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Depth Profiling of Block Copolymer Nanostructures in Films by Small‐ A ngle X‐Ray Scattering Using an X‐ R ay Microbeam
Author(s) -
Sakurai Shinichi,
Kimura Go,
Mizuno Yohei,
Masunaga Hiroyasu,
Ogawa Hiroki,
Ohta Noboru,
Yagi Naoto
Publication year - 2013
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.201350515
Subject(s) - scattering , materials science , small angle x ray scattering , microbeam , perpendicular , surface roughness , optics , surface finish , nanostructure , copolymer , polystyrene , composite material , nanotechnology , geometry , polymer , physics , mathematics
Summary We applied the microbeam two‐dimensional small‐angle X‐ray scattering (2d‐ µ SAXS) technique in order to characterize orientation of polystyrene (PS) microdomains as a function of the distance from the free surface of a sample sheet down to the surface facing to the substrate, for depth profiling for spontaneous perpendicular orientation of PS cylinders in the matrix of polyethylenebutylene (PEB) in a PS‐ b ‐PEB‐ b ‐PS triblock copolymer thick sheet as thick as ∼0.5 mm. It has been revealed that near the free surface the cylinders were randomly oriented down to ∼70 µm in depth. Although this might indicate that the surface effect, which preferentially dictates cylinders to be oriented parallel to the surface, can propagate for such a long distance, 70 µm is unusually huge as compared to the general knowledge of the surface effect propagating at most for 1 µm. Experimentally examining further, we finally conclude that the 2d‐ µ SAXS depth profiling overestimates the surface effect. This unfavorable conclusion may be ascribed to surface roughness of the sample sheet subjected to the measurement, and in order to obtain a good result a big effort is required to prepare the surface as flat as possible.