Ultrathin films of polymerized smectic liquid crystals. A study of the polymerization process

We have studied the photopolymerization of an amphiphilic compound containi ng a biphenyl group which has, at one end, a fumarate propyl ester and, at the other, a vinyl group. We have photopolymerized the compound when it was spread as a monolayer at the air/water interface and have then assembled i t into multilayer structures by the Langmuir-Blodgett technique. We have al so formed multilayers of the monomers and then photopolymerized them. Both kinds of films have been characterized by X-ray diffraction, by polarizing microscopy, and by UV absorption spectroscopy. When monomers are assembled into a layer structure and are then irradiated with UV light, they will onl y polymerize when in the smectic phase, which-can be produced by heating th e film to a temperature above 54 degrees C, but when the multilayer consist s of two-dimensional crystals, it will not polymerize. Because polymerizati on can take place at the air/water interface, we think it likely that the p olymerization process takes place within layers rather than between layers.