The present invention relates to a copolymer which is obviously by polymerizing monomer components comprising: (a) a compound represented by formula (A1): Y—B-0-(A-0)mR2(A1) wherein Y represents an alkenyl group containing two or more carbon atoms, B represents a C2-18 oxyalkylene group; R2 represents a hydrogen atom or a C1-30 hydrocarbon group and m represents an integer of from 0 to 300; and/or an addition product obtained by the addition of 0-8 moles of any alkylene oxide having 2 to 4 carbon atoms to one equivalent of amino residues in polyamide polyamine obtained by condensation of 1.0 moles of apolyalkylene polyamine, 0.8-0.95 mole of a dibasic acid or an ester of the dibasic acid with a lower alcohol having 1 to 4 carbon atoms, and 0.05-0.18 mole of acrylic acid or methacrylic acid, or an ester of acrylic acid or methacrylic acid with a lower alcohol having 1 to 4 carbon atoms; (b) an unsaturated monocarboxylic acid or a salt thereof, or an unsaturated dicarboxylic carboxylic acid or a salt thereof or an anyhydride of an unsaturated cicarboxylic acid; and (c) a compound represent by formula (C): R11R12C═CR13—(CR3R4)n—O—CO—CH═CH—COOR16(C) wherein R3 and R4 independently from each other are hydrogen or an alkyl group, wherein one of R11, R12 and R13 is methyl and the other two groups are hydrogen or wherein all of R11, R12 and R13 are hydrogen, wherein R16 is hydrogen, an alkaline metal atom, an earth alkaline metal atom, ammonium or an organic ammonium group and wherein n is 1 or 2 and to a dispersant inorganic binders (such as cement) comprising said copolymer; and, when m is 0, esterifying the resulting copolymer with a compound of formula HO-(A-O—)2R2, wherein R2 represents a hydrogen atom or a C1-30 hydrocarbon group and z represents an integer of from 1 to 300.