To modify the surface of organic pigments such as 5,12-dihydoroquino[2,3-beta]acridine-7,14-dione (quinacridone, QD), 3,6-di(p-chlors ophenyl)-1,4-diketo-pyrrolo[3,4-c]pyrrole (diketo-pyrrolopyrrole: DPP), and 1,1'-bi(9,10-anthracene-dione)-4,4'-diamine (anthraquinone: AQ), the grafting of polymers with these organic pigments at the amino groups was investigated. The amino groups of QD, DPP, and AQ readily reacted with living poly(isobutyl vinyl ether) (poly(IBVE)) cation with controlled molecular weight and narrow molecular weight distribution. Grafting of living poly(2-methyl-2-oxazoline) (poly(MeOZO)) cation onto these organic pigments was also performed. The mole number of the grafted polymer chain on the organic pigment surface decreased with increasing molecular weight of the living polymer, because the steric hindrance of the organic pigment surface increased with increasing molecular weight of living polymer. By rafting of poly(IBVE) onto the QD surface, the wettability of the surface drastically changed from hydrophilic to hydrophobic. (C) 1997 Elsevier Science S.A.