Distributions of Deuterated Polystyrene Chains in Perforated Layers of Blend Films of a Symmetric Polystyrenepoly(methyl methacrylate).

We have examined the spatial distributions of polymer chains in blend films of weakly segregated polystyrenepoly(methyl methacrylate) [P(S--MMA)] and deuterated polystyrene (dPS). By fine-tuning the composition (ϕ = 63.8 vol %) of the total PS/dPS component and annealing temperature (230 and 270 °C), P(S--MMA)/dPS blend films mainly form perforated layers with a parallel orientation (hereafter PLs). The distributions of dPS in PLs were probed by grazing-incidence small-angle neutron scattering (GISANS) and time-of-flight neutron reflectivity (ToF-NR). GISANS and ToF-NR results offer evidence that dPS chains preferentially locate at the free surface and within the PS layers for blend films that were annealed at 230 °C. Upon annealing at 270 °C, dPS chains distribute within PS layers and perforated PMMA layers. Nevertheless, dPS chains still retain a surface preference for thin films. In contrast, such surface segregation of dPS chains is prohibited for thick films when annealed at 270 °C.