The present invention relates to the synthesis of an associative acrylic (co)polymer by aqueous emulsion radical polymerization. The (co)polymer contains at least one oligomer of acrylic acid represented by the formula (I): where n is an integer ranging from 1 to 10. The oligomer is prepared from acrylic acid at a temperature of between 50° C. and 200° C. in the presence of a basic or acid catalyst, water, and polymerization inhibitors. The present invention also relates to the associative acrylic (co)polymer obtained from the method and also to the use of this (co)polymer as a thickener in various formulations.