A simple synthetic route for preparing a thiophosphate-containing pseudodendritic polyethyleneiminated polyoxypropylenediamine, D400(EI)(x)P, is presented. The number of ethyleneimine group (EI) in D400(EI)(x)P was determined by H-1-and C-13-NMR to be 4.3 for D400(EI)(4)P and 8.9 for D400(EI)(8)P, and the extent of branch was quantitatively determined using potentiometric titration. The numbers of thiophosphate groups per thiophosphate-containing pseudodendritic polymers molecule for D400(EI)(0)P, D400(EI)(4)P, and D400(EI)(8)P were calculated by elemental analyses of sulfur content. The AW performance of these synthesized thiophosphate-containing pseudodendritic polymers was examined by measuring the temperature of oil, and the frictional coefficient and electrical contact resistance between the two metal surfaces. More thiophosphate groups on either side of D400(EI)(8)P are found to increase the electrical contact resistance due to the chemical adsorption of thiophosphate groups onto metal surfaces, forming a thick layer and reducing operating time required to form the adsorption layer. Interestingly, the adsorption layers markedly reduce the frictional coefficient (similar to 0.012) and limit the increase in oil temperature (similar to 90 degreesC) throughout the entire period of AW test, reducing weight loss of the metal (0.1 mg). (C) 2004 Wiley Periodicals, Inc.