Determination of critical micelle concentration of polybutadiene-block-poly(ethyleneoxide) diblock copolymer by fluorescence spectroscopy and dynamic light scattering

In this study, critical micelle concentration (cmc) was determined for polybutadiene-block-poly(ethyleneoxide), PB(1800)-b-PEO(4000) amphiphilic diblock copolymer in aqueous media by fluorescence spectroscopy and dynamic light scattering (DLS) techniques. The fluorescence measurements were performed by using pyrene as a probe molecule in order to determine the cmc while the intensity of the scattered light from solutions was analyzed with the DLS technique. The cmc values determined by these two techniques for PB(1800)-b-PEO(4000) copolymer in aqueous solution at 25 °C were 3 ± 1 × 10− 7 and 6 ± 2 × 10− 7 mol/L, respectively. The results showed that DLS is as sensitive as fluorescence spectroscopy in determining the cmc of a copolymer, and that it is also capable of the simultaneous determination of cmc and hydrodynamic diameter of micelles in a copolymer micellar solution.