Direct visualisation of micelles of Pluronic block copolymers in aqueous solution by cryo-TEM

Micelles formed by (ethylene oxide) (propylene oxide) (ethylene oxide) triblock copolymers (Pluronic F127 and L64) in aqueous solutions have been visualised by cryogenic transmission electron microscopy (cryo-TEM). The resolution achieved allows detailed inspection of the individual micelles, their size, shape, core-shell structure as well as long-range order. The dependence of the microstructure on the concentration of the solution as well as on the type (block sizes) of the Pluronic polymer are reported and demonstrate the sensitivity of the method to these parameters.