Novel glass-forming liquid crystals. II. Systems containing 1-phenyl-2-(6-cyanonaphth-2-yl)ethyne as a high optical birefringence moiety

Abstract

A new series of glass-forming molecular materials have been synthesized that incorporate 1-phenyl-2-(6-cyanonaphth-2-yl)ethyne as the high optical birefringence nematogenic moiety and a diphenylacetylenic group as part of the chiral moiety containing (S)-(−)-1-phenylethanol. To facilitate the preparation of chiral nematic systems, the key intermediate, i.e. 1,3,5-cyclohex-anetricarboxylic anhydride chloride, was synthesized and characterized. The thermotropic and optical properties of all products and the blends prepared therefrom were characterized by polarizing optical microscopy, differential scanning calorimetry, and UV-VIS-NIR spectrophotometry. It was found that all the resultant molecular materials readily form glasses with a T _g of around 60°C while showing no residual crystallinity below T _g or tendency toward crystallization by heating above T _g. Furthermore, binary blends showed a decreasing degree of miscibility at an increasing extent of structural dissimilarity with the all-chiral/all-nematic systems exhibiting significant phase separation at a chiral mole fraction of 0.16.