Photo-initiated polymerization of liquid crystalline thiol-ene monomers in isotropic and anisotropic solvents

We report on the photoinitiated polymn. of Ph benzoate-based liq. cryst. (LC) thiol-ene monomers in isotropic and anisotropic solvents. The mixing behavior of the thiol-ene monomers with anisotropic cyanobiphenyl solvents was investigated, and unique reactive LC mixts. are formed that exhibit variable mesophases at ambient temps. Using size exclusion chromatog., the conversion of the thiol-ene monomers was studied in isotropic solvents and in anisotropic solvents as a function of several parameters, such as the irradn. time, polymn. temp., and monomer concn. Indications for the existence of a polymn. ceiling temp. effect were obsd. which was more pronounced for lower initial monomer concns. The in situ photopolymn. of the LC thiol-ene monomers in anisotropic media leads to a variety of morphol. structures, ranging from intriguing threadlike architectures to dendritic cryst. structures. The morphol. changes that occur during the polymn. process are complex, and several approaches toward the enhanced control over the resulting morphologies are discussed. The results and insights presented here could potentially lead to new architectures and enhanced optical and electrooptical properties of devices. [on SciFinder (R)]