Photopolymerization and transport properties of liquid crystalline triphenylenes

The synthesis of polymerizable triphenylene derivatives with acrylate groups is described. The thermal properties and the photoconductive properties of the discotic monomers as well as of the polymers is investigated. In the mesophase typically photoinduced hole conductivity with a charge carrier mobility exceeding a value of 10(-4) cm(2)/Vs is observed with conventional time-of-flight (TOF) techniques. Different conditions for the photopolymerization of the acrylates in the mesophase are compared. The influence of the photoinitiators and the polymerization on the mesomorphic behavior and on the hole conductivity is described. Already the presence of small amounts of photoinitiator influences the packing within the mesophase. The polymerization further decreases the order and creates defects. This results in an at least one order of magnitude reduced charge carrier mobility at room temperature, compared to the monomer.