Study on the dispersion mechanism of the polycarboxylic acid dispersant for disperse dyes

•The dispersion mechanism was investigated by molecular dynamics simulations.•The carboxylate groups of the dispersant make the dyes repel each other.•The hydrophobic styrene residues make the dispersants adsorb to the dye surfaces.•The branched chains make the dispersants combine with the dye crystals better.•The experimental results verified the correctness of the simulation results.