Poly[styrene-b-maleated (ethylene/butylene)-b-styrene] (mSEBS) block copolymers and mSEBS/inorganic nanocomposites: I. Morphology and FTIR characterization

Self-assembled, [block copolymer]/[pure silicate and ORMOSIL] nanocomposites were created via sol-gel processes for silicate and organically-modified silicate (ORMOSIL) monomers in the presence of sulfonated maleated poly(styrene-b-ethylene/butylene-b-styrene) (mSEBS). Microscopic and small angle X-ray scattering (SAXS) studies showed that unmodified mSEBS has hexagonal packed PS cylinder morphology, but sulfonation causes the morphologies to be frustrated. The morphology of pure silicate nanoparticle-containing nanocomposites is phase separated, although further frustrated. The morphologies of the ORMOSIL-modified materials were different, less-ordered and show the influence of the nature of the organic group on self-assembly. Despite differences in morphology, degree of order, and different inter-domain spacings, all but the pure silicate-containing hybrid have the same PS domain width (25-30 nm). The dispersed nanoparticles are roughly spherical and some can grow to exceed the block copolymer domain sizes. All filled samples have inter-domain spacings, derived by SAXS analysis, that are larger than that of the corresponding unfilled sulfonated mSEBS, which reflects insertion of silicate or ORMOSIL structures. FTIR spectroscopy indicated successful Si-O-Si bond formation, which shows that the inserted particles are indeed crosslinked.