Preparation and surface observation by scanning probe microscope of C₆₀-containing polyimide Langmuir-Blodgett film

Langmuir-Blodgett (LB) film of C₆₀-containing polyimide were prepared via the corresponding polyamic acid alkyl amine salt (the precursor of polyimide) LB film using the precursor method. Absorption bands in both the precursor and polyimide LB films deposited on quartz plate were observed at 208, 261 and 340 nm, which were typical absorption of C₆₀. Changing of carbonyl absorption from the precursor polyamic acid alkyl amine salt to polyimide, and removal of the long alkyl chain were elucidated by Fourier transform infrared spectroscopy (FTIR) spectra. The atomic force microscope (AFM) images of the precursor monolayer film indicated the flat surface, whereas islands attributed to the self-aggregated alkyl chain were observed in the friction force microscope (FFM) image of the same area of AFM. After imidization by heating the precursor monolayer film at 160°C for 3 h, holes with the depth of 1.8 nm were seen at the place of the aggregated alkyl chain in the precursor monolayer.