A series of polyureas were synthesized through the reaction of aniline trimer with toluene-diisocyanate, diphenylmethane-4,4＇-diisocyanate, and hexamethylene-l,6-diisocyanate, respectively. The chemical structure of these polyureas was characterized and verified by FT-IR, ^1H NMR, elemental analysis, UV, XRD and CV. The conductivity of these polyureas ranged from 10^-7 to 10^-6 S/cm measured by four-point-probe instrument. Compared to the standalone aniline trimer, the stability （thermal stability and electrochemical stability）, response range and sensitivity of these polyureas are enhanced. The sensitivity of these polyureas DMF solution to pH value is superior to that of the standalone aniline trimer. The color of the polyureas DMF solution is greatly depended on pH value and the color change process is reversible, whenever from base to acid or from acid to base. These enhance- ments may give these polyureas more opportunities in order to be used as sensor materials.
