Langmuir–Blodgett film fabricated with soluble imidized polyimide

A soluble imidized polyimide containing pendant carboxylic groups was used to prepare Langmuir–Blodgett films. The soluble imidized polyimide was synthesized from 4,4′-(hexafluoro isopropylidene) diphthalic anhydride (6FDA) and 3,5-diaminobenzoic acid (DABz) using a one-pot method. The carboxyl groups were reacted with octadecylamine (ODA) to form polymeric amphiphilic salt that was spread on the water surface and transferred to solid substrates to prepare the LB film. The ODA in the film was removed by thermal treatment, chemical treatment and dissolution. XPS, AFM, reflectance FT-IR and ellipsometry were used to characterize the films. The thermal and chemical treatments were more efficient than dissolution to remove ODA. The film had a smooth surface after thermal treatment.