Characterization of polybutadiene-poly(ethyleneoxide) aggregates in aqueous solution: a light-scattering and small-angle neutron-scattering study.

For diblockcopolymers of polybutadiene-poly(ethyleneoxide) (PB-PEO) type, water is a selective solvent. In dependence of the length of both blocks and the block length ratio, these polymers form a multitude of self-assembled structures in solution. In the present work scattering methods are used to investigate the water-soluble polymer PB125-PEO155 . It is found to form long rodlike micelles, which are characterized with respect to the aggregate length L , the cross sectional radius RCS , the radial scattering length density profile sigma r, and the radial aggregation number Nrad. Model-independent as well as model-based approaches are used for the scattering data analysis. From dynamic light scattering (DLS) and static light scattering (SLS) experiments the weight averaged length Lw of these stiff elongated aggregates is determined to Lw=350 nm . Small angle neutron scattering (SANS) reveals a cross sectional radius of RCS=17 nm and in combination with results from the SLS the radial aggregation number is found to be Nrad=70 .