Structural changes of poly(butadiene)-poly(ethyleneoxide) diblock-copolymer micelles induced by a cationic surfactant:: Scattering and cryogenic transmission electron microscopy studies -: art. no. 011406

Micelles of the diblock copolymer poly(butadiene)-poly(ethyleneoxide) (B-40-b-EO62) and mixed micelles of this polymer with the cationic surfactant dodecyltrimethylammonium bromide (C(12)TAB) were investigated using static and dynamic light scattering and small-angle neutron scattering. It is shown that the surfactant induces a major structural change from large mainly rodlike aggregates to smaller spherical mixed micelles. The rodlike assemblies found in the absence of surfactant have a contour length L of ca. 500 nm and a diameter d approximate to30 nm. The spherical mixed micelles obtained upon addition of C(12)TAB possess a hydrodynamic radius of 15 nm and still contain several polymer molecules. The results of the scattering experiments are consistent with observations of the aggregates by cryogenic transmission electron microscopy.