Observation of polyamic acid alkylamine salts (PAAS) Langmuir/Langmuir-Blodgett films using Brewster angle microscopy (BAM)

Monolayer phases on the water subphase such as Langmuir (L) films and the phase transitions from gas phase to solid phase via liquid phase are observed using Brewster angle microscopy (BAM). BAM is also used to observe the Langmuir-Blodgett (LB) films. In this paper, polyamic acid alkylamine salts (PAAS) is used for forming L/LB films and π-A isotherm shows the surface pressure at each phase. We have obtained instantaneous BAM images as the surface pressure increases. Images of the several LB films were compared with data from ellipsometry which was used to measure the film thickness. Images of both L/LB films were analyzed with a computer for points of brightness. As a result, we have obtained molecular distribution and the film thickness is in proportion to the surface pressure