TIT# Morphological changes in SBS block copolymers caused by oil extension as determined by absolute small angle x-ray scattering AUT# Polizzi, S.; Stribeck, N.; Zachmann, H. G.; Bordeianu, R. SOU# Colloid Polym. Sci. (1989), 267, 281-291 LOC# xv006 @selbst.ftx CLA# COM# APP# MAT# ABS# A series of SBS block copolymers diluted with different amounts (0 - 60 weight-%) of three different kinds of oil were investigated: (1) Lithene PM (a low molecular weight polybutadiene); (2) a paraffinic mineral oil with its electron density close to that of the polybutadiene (PB) phase; (3) a highly aromatic mineral oil with an electron density close to the polystyrene (PS) phase. All the oils seem to go into the polybutadiene matrix. Paraffinic oil and lithene form a homogeneous phase with PB; the aromatic oil at low concentration mixes with the PB with a high level of inhomogeneity, while at higher concentration partial phase separation occurs. In the undiluted polymer, styrene forms cylinders in hexagonal packing. The distance between cylinders (~ 43 nm) is not significantly changed upon dilution up to 33 weight-%. Previously proposed changes in the morphology of PS domains at larger oil contents can be related to observed changes in the long period, in the chord distributions, and in the homogeneities of the phase (density fluctuations). The electron density difference obtainde for pure SBS is lower than the theoretical one calculated from the densities of pure PS and pure PB. Dilution by paraffinic oil improves the phase separation.