Plasticizers for aqueous suspensions of mineral particles and hydraulic binder pastes

A method for preparing a compound of following formula (I):

• where:
• n is an integer of between 1 and 100;
• i is an integer varying from 1 to n, such that for each value of i, each Ri represents a hydrogen atom, an alkyl, an aryl, a 1-(1-alkylalkoxy), a —[CH2—CH2—O]q-Alk radical where q is an integer of 1 to 20 and Alk represents an alkyl;
• R′ represents a hydrogen or an alkyl;
• Q represents a straight chain or branched alkylene group comprising 2 to 110 carbon atoms;
• A1 independently represents an alkylene or alkylidene group comprising 1 to 6 carbon atoms, or an arylene group;
• X1 is a hydrogen, an alkyl with 1 to 5 carbon atoms or a mono- or divalent cation, in particular an alkaline, alkaline-earth or ammonium cation, such that m1 is 1 when X1 represents a hydrogen, an alkyl with 1 to 5 carbon atoms or a monovalent cation, and m1 is 2 when X1 represents a divalent cation;
• R represents a hydrogen, an alkyl with 1 to 6 carbon atoms, an aryl or a -A2-PO3X22/m2 group where:
• A2 represents an alkylene or alkylidene group with 1 to 6 carbon atoms, or an arylene group,
• X2 represents a hydrogen, an alkyl with 1 to 5 carbon atoms or a mono- or divalent cation, in particular an alkaline, alkaline-earth of ammonium cation, such that m2 is 1 when X2 represents a hydrogen, an alkyl with 1 to 5 carbon atoms or a monovalent cation, and m2 is 2 when X2 represents a divalent cation,
• comprising the steps of:
• (co)polymerizing in a basic medium at least one ether of glycidol in the presence of an anionic initiator carrying a primary amine function, preferably an aminoalcoholate, to obtain a polyglycerol with primary amine termination,
• converting the primary amine function of the polyglycerol obtained at the preceding step to an amino-alkylene phosphonic group.