A series of novel nonionic functional polyurethane surfactants were synthesized by the polycondensation of 2,4-toluene dfisocyanate with poly(propylene oxide) (weight-average molecular weight = 400, 1000, or 2000) and monoallyl-end-capped poly(ethylene oxide). The chemical structure of the polyurethane surfactants was determined by Fourier transform infrared and H-1-NMR, and the effects of the concentration, salt, rest time, and temperature on the surface tension were investigated. These polymeric surfactants exhibited excellent surface activity. Sample III, which was synthesized with monoallyl-end-capped poly(ethylene oxide) (number-average molecular weight = 1000), poly(propylene oxide) (number-average molecular weight = 2000), and tolylene diisocyanate, could reduce the surface tension to 37.6 mN/m at a concentration of 0.06 mol/L at 25 degrees C. All polyurethane surfactants synthesized in this study had low critical micelle concentrations (ca. 10(-4) to 10(-5) mol/L) and could reduce the Surface tension even at very low concentration levels. Moreover, the surface tension decreased with an increase in the temperature or the concentration of the polyurethane surfactants. The addition of salt resulted in a decrease in the surface tension, and it took some time for the polyurethane surfactants to reach a constant surface tension value. UV spectra were found to be very useful for determining the critical micelle concentration. (c) 2006 Wiley Periodicals, Inc.