Polymer-dispersed liquid crystal monolayers

The first examples of two-dimensional polymer-dispersed liquid crystals (PDLCs) have been prepared via the Langmuir-Blodgett technique and analyzed using tapping mode atomic force microscopy (TiMAFM). Characterization of the thermodynamics, polymerization kinetics, and topology of mixtures of 2-pentadecylaniline (2PDA) and a ferroelectric liquid crystal termed 10PPB2 was investigated. Systematic pressure versus area isotherms indicate that the mixed monomer/liquid crystal exists as a phase-separated monolayer after the evaporation of the spreading solvent, typical of a solution-induced phase separation (SIPS). Interfacial polymerization of the monomer in the presence of the liquid crystal has been accomplished. Langmuir-Blodgett-Kuhn (LBK) films obtained by transferring the polymer/liquid crystal system on freshly cleaved mica surfaces revealed a polymer-dispersed liquid crystalline system with circular liquid crystalline domains trapped within a poly(alkylaniline) matrix. Statistical characterization of domain parameters (i.e. domain density, mean diameter, and polydispersity) was performed, and the effect of monolayer and polymerization conditions on these parameters was investigated. From these studies it was found that domain morphology could be controlled by the manipulation of monolayer spreading and compression rates. The high anisotropy and controlled symmetry of these monolayer liquid crystal domains make them attractive models of bulk PDLCs.