Effect of the skeletonization process on vapor sorption into Langmuir-Blodgett multilayers

One of simplest Langmuir-Blodgett films is a stack of fatty acid layers bri dged together by divalent cations. A certain fraction of fatty acids remain protonated, an amount dictated by aqueous subphase conditions during film deposition; these films are thus comprised of two components with different solubilities in organic solvents. We investigated the so-called skeletoniz ation process that occurs when behenic acid multilayers are immersed in ben zene. In particular, we used a quartz crystal microbalance to measure the l oss of film mass and found that it agrees well with the amount of protonate d acid in the original film. We also used the quartz crystal microbalance t o investigate the equilibrium vapor sorption properties of unmodified films and compared them to those of skeletonized films. Both types of films take in nearly the same amount of water but absorb distinctly different amounts of selected organic vapors.