Pigment based inks including: a non-polar carrier fluid; and a surface-functionalized pigment particle, wherein the particle has had attached to the surface thereof a graft co-polymer via azide chemistry, wherein the graft copolymer, before attachment to the surface, has a formula selected from the group consisting of graft copolymer 1, graft copolymer 2, and graft copolymer 3, as shown below: wherein, L 1, L 2, and L 3 are each independently a chemical structure selected from the group consisting of C-C, C=C, C=N; SG 1 and SG 2 each independently represent a solublizing and sterically bulky group, which helps to improve the solubility of the polymer and stabilize the colorant particles, selected from the group consisting of alkyl groups, alkoxy groups, branched alkyl groups, branched alkoxy groups, aliphatic esters, branched aliphatic esters, substituted phenyl groups, and macromolecular monomers; FG represents a functional group that provides charging sites to pigment surfaces, selected from acidic functional groups and basic groups; x, y, and z are each independently an integer between 1 and about 5,000; n is an integer between 1 and about 100; and a is an integer between 0 and about 5,000, while b is an integer between 2 and about 5,000, and after attachment to the surface, the graft co-polymer is nitrogen-linked to the surface of the pigment particle. a non-polar carrier fluid; and a surface-functionalized pigment particle, wherein the particle has had attached to the surface thereof a graft co-polymer via azide chemistry, wherein the graft copolymer, before attachment to the surface, has a formula selected from the group consisting of graft copolymer 1, graft copolymer 2, and graft copolymer 3, as shown below: wherein, L 1, L 2, and L 3 are each independently a chemical structure selected from the group consisting of C-C, C=C, C=N; SG 1 and SG 2 each independently represent a solublizing and sterically bulky group, which helps to improve the solubility of the polymer and stabilize the colorant particles, selected from the group consisting of alkyl groups, alkoxy groups, branched alkyl groups, branched alkoxy groups, aliphatic esters, branched aliphatic esters, substituted phenyl groups, and macromolecular monomers; FG represents a functional group that provides charging sites to pigment surfaces, selected from acidic functional groups and basic groups; x, y, and z are each independently an integer between 1 and about 5,000; n is an integer between 1 and about 100; and a is an integer between 0 and about 5,000, while b is an integer between 2 and about 5,000, L 1, L 2, and L 3 are each independently a chemical structure selected from the group consisting of C-C, C=C, C=N; SG 1 and SG 2 each independently represent a solublizing and sterically bulky group, which helps to improve the solubility of the polymer and stabilize the colorant particles, selected from the group consisting of alkyl groups, alkoxy groups, branched alkyl groups, branched alkoxy groups, aliphatic esters, branched aliphatic esters, substituted phenyl groups, and macromolecular monomers; FG represents a functional group that provides charging sites to pigment surfaces, selected from acidic functional groups and basic groups; x, y, and z are each independently an integer between 1 and about 5,000; n is an integer between 1 and about 100; and a is an integer between 0 and about 5,000, while b is an integer between 2 and about 5,000,