New side chain liquid crystalline polysiloxanes containing 1,3-dithiane or 1,3-dioxane rings as mesogenic side groups

Abstract

New liquid crystal materials: 2-\[p-(9-decenyloxy)phenyl]-5-(p -alkoxyphenyl)-1,3-dioxane(11) and 2-\[p-(9-decenyloxy)phenyl]-5-(p -alkoxyphenyl)-1,3-dithiane(12) were synthesized. The mesomorphic behaviour of these compounds was determined. Though the 1,3-dioxane-type monomer exhibited both SmA and nematic phases, the 1,3-dithiane-type monomer only exhibited a nematic phase. By the hydrosilylation of poly(methylhydrosiloxane) and these monomers, side chain polysiloxanes were synthesized. For the monomers, the transition temperatures of the nematic to isotropic transitions of 1,3-dioxane-type compounds are higher than those of the corresponding 1,3-dithiane-type compounds. However, in the polysiloxane polymer this relation reversed.