Morphology and chemical structure of poly(methyl methacrylate) surfaces and interfaces: restructuring behavior induced by the deposition of SiO2

The surface morphology, molecular structure, and the surface restructuring behavior after the deposition of a SiO2 layer on poly(methyl methacrylate) (PMMA) have been investigated by using atomic force microscopy (AFM) in contact mode and sum-frequency generation (SFG) vibrational spectroscopy. AFM images show that the surface of PMMA is quite flat and sporadically contains dendritic features, which are micro-crystalline structures of PMMA. From the SFG measurements, the ester methyl groups of PMMA are pointed away from the surface plane at least in the surface region. By depositing a SiO2 film, the SFG signal intensity is significantly reduced, indicating that the CO and the ester methyl groups are aligned nearly parallel to the surface plane.