Thia-bridged tetra- and octa-poly(oxyethylene)-substituted metal free- and Ni(II) phthalocyanines have been synthesized from the corresponding phthalonitrile derivatives in the presence of the anhydrous metal salt (NiCl₂) or a strong organic base. The new compounds have been characterized by elemental analyses, UV/vis, IR, NMR and mass spectra. The mesogenic properties of these new materials were studied by differential scanning calorimetry (DSC), optical microscopy and X-ray investigations. Although octa-substituted phthalocyanine derivatives are liquid all tetra-substituted compounds show a discotic mesophase in an extremely large temperature interval including room temperature. The relationship between the structure of the mesogenic units and the mesogenic behavior is discussed and the influence of the presence of the different heteroatoms in the side chains on mesomorphic properties has been determined.

Synthetic method of compounds 4,4'-bis-(trans-4- alkylcyclohexyl) biphenyl by cross-coupling reaction of arylboric acid and arylbromide in the presence of cetrimonium bromide over nano Ni or Cu catalyst is presented. The reaction is carried out under reflux temperature in THF/H2O for 15 h with yield 60% to approximately 65% for nano nickel and 25% to approximately 30% for nano copper.

The synthetic methods of liquid crystals containing a fluorophenyl or difluorophenyl group and a bicyclohexane or 1,2equalsbicyclo-hexylethane unit were tested. The condensation methods using Mannich salts of (beta) - bromoketones were developed and compared with the coupling method of bicyclohexenones with Grignard reactants or with the thermal decomposition of diazonium salts.

Mesomorphism and photocuring processes of (2- hydroxypropyl)cellulose cinnamate (CYPC) were investigated. The CYPC was synthesized in the course of estrification of (2-hydroxypropyl)cellulose (HPC) by cinnamoyl chloride. The chemical structure of CYPC was confirmed by IR and Raman spectroscopy. The substitution degree of HPC by cinnamoyl ester groups was calculated from ¹H-NMR studies. The thermotropic mesomorphism of CYPC was confirmed by DSC, thermo-optical and X-ray investigations. The thermo-optical behaviors of CYPC tablet obtained under pressure and results of the dielectric spectroscopy investigations were interpreted in terms of the strong hydrophobic effect of the cinnamoyl ester groups. The cycloaddition of the cinnamoyl groups is initiated either by UV radiation or temperature, inside of the hydrophobic aggregates of the cinnamoyl ester groups. The chemical modification of the hydrophobic aggregates in the course of thermo- or photoaddition of the cinnamoyl ester groups slightly changes a molecular movement of the poly(saccharide) main chains of CYPC. However, these crossed aggregates can recover macromolecular orientation of CYPC from the isotropic state via the cooling of sample. These suggest that the hydrophobic aggregates after thermal or photochemical modification shows an anisotropic behavior.

Optically active (see paper for formula) have been synthesized on the base of l-menthon and d-camphor. A possibility to use (alpha) - (beta) -unsaturated ketones in LCD as alloying dopants that are able to induce the helical regulation in the nematic phase is represented. The twisting power and temperature dependence of the induced pitch in the chiral nematic phase of LC compositions cyanobiphenyl and phenylcyclohexane have been investigated. The pitch of the helical chiral dopants basing on d-camphor is reduced when the temperature is increased. Thus they can be used for the reduction of temperature dependence of helical pitch in left-handed twisted dopants on the base of l-menthon.

The mesomorphic behavior of monomesogenic and bismesogenic compounds containing polar oxyethylene chains have been compared with their analogues with nonpolar poly(methylene) tails or spacers. The synthesized compounds were studied by means of DSC, polarized optical microscopy and X-ray diffraction methods. The liquid crystalline properties were considered in respect of compatibility of segments and the type of mesogenic core.

Compounds with the terminal swallow tailed chain have been synthesized. The prepared compounds were studied by thermomicroscopy, differential scanning calorimetry, miscibility and X-ray diffraction methods.

