A novel and controllable route for preparing high solid-content and low-viscosity poly(acrylamide-co-acrylic acid) aqueous latex dispersions

Abstract

High solid-content and low-viscosity poly(acrylamide-co-acrylic acid) aqueous latex dispersions have been successfully synthesized by copolymerization of acrylamide (AM) and acrylic acid (AA) in an aqueous solution of ammonium sulfate (AS) and lithium sulfate (LS) based on a distinctly novel strategy, the so called Swollen-Diffusion-In situ redox Polymerization (SDIP), which involves swelling followed by diffusion and redox initialized polymerization inside the seed particle, avoiding the high viscosity progress resulting from homogeneous nucleation in the continuous phase. Compared to the widely used one stage synthetic protocol, this process affords much more effective control over the viscosity of the dispersion and molecular weight of the resultant polymer by simply changing the concentration of inorganic salts and addition rate of the oxidant. The synthesized aqueous latex dispersions have been characterized using Fourier-transform infrared (FT-IR) spectroscopy, H nuclear magnetic resonance (¹HNMR) spectroscopy, and optical microscopy. The mechanism governing the formation of the latex dispersion is also extensively discussed.