Mesomorphism of Hybrid Siloxane-Triphenylene Star-Shaped Oligomers

ZELCER, ANDRÉS; DONNIO, BERTRAND; BOURGOGNE, CYRIL; CUKIERNIK, FABIO D.; GUILLON, DANIEL

CHEMISTRY OF MATERIALS

Año: 2007 vol. 19 p. 1992 - 2006

0897-4756

Novel hybrid triphenylene-carbosiloxane liquid crystalline monomers and star-shaped oligomers have been synthesized and their thermal behavior and liquid-crystalline properties analyzed and characterized. All compounds exhibit a columnar hexagonal phase and show, particularly the oligomers, a small tendency to crystallize. The substitution pattern on the central triphenylene moiety has very different effects on the crystal to columnar phase and columnar to isotropic liquid-phase transitions. A novel sterically induced superlattice has been found, and a model for the microscopic structure is proposed. One compound could be mechanically aligned, leading to well-oriented columnar liquid crystals.