INTERACTION OF BLOCK-COPOLYMER 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 p oly(ethylene oxide) (molecular weight of each block: 1000 g/mol) and f orms well-defined micelles (weight-association number: 400, weight-ave rage diameter: 15.4 nm) in water. The internal structure has been stud ied previously (Macromolecules 29:4006 (1996)) by SAXS. There it has b een shown that the micelles are spherical objects. The structure facto r S(q) as a function of the scattering vector q(q = (4 pi/lambda) sin (theta/2); lambda: wavelength of the radiation in the medium; theta: s cattering angle) can be extracted from both sets of small-angle scatte ring data (SANS: q less than or equal to 0.4 nm(-1); SAXS: q less than or equal to 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.