Interaction of blockcopolymer micelles as probed by small-angle neutron and by small-angle X-ray scattering

The analysis of the interaction of micelles formed by a blockcopolymer is given by means of small-angle X-ray (SAXS) and small-angle neutron scattering (SANS). The blockcopolymer consists of poly(styrene) and poly(ethylene oxide) (molecular weight of each block: 1000 g/mol) and forms well-defined micelles (weight-association number: 400, weight-average diameter: 15.4 nm) in water. The internal structure has been studied previously (Macromolecules 29:4006 (1996)) by SAXS. There it has been shown that the micelles are spherical objects. The structure factor S(q) as a function of the scattering vector q(q=(4π/λ) sin (ϑ/2); λ: wavelength of the radiation in the medium; ϑ: scattering angle) can be extracted from both sets of small-angle scattering data (SANS: q ≤ 0.4 nm−1; SAXS: q ≤ 0.6 nm−1). It is shown that particle interaction in the present system can be described by assuming soft interaction which is modeled by a square-step potential.