A sulphur-comprising polyaromatic polyamine compound can be used as a monomer or prepolymer, when n is different from zero, in the synthesis of polyurea. The compound corresponds to the formula (I): H2N—Ar1—NH—CH2—CH(OH)—(CH2)m—O—Z1—O—(CH2)m—CH(OH)—CH2—[X]n—HN—Ar2—NH2 in which X represents the string: —HN—Ar3—NH—(CH2)—CH(OH)—(CH2)m—O—Z2—O—(CH2)m—CH(OH)—(CH2)— and in which n represents an integer equal to zero or different from zero; m, which are identical or different, represent an integer within a range from 1 to 10; Z1 and Z2, which are identical or different, represent a divalent bonding group comprising from 1 to 30 carbon atoms; and Ar1, Ar2 and Ar3, which are identical or different, each represent a phenylene group, at least one of these phenylene groups bearing one, two, three or four groups of formula —Sx—R in which “x” is an integer from 1 to 8 and R represents hydrogen or a hydrocarbon group which can comprise a heteroatom and which comprises from 1 to 10 carbon atoms.