We here report the self-organization process of poly(styrene-b-ethylene/butadiene-b-styrene) (SEBS) triblock copolymer chains physically adsorbed on a non-neutral surface. Spin-cast SEBS thin films were prepared on silicon (Si) substrates and then annealed at a high temperature far above the bulk glass transition temperatures of the two constituent blocks. To reveal the buried interfacial structure, we utilized solvent rinsing processes and a suite of surface-sensitive techniques including ellipsometry, X-ray reflectivity, atomic force microscopy, and grazing incidence small angle X-ray scattering. We revealed that the SEBS chains form two different chain structures on the substrate simultaneously: (i) “flattened chains” with the average height of 2.5 nm but without forming microdomain structures; (ii) “loosely adsorbed chains” with the average height of 11.0 nm and the formation of perpendicularly oriented cylindrical microdomains to the substrate surface. In addition, the kinetics to form the perpendicular-oriented cylinder was sluggish (∼200 h) and proceeded via multistep processes toward the equilibriumstate. We also found that the lateral microdomain structures weredistorted, and the characteristic lengths of the microdomains wereslightly different from the bulk even after reaching “quasiequilibrium”state within the observed time window. Furthermore, we highlight thevital role of the adsorbed chains in the self-assembling process ofthe entire SEBS thin film: a long-range perturbation associated withthe adsorbed chains propagates into the film interior, overwhelmingthe free surface effect associated with surface segregation of thelower surface tension of polystyrene blocks.
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