A series of banana-shaped diesters derivated of 3,5-bis-(p- hydroxyphenyl)-1,2;4-oxadiazole and p-alkyloxy- fluoro(difluoro)benzoic acids were synthesized and investigated by optical microscopy and DSC method. The influence of the alkyloxy-substituent lengths and of the F- group position in the molecule on its mesomorphic properties is discussed.

The synthesis and the properties of new liquid crystalline cyclohexene and cyclohexane derivatives and the LC compositions on their base are discussed.

A two-stage method of synthesis of liquid-crystalline diepoxy monomers has been developed. In the first stage, esterification of 4-hydroxyphenyl-4-hydroxybenzoate or 4,4'- biphenol or 4,4'-dihydroxyazobenzene was carried out using 4-penetenoic acid. The resulting olefinic precursors were oxidized with m-chloroperoxybenzoic acid to introduce the epoxy groups. The structure of products was confirmed by FT- IR and ¹H NMR. Examinations on a polarization microscope with a hot plate confirmed the presence of mesomorphic phases in both the precursors and monomers. The phase transition temperatures were in the range of 73.5 (at cooling) to 128.0 degree(s)C for olefinic precursors and in the range 57.1 (at cooling) to 143 degree(s)C for epoxy compounds, as determined by DSC and thermo-optical analysis (TOA).

The synthesis of 4-n-chlorophenyl-4'-n-alkoxythiobenzoates (in short nOSCl) and 4-chlorophenyl-4'-n- alkoxybenzoylthiobenzoates (in short nOOSCl), where n denoted number of carbon atoms in the alkoxy chain of the nOSCl and nOOSCl liquid crystalline compounds have been presented. The substances from nOSCl series show existence of liquid crystals phases in convenient temperature range from uses point of view. The lower homologues possess nematic or nematic and smectic A phases and higher possesses enantiotropic smectic A phase only. The range of smectic A phase changes distinctly upon the elongation of the alkoxy chain. The liquid crystals from the second series, nOOSCl, possess high temperatures of the phase transitions. The temperature ranges of the liquid crystalline phases are distinctly wider for nOOSCl than for nOSCl.

A new synthetic approach for the preparation of two- and three ring liquid crystalline compounds possessing trans,trans-4,4'-dicyclohexyl or trans-4,4'- cyclohexylcyclohexenyl moiety is proposed and developed. The key stage is the Michael type condensation of 2-substituted acetoacetic esters or 4 -substituted benzyl methyl ketones with any precursor of the corresponding vinyl trans-4-alkyl (or aryl) cyclohexyl ketone which gives the corresponding cyclohexenones. Their catalytic hydrogenation in the base media gives saturated trans,trans-cyclohexylcyclohexanones which are liquid crystalline and can be used also as promising intermediates for the preparation of different kinds of other LC compounds.

The synthesis, mesomorphic properties and visible spectra of 4'-substituted alkyl-, alkoxy-, alkylcyclohexyl and alkylcyclohexylethy1-4-isothiocyanatotolanes have been described. Multicomponent mixtures with birefringence higher than 0.4 and low viscosity have been formulated.

The dependence of the temperature of melting and clearing on the alkoxy chains length for 4-alkoxy benzylidene-4'- alkoxyanilines is presented. Conditions at which nematic and smectic C phases are stable are discussed and the entropy effect of clearing is shown.

Crosslinked polycarbosilanes with mesogenic side chains have been prepared by hydrosilylation reaction of poly(1-methyl- 1-silylenemethylene) and the mixture of one and two functional terminal alkenes bearing promesogenic groups. All synthesized networks exhibit SmC* phase in wide temperature ranges. Their LC properties were compared with side chain uncrosslinked polycarbosilanes with the same general chemical structure. In order to make the temperature ranges of generated mesophase wider, the mixtures of crosslinked and uncrosslinked LC polycarbosilanes have been prepared and studied.

Three tin-containing nitroazopolymers with a tin-organic unit were synthesized and characterized by DSC, polarization microscopy, AFM and dielectric measurements. Dielectric measurements prove the existence of three relaxation ranges. No Vogel-Fulcher behavior of the relaxation times were found. At low temperatures only different solid phases and no liquid crystalline exist.

