Chiral nematic phase in hydrogen-bonded blends of a side-chain smectic polymer with low molar mass dopants

Abstract

The possibility of chiral nematic mesophase induction in blends of a smectic A side-chain liquid-crystalline copolymer with low molar mass dopants was studied. The chirality of the initial copolymer was determined by the cholesterol optical active groups; however, in the individual state it was not able to form any chiral liquid-crystalline phases. We have shown that the induction of the chiral nematic phase becomes possible in blends of such a copolymer with low molar mass dopants that are stabilized by hydrogen bonding. Phase behavior and optical properties of the blends were studied with X-ray scattering, differential scanning calorimetry and polarizing microscopy. Owing to hydrogen bonding the blends are stable over a wide range of contents and temperatures. The nature of the end group in the dopant molecules is shown to have an important influence on the chiral mesophase induction concentration and the clearing temperatures of the blends. Temperature and concentration dependences of the selective reflection maximum wavelength in the chiral nematic phase were also studied.