Synthesis of Acrylic Acid Copolymers by <scp>DL</scp>‐Methionine–Mediated <scp>RDRP</scp> and Their Dispersion Behavior to Pigment Red 122 in Water

ABSTRACT Dispersants play a pivotal role in the formulation of water‐based ink pastes, where their incorporation results in the formation of smaller nano‐scale pigment particles, a reduction in color paste viscosity, and an enhancement in stability, thereby facilitating the production of water‐based ink. A series of copolymers of acrylic acid (AA) and 2‐ethylhexyl acrylate (2‐EHA) with different molar ratios and different polymer structures are successfully synthesized by DL‐methionine mediated reversible deactivation radical polymerization (RDRP). Additionally, terpolymers with different functional side groups are further successfully synthesized. The capacity of these copolymers to disperse pigment red 122 (P.R.122) in water as dispersants is evaluated. Research indicates that when the mole ratio of AA to 2‐EHA is 20:1, poly(acrylic acid‐ ran ‐2‐ethylhexyl acrylate) (AA‐ ran ‐2‐EHA) exhibits the strongest dispersion capability to P.R.122, and the average particle size of P.R.122 paste is 227.52 nm, D90 is 275.31 nm, the viscosity is 21.33 mPa s, the Zeta potential is −69.67 mV, and the P.R.122 color paste is stably stored at 60°C for 7 h. The introduction of the third monomers, 2‐hydroxypropyl acrylate (HPA), and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS), can further improve the dispersion performance of the copolymer for P.R.122 paste.