Analysis Of Homopolymer Distribution In A Polymer Blend Thin Film By Anomalous Grazing Incidence Small-Angle X-Ray Scattering At The Bromine K-Edge

Polystyrene-block-poly(4-hydroxystyrene) (PS-PHS)/poly(4-hydroxystyrene) brominated (Br-PHS) blend thin films were analyzed using anomalous grazing incidence small-angle X-ray scattering (anomalous GISAXS or AGISAXS), which provides sensitive elemental analysis using the energy dependence of the atomic scattering factor near the absorption edge. In this study, AGISAXS measurements were performed using energies near the absorption edge of the bromine atom to elucidate the dispersion state of the brominated homopolymer in the blend thin film. The PS-PHS/Br-PHS blend thin film formed hexagonally packed cylinders perpendicular to the silicon substrate. The energy-dependent GISAXS profiles proved the formation of core-shell cylindrical structures. The fitting analysis of the in-plane GISAXS line profiles of the hexagonally packed cylindrical domains with paracrystalline distortion revealed that Br-PHS segregated to the PS-PHS interface to reduce the interfacial energy of the PS and PHS.