Thin films of poly(styrene‐block‐methyl methacrylate) diblock copolymer [P(St‐b‐MMA)] with thickness ca. 50 nm were prepared by a dip‐coating method. The surface Tg for the P(St‐b‐MMA) thin film was evaluated on the basis of the temperature‐dependent X‐ray photoelectron spectroscopic (TDXPS) measurement. The temperature at which the surface composition started to change was defined as the glass transition temperature, Tg, at the surface region. It was revealed that the surface Tg for P(St‐b‐MMA) was much lower than that for its bulk sample. Also, the depth dependence of Tg for P(St‐b‐MMA) was investigated on the basis of the combination of TDXPS and the angular‐dependent XPS (ADXPS) method. Tg for P(St‐b‐MMA) decreased with a decrease in distance from the outermost surface. The molecular weight dependence of the surface Tg for P(St‐b‐MMA) was more pronounced than that in the bulk sample, and that was expressed as a function of M −(0.45±0.02)n.
All Science Journal Classification (ASJC) codes