We describe the synthesis and associative behavior in water of a strictly alternating comblike ampbiphilic polymer based on paly(ethylene glycol) (PEG). The polymer has a strictly alternating sequence of PEG blocks (M-w = 8000) of low polydispersity and hydrophobic 18 carbon-atom alkyl pendent chains. Three copolymers with M-w = 28 000, 68 000, and 113 000 were prepared. The associative behavior of the polymer of molecular weight 28 000 (on average about 3 PEG-C18 sequences per chain) in water was studied by static and dynamic light scattering, spectrofluorimetry, and viscosity measurements. The behavior resembles that of hydrophobically end capped (i.e., telechelic) PEG. Flowerlike micelles, each containing approximately 14 hydrophobes, are formed by the association of about; four to five polymer chains.