A water soluble PU macromonomer was synthesized starting from polyethylene glycol oxide, 2,4 toluene diisocyanate, using hydroxyethyl acrylate as end chain termination agent. It is revealed that the intrinsic viscosity of the aqueous solution and cloud point of the macromonomer became lower, and the association of the macromonomer became apparent as hydrophobic mass fraction in the macromonomer composition increased. It is also found that the aggregation state of PU macromonomer in aqueous solution is strikingly dependent on temperature and concentration. Hydrophobic association occurred between macromonomers themselves as the concentration of aqueous solution increased. At higher temperature the HLB value of the macromonomer became lower, and micelle formed at the temperature over 75 ℃ .
