS above 17%, apparent viscosity increased rapidly. The stabilizer and monomers concentration affect stability of the dispersion system, respectively. The apparent viscosity increased with an increase of the PDMDAAC and monomers concentration. The average molecular weight of AmPAM increased firstly and then decreased with an increase of the initiator concentration. That is, the suitable reaction conditions for obtaining stable amphoteric polyacrylamide dispersion system are as following: concentrations of 15–17% for ammonium sulfate, 12–20% for PDMDAAC, 5–7% for monomers and 200–600 mg kg−1 for VA-044.