Synthesis and properties of phenyl benzoate-based and biphenyl-based liquid crystalline thiol-ene monomers

Novel Ph benzoate-based and biphenyl-based liq. cryst. thiol-ene monomers were synthesized and their properties studied. By varying the bridging unit and spacer length, the type of mesophase can be tuned from the low ordered nematic and smectic A phase in the case of the Ph benzoate-based monomers, to the highly ordered crystal E phase for the biphenyl-based monomers and their corresponding bromo precursors. The degree of order of the Ph benzoate-based materials was studied using the Haller method. Possible premature polymn. of these monomers was examd. by size exclusion chromatog. The materials exhibit low transition temps. and a high stability at typical handling times and temps. Consequently, these monomers are useful for in situ polymn. with anisotropic inert solvents, which could potentially lead to new architectures and enhanced electrooptical properties of devices. The use of the biphenyl-based monomers appears to be of limited use for polymns. in anisotropic soln. However, as a result of their intrinsic high degree of mol. order, these monomers form a particularly interesting class of reactive materials that can be bulk polymd. to give main chain polymers with highly defined mech. and optical or electrooptical properties. [on SciFinder (R)]