ToF-SIMS studies of poly(methyl methacrylate-co-methacrylic acid), poly(2,2,3,3,3-pentafluoropropyl methacrylate-co-4-vinylpyridine) and their blends

摘要

The surface properties of some polymers and their blends were investigated by both static and dynamic time-of-flight secondary ion mass spectrometry (ToF-SIMS). For poly(methyl methacrylate) (PMMA) and poly(methyl methacrylate-co-methacrylic acid) (MAA26, 26 denoting the mol% of methacrylic acid unit in the copolymer), the -OCOCH_3 pendant chain of MMA unit is the dominant group at the air-polymer interface. For poly(2,2,3,3,3-pentafluoropropyl methacrylate) (PFO) and poly(2,2,3,3,3-pentafluoropropyl methacrylate-co-4-vinylpyridine) (PF40, 40 denoting the mol% of 4-vinylpyridine unit in the copolymer), the air-polymer interface is almost completely occupied by the fluorinated pendant chain because of its extremely low surface energy. When PF40 and MAA26 are blended, the fluorinated component accumulates on the blend surface with the fluorinated pendant chain dominating the blend surface. The results of depth profiling by dynamic ToF-SIMS are in agreement with the static ToF-SIMS results. The fluorinated pendant chain of PF0 rearranges on the polymer surface at a depth of about 2.5 nm, while the fluorinated component accumulates on the blend surface at a depth of about 5 nm. For blends containing 1.5 wt.% of fluorinated component, practically all the fluorinated component accumulates on the blend surface. The dynamic ToF-SIMS results also verify that the hydrogen-bonding interaction between PF40 and MAA26 does not completely eliminate surface enrichment of the fluorinated component.