Frustrated phases induced in binary mixtures of hockey-stick and chiral rod-like mesogens

Abstract

Two liquid crystalline compounds with different shapes and chirality aspects have been used to prepare binary mixtures. An achiral hockey stick mesogen exhibiting a nematic-smectic C synclinic-smectic C anticlinic phase sequence has been blended with a chiral rod-like mesogen with a SmA*-ferroelectric (FE) SmC*-antiferroelectric (AF) SmC A * phase sequence. Several frustrated phases (blue phases, TGBA and TGBC phases) have been induced in broad temperature and concentration ranges. By tailoring the composition of the chiral compound we succeeded in preparation of mixtures with unusual mesomorphic behaviour. We demonstrate a new system showing chiral nematic and antiferroelectric phases in its phase sequence.

Frustrated smectic liquid crystalline phases in lactic acid derivatives

“…The phase diagram of the studied system was demonstrated in Ref. [17] and exhibited a variety of mesophases not present in starting compounds. We observed that even a small amount of the chiral compound induces the TGBA and TGBC phases.…”

“…Besides, in the TGBC phases square grid textures may appear (see Figure 8). [17] It is necessary to point out that variety of textural features and their similarity with neighboring phases when reaching the TGB phases on heating or cooling (paramorphic features) make identification of TGB mesophases phases just by textures rather difficult.…”

“…Nevertheless, in mixtures these phases exist within a very wide concentration range. [17] The compounds for mixtures have been selected in a way that their mesomorphic properties exist roughly in the same temperature range. The phase diagram of the studied system was demonstrated in Ref.…”

Banana-calamitic Dimers: Further Variations of the Bent-core Mesogenic Unit

“…The modular conception does not need such high expenditure of synthetic work. Broad heterophasic ranges in the diagrams show a disadvantage of this approach [49][50][51][52][53][54][55].…”

Chiral random grain boundary phase of achiral hockey-stick liquid crystals

“…[21][22][23][24][25][26][27][28][29][30] These molecules typically comprise a central core to which arms of substantially different length are attached. Hockey-stick mesogens exhibit several exotic phases and effects associated with their asymmetric shape, including the dual-characteristic nematic phase (which displays both calamitic and bent-core properties), 31 the occurrence of two polymorphic, tilted smectic phases (the SmC S and SmC A phases) induced by a molecular conformation change, [32][33][34] the coexistence of two different molecular tilts at the nematic-SmC transition, 35 the macroscopically chiral nematic and dark conglomerate phases, 36 the frustrated blue and twist grain boundary phase induced by chiral, rod-like mesogens, 37 and a layer thinning transition. 38 In this paper, we report a new hockey-stick mesogen (COBOXD), an achiral molecule with a exible alkyl chain attached to one end of an asymmetric, rigid, bent core.…”