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In this work, we present the synthesis of two analogues of a lactic acid derivative selectively deuterated on phenyl and biphenyl moieties together with a detailed investigation of their properties within the Twist Grain Boundary smectic A* (TGBA*), the ferroelectric Smectic C* (SmC*) and the crystal E phases. The main structural features of the two liquid crystalline phases, namely TGBA* and SmC* phases, were determined by polarising optical microscopy, differential scanning calorimetry, electro-optical techniques, Small Angle X-ray Scattering (SAXS) and 2H Nuclear Magnetic Resonance (2H NMR) measurements. Preliminary results from Neutron Spin-Echo (NSE) spectroscopy, a technique rarely applied to study chiral liquid crystalline materials, are reported. The effect of the external magnetic field on the supramolecular structure of the ferroelectric phase was studied by means of 2H-NMR experiments under different external magnetic fields. The supramolecular and orientational ordering properties of this ferroelectric lactic acid derivative and its deuterated homologues are discussed in the frame of actual knowledge in the field of ferroelectric liquid crystal materials. [ABSTRACT FROM AUTHOR]

Several new comb-like stereoregular cyclolinear methylsiloxane copolymers exhibiting the self-assembling behaviour have been designed and studied. For the resulting macromolecular materials, the chiral mesogenic unit, namely (S)-(-)-4-[1-ethoxycarbonyl)ethoxycarbonyl]phenyl-4′-[11-tetramethyldisiloxyl)-undecenyloxy)-biphenyl-4′-carboxylate, has been used as a side group to assure the mesomorphic behaviour. The mesomorphic and structural properties were studied by the polarising optical microscopy, differential scanning calorimetry and small-/wide-angle X-ray diffraction techniques. The designed copolymers form the orthogonal smectic A* and the tilted smectic C* phases over relatively broad temperature range, down to room temperatures. The obtained results are discussed in order to contribute to better understanding of the molecular architecture-nano-organisation relationship for a specific type of macromolecular system based on the lactic acid derivatives used as a flexible side groups. [ABSTRACT FROM AUTHOR]

Design of binary and multicomponent liquid crystalline mixtures is a very powerful tool to reach the desired self-assembling properties. Beyond many advantages, this method has a distinct negativity – it is very material-consuming. While working with unique chiral materials in the research laboratory, this problem can be solved by applying miscibility study by the contact preparation method. In this work, the miscibility studies of lactic acid derivatives and non-chiral/chiral liquid crystalline molecules of different structure have been done in order to establish the phase diagrams. Special attention is focused on the ferro(antiferro)electric smectic phases. [ABSTRACT FROM AUTHOR]

Two series of new liquid crystalline lactic acid derivatives with a terminal ester group have been synthesised. The effect of this ester unit and the length of its alkyl chain on the mesomorphic and dielectric properties of the compounds exhibiting a broad temperature range of chiral smectic phases have been studied. We found that the mesomorphic behaviour and phase transition temperatures are strongly affected by the molecular architecture. Depending on the alkyl chain length in the terminal ester unit, the studied materials exhibited paraelectric smectic A*, ferroelectric tilted smectic C* and antiferroelectric smectic CA* phases over a broad temperature range. The physical properties of the compounds have been studied by optical polarising microscopy, differential scanning calorimetry, electro-optic measurements, small-angle X-ray scattering and dielectric spectroscopy. Furthermore, the homologues with short terminal alkyl chains showed a very small layer shrinkage at the transition from the orthogonal SmA* to the tilted SmC* phase, which is a characteristic feature of ‘de Vries-type’ behaviour. [ABSTRACT FROM AUTHOR]

Mixing of structurally similar self-assembling materials is a powerful tool to tune their mesomorphic, orientational or dielectric properties. We present design and study of binary mixtures composed of two newly designed chiral lactic acid derivatives with a similar structure but different geometry of the molecular core. One compound possesses a monotropic ferroelectric SmC* phase while another shows a direct isotropic – crystalline phase transition. It has been shown that the binary mixtures possess the eutectic behaviour and the ferroelectric phase temperature range has been extended. Moreover, for certain mixtures induced liquid crystalline phases, namely the cholesteric or TGBAphases, were detected. [ABSTRACT FROM AUTHOR]

The effect of several polar ester linkage groups incorporated in the molecular core of a chiral lactic acid derivative on self-assembling properties has been investigated by polarizing optical microscopy, small angle X-ray diffraction, differential scanning calorimetry, optical and electro--optical studies. The compound possesses the paraelectric smectic A* (SmA*) and ferroelectric smectic C* (SmC*) phases over a broad temperature range. Mesomorphic behaviour, spontaneous polarization, birefringence, optical transmission, dielectric anisotropy and structural properties of the self-assembled chiral material have been determined. The obtained results are discussed and compared with that of other liquid crystalline materials. Experimentally determined spontaneous polarization and tilt angle values are also used to elucidate the nature of SmC* to SmA* phase transition. The effect of polar ester linkages in the molecular core has also been discussed. [ABSTRACT FROM AUTHOR]

New liquid crystalline (LC) materials were prepared by derivatization of lactic acid. First compound possesses the lactic acid unit as the only chiral center and the second group of LC materials contains two chiral centers. Mesomorphic properties of both the newly synthesized LC materials were studied and the presence of the SmA*–SmC* or exhibit the twist grain boundary (TGB) phases, namely TGBA and TGBC, in a wide range of temperatures down to the room temperature was established. The potential of high-performance liquid chromatography (HPLC) applying chiral stationary phases to separate enantiomers or diastereoisomers of the synthesized LC compounds was evaluated. Two different brands of commercial chiral sorbents, Lux Amylose-2 and Chiralpak AD-3, both based on modified silica with derivatized polysaccharide, were employed in the development of separation procedures. The optimized chiral HPLC method provided a baseline separation of the individual enantiomers for the LC material containing one chiral center. In the case of the more complex compound with two asymmetric carbon atoms, where four isomers exist, partial separation was reached only using the current chiral HPLC. [ABSTRACT FROM AUTHOR]

In order to contribute to better understanding of the molecular structure–physical property relationship, properties of ferroelectric liquid crystalline materials derived from the lactic acid with the keto group in the molecular core have been studied. These compounds differing only by the length of the chiral and non-chiral alkyl chains exhibit the paraelectric SmA* and the ferroelectric SmC* phases over 150 K broad temperature range down to the room temperature. Temperature dependences of spontaneous polarization, tilt angle, layer spacing, helix pitch length and dielectric permittivity have been compared and discussed for all studied compounds. The effect of the alkyl chains length on mesomorphic properties has been established and discussed in comparison to that of similar materials. [ABSTRACT FROM PUBLISHER]