ToF-SIMS molecular characterization and nano-SIMS imaging of submicron domain formation at the surface of PS/PMMA blend and copolymer thin films

Thin films of polystyrene (PS)/poly(methyl methacrylate) (PMMA) blends and block copolymers were characterized by two different SIMS instruments. ToF-SIMS was used to obtain the molecular composition of the upper most surface while nano-SIMS allowed us to visualize the surface morphology with submicrometer lateral resolution. The blends and copolymers showed different effects on annealing. ToF-SIMS spectra of annealed blends showed a decrease in the concentration of PS and an increase in the concentration of PMMA as compared to the pristine sample. By contrast, the spectra of annealed copolymers showed a decrease in the concentration of PMMA and an increase in the concentration of PS. The result obtained from the nano-SIMS imaging of the blends and copolymers revealed the formation of submicron domains at the surface on annealin. In case of blends, the images showed a strong oxygen signal on the surface suggesting a higher PMMA concentration, while for copolymers, the oxygen signal was quite low. ToF-SIMS spectra combined with nano-SIMS images help to interpret the surface topographical changes that the PS/PMMA blend and copolymer thin films undergo on annealing. (C) 2004 Elsevier B.V. All rights reserved.