Rapid scan time-resolved infrared spectroscopy has been used to study in situ the crystallization induced by evaporation in an aqueous solution of a triblock copolymer, Pluronic F127. A droplet of the solution was cast on a silicon substrate and the evaporation followed by an infrared microscope in transmission mode. The evaporation rate of water, in the last stage of the process, has been shown to be correlated to the changes in the block copolymer; four different stages can be distinguished. The block copolymer passes from an amorphous micellar state in water to a partially crystallized phase in well-defined stages of the evaporation; the complete change from amorphous to crystalline state of Pluronic F127 is observed only after all water is evaporated.