Short-chain poly(dimethylsiloxane)-poly(ethylene oxide) (PDMS-b-PEO) diblock copolymers with different ratios of the hydrophilic to hydrophobic segments were synthesized via coupling of end-functionalized PDMS and PEO homopolymers. Their aggregation behavior was investigated by tensiometry, fluorescence, and cryogenic transmission electron microscopy. Interestingly, the critical aggregation concentration of the surfactants increased with increasing length of the hydrophobic chain. The electron microscopy studies showed that the surfactants preferentially aggregate into vesicles and lamellar structures.