Synthesis Of Side-Chain Liquid Crystalline Polymethacrylates Containing Fluorinated Diarylacetylene-Based Mesogenic Side Groups

Abstract

Abstract The synthesis and characterization of side-chain liquid crystalline polymetnacrylates containing fluorinated diphenylacetylenic and naphthylphenylacetylenic side groups are presented. The phase behavior of the prepared monomers and polymers was characterized by differential scanning calorimetry, optical polarizing microscopy, and x-ray diffraction. All of the methacrylate monomers exhibit no mesomorphic behavior. Polymers which contain eleven methylene units in their spacers reveal smectic mesomorphism. Polymers with a short spacer length, i.e., three or six methylene units, present either a nematic phase or no mesophase. The glass transition temperatures of the obtained polymers decrease as the spacer length increases. The polymers containing fluorinated naphthylphenylacetylenic side groups show a higher tendency to form a mesophase than those containing fluorinated diphenylacetylenic side groups. Incorporation of a lateral fluoro-substituent in the mesogenic core decreases not only the possibility to form a mesophase but also the thermal stability of the mesophase.