Langmuir–Blodgett film fabricated with dendrimer modified polyimide

Langmuir–Blodgett films were prepared from a soluble polyimide modified by a dendrimer wedge (NMPI). The terminal group of the dendrimer can be formed as nitrile or ester groups. The specific area and collapse pressure of the Langmuir layers on the water surface could be controlled by appropriate choice of the terminal group of the dendrimer wedge and subphase pH. ODA (octadecylamine) and AA (arachidic acid) were employed as spacers to enhance the stability of the Langmuir film. AA can improve the stability of NMPI Langmuir film to a higher extent than ODA because of the higher interaction between the NMPI and AA. The long alkyl chain compounds were removed from the LB film subsequently by thermal treatment. The LB films were characterized by polarized FT-IR, UV, VASE and XPS. The refractive index of the LB film increased after thermal treatment; however, it is lower than that of the unmodified polyimide LB film. This work illustrates the influence of the dendrimer wedge in forming porous multilayer films.