A series of new liquid crystalline cyclic siloxane hexamers was prepared to investigate the influence of the molecular structure of the mesogenic side group on their mesomorphic behavior. Preliminary studies of properties of cyclic siloxanes bearing the various mesogenic side group by means of polarized optical microscopy differential scanning calorimetry and X-Ray diffraction are reported.

Two binary mixtures have been studied of homologues from a series derived from 4-alkoxybiphenyl-4'-carboxylic acid with three chiral centers exhibiting ferroelectric (FE), antiferroelectric (AF) and tilted hexatic phases. One homologue exhibits a re-entrant SmC* (SmC*_re) phase, which is miscible with the SmC* phase. The phase diagrams of the studied mixtures exhibit a close pocket of the SmC*_A phase. The SmC*_re phase is induced even in the mixtures composed from homologues without this phase. Dielectric spectroscopy reveals the Goldstone mode in both ferroelectric SmC* and the SmC*_re phases, this mode being stronger when increasing concentration of the antiferroelectric homologue: In the SmC*_A phase a relaxation mode is detected with the relaxation frequency three orders higher, which exhibits critical slowing down when approaching the SmC*_re phase. This mode, which can be attributed to the anti-phase mode is responsible for the appearance of the SmC*_re phase. In mixtures exhibiting the SmC*_A phase a helix twist inversion occurs in the vicinity of the low temperature border of the AF phase.

In this work, the use of antiferroelectric and V-shape liquid crystals for video projection using LCOS microdisplays has been explored. Antiferroelectric gray levels arise from a double symmetric hysteresis loop that can be stabilized by a constant holding voltage, thus an active matrix is not strictly required in this case. If used, then the voltage levels and the waveform must be adjusted to fulfill the voltage limitations dictated by the matrix. V-shape materials lac,k hysteresis; therefore the active matrix is mandatory to stabilize the levels. Voltage limitations, however, are less restrictive in this case, since V-shape smectics require just a few volts for full switching.

We studied the change in polarization direction during field reversal in binary mixtures possessing antiferroelectric phase. Due to the coupling of the electric field with the spontaneous polarization of each smectic layer, the transition from antiferroelectric to the ferroelectric phase was induced. This transition was accompanied by changes in optical properties. Both three-state and V-shaped switching was observed. After removing the field, the sample transformed back to the antiferroelectric state. We have found that in some cases, the kinetics of this transition was very slow its time constant ranged from minutes to days, depending on temperature. In the same mixtures, we observed a large thermal hysteresis of the phase transition between the ferroelectric and antiferroelectric phases. We argue that all three phenomena: V-shaped antiferroelectric interactions acting between smectic layers are of comparable strength. We compare our results with the existing models of V-shaped switching and propose a modification of the models.

The V-shaped transmission-voltage characteristics in FLC have been explained by the existence of a splayed state, caused by strong polar interaction with the alignment layers. Both simulation results and analytical calculations have been used to confirm this statement. The conditions that guarantee V-shaped characteristics have been described. There is no consensus on whether V-shaped characteristics can exist in AFLC. In tri-state switching the AFLC will be in the so-called ferroelectric up- (or down-) state FU (FD) for sufficiently high applied positive (negative) voltage. By means of the uniform-(phi) theory it has been shown that if V decreases to zero, one first follows the symmetrical up- (down-) state SU (SD), and then switches back to the normal alternating state so called antiferroelectric state AF. In this article we investigate switching from a strong positive voltage to zero and check under which conditions one ends up in a special alternating state SA, with both polarizations parallel to the glass surfaces, instead of in the normal alternating state, with both polarizations perpendicular to the glass surfaces. The first case guarantees V-shaped switching in AFLC, the second case leads to tri-stable switching. The simulation program is based on implicit iteration and on the Newton-Raphson linearization method. Several simulation results will be shown and discussed. They confirm that V-shaped switching occurs in AFLC under approximately the same conditions as for FLC, i.e. with strong interactions with the alignment layers.

The spectroscopic technique using the Fabry-Perot [FPSS] etalon coupled with a spectrometer has been used to determine the mesophase transition temperatures of the samples (1) MHPB(H)PBC (2) MHPB(Cl)PBC. Earlier FPSS work on the sample MHPOBC(R) is also substantiated here with results from Differential Scanning Calorimetery [DSC] and Polarization Microscopy Studies [PMS]. A comparison of the results obtained with those of DSC clearly indicates the success of the FPSS technique in determining the transition temperatures of the above samples belonging to the FLCs and AFLCs groups. The photographs of the textures using PMS also support the above results. This novel technique has led to the detection of new mesophase transitions in addition to those reported by DSC and PMS. These new findings are also corroborated by the analysis of the thermal runs using DSC and the textures from PMS.

Chiral aryl esters of 4-alkyl-3-chlorobiphenyl-4'-carboxylic and 4-(6-alkylcyclohex-2-enonoyl-3)benzoic acids have been synthesized. The phase transition temperatures and V-shaped SmC* switching of the prepared compounds are discussed.

Two series of ferroelectric liquid crystalline materials, non-substituted and containing a methoxy lateral group at the aromatic ring of the molecular core have been investigated by dielectric relaxation spectroscopy in the range from 1 Hz to 1 MHz. All compounds exhibit chiral SmC* phase. A low temperature ferroelectric phase, consisting of the ordinary SmC* phase and a crystalline phase, was detected in three of the investigated compounds. The frequency dispersion reveals two modes (denoted as mode 1 and mode 2) detected in both ferroelectric phases. The analysis of the frequency dispersion of the complex permittivity provides relaxation frequency and dielectric strength of these modes. In the SmC* phase, high frequency mode 1 is the Goldstone mode. Low frequency mode 2 is attributed to a non-homogenous distribution of ionic space charge, which is localized near the surfaces. The values of P_s in the low temperature ferroelectric phase are lower than in the ordinary SmC* phase for the methoxy substituted compounds but shows no anomaly for the non-substituted material.

New liquid crystalline substance has been studied by means of frequency domain dielectric spectroscopy (FDDS) and electro-optic methods. Typical soft mode is visible in paraelectric SmA* phase. Temperature dependencies of dielectric increment and critical frequencies in SmC_sub* are more complicated what suggests existing of SmC_(alpha )* phase. There is no evidence of the Goldstone mode in the monotropic SmC_(alpha )* phase what supports the idea of its antiferroelectric nature. It is confirmed by measurements of spontaneous polarization by the reversal current method. Two peaks appear on the opposite sides of the zero field. The temperature dependence of spontaneous polarization as well as FDDS measurements show that transition between the SmC_(alpha )* and paraelectric SmA* phases seems to be a first order transition.

We present a study of the influence of new chiral additives 2 and 3 on phase transition and molecular parameters of binary mixtures of cholesteryl enantate and cholesteryl laurate. The addition of these compounds to the binary mixture of the cholesteryl enantate and cholesteryl laurate results in shift of the cholesteric smectic phase transition towards the direction of lower temperatures, about 10 - 12 degree(s)C. Using X-ray diffraction on the crystalline powder of unoriented samples we have determined the molecular parameters: the thickness of smectic and cholesteric layers (d) and the value of molecular parameter average distance between the long axes of neighboring molecules (D). The calculation of the value of molecular parameters d and D, indicates decrease of the thickness and packing density of the molecules of smectic layers, in Mix 1 and Mix 2, compared to 50 - 50% mixture.

New chiral ethers with the 2-arylidene-p-menthan-3-one skeleton have been investigated as components of the induced cholesteric (N*) systems based on 4-pentyl-4'-cyanobiphenyl. A rather high helical twisting power in combination with the weak temperature dependence of the induced helical pitch has been demonstrated for these compounds. The chiral compounds studied containing the terminal oxyalkyl group have been found to increase the thermal stability of N* mesophase. The experimental results obtained have been interpreted basing on the conformational analysis by semi-empirical AM1 and PM3 methods. The significant predominance of gauche-conformers of bent shape for benzyloxy fragment has been found to be the major factor causing the distinctions in the behavior of these chiral dopants in LC host system with respect to their linear analogs containing no ether linking group. The shift of the conformational equilibrium of the chiral ethers towards more anisometric conformers provoked by the orienting effect of the liquid crysalline environment has been assumed.

Some1R,4R-2-(4-phenylbenzylidene)-p-methane-3-one derivatives containing the ether or ester linking group between benzene rings of the arylidene fragment have been studied as chiral dopants in ferroelectric liquid crystal systems based on the eutectic mixture (1:1) of two phenylbenzoate derivatives (see paper for formula) The ferroelectric properties of these compositions (spontaneous polarization, rotation, viscosity, smectic tilt angle as well as quantitative characteristics of their concentration dependences) were compared with those for systems including chiral dopants containing no linking group. Ferroelectric parameters of the induced ferroelectric compositions studied have been shown to depend essentially on the presence of the linking group between benzene rings and its nature as well as on the number of the benzene rings in the rigid molecular core of the chiral dopants used. For all ferroelectric liquid crystal systems studied, the influence of the chiral dopants on the thermal stability of N*, SmA and SmC* mesophases has been quantified. The influence of the linking group nature in the dopant molecules on the characteristics of the systems studied is discussed taking into account results of the conformational analysis carried out by the semi-empirical AM1 and PM3 methods.

We investigated V-shaped switching in ferroelectric liquid crystal (FLC) mixture. Using standard, symmetrical preparation of the LC cells we obtained texture called 'two- domain texture.' In our opinion an appearance of this texture is related to surface electroclinic effect. We proposed to use non-symmetrical treatment of alignment surfaces. Textures obtained in this way are much uniform than the previous ones. The paper presents the results of theoretical investigations and experimental work.

A new relaxation process in a nanoconfined ferroelectric liquid crystal (FLC) with high spontaneous polarization and short helical pitch is presented. In the cylindrical geometry of Anopore membranes, a collective dynamic process in the MHz region appears in the SmC* phase, instead of the phason (Goldstone) bulk relaxation. The relaxation frequency is temperature independent (except near the SmA/SmC* phase transition where an increase is observed). The origin of the process is discussed, the most consistent explanation assumes a relaxation of flexoelectric polarization near the splayed regions at the pore walls.

The aim of our work was precise dielectric permittivity measurements of compound: (See paper for formula) Results of spontaneous polarization, tilt angle in the SmC* phase and first dielectric permittivity measurements of all phases of this compound were presented by us. The phase transition to SmC* phase is characterized by strong maximum for low frequencies and minimum for high frequencies of dielectric responses. Thus in 118 degree(s)C for our compound one can see phase transition to SmC* phase². From the linear temperature dependences of relaxation frequency f_R and the inverse dielectric strength 1/Δε_{(perpendicular}) obtained by fitting experimental values ε' and ε" to Cole-Cole equation, the SmC_(α )* (in the narrow temperature regions) is detected due to the change of the slope. The relaxation process observed in the SmC_(α )* phase is strongly modified under bias, thus it is probably connected with the helicity of SmC_(α )* e.g. ferroelectric-like structure of this phase.

Dielectric investigations of ferroelectric liquid crystals at low frequency range enabled to detect two kinds of collective molecular motions: the Goldstone mode and the soft mode. The mixture of recently synthesized ferroelectric and antiferroelectric liquid crystals with relatively broad temperature range of SmC* and SmC*_A phase was chosen for investigation of dielectric loss processes.

This paper discusses the role of dipole-dipole interactions in determining the dielectric response of nematic liquid crystals. The theory of dipole-dipole correlation in liquid crystals is reviewed and results of computer simulations of model dipolar mesogens are commented upon. Dielectric measurements are reported for a variety of nematic liquid crystals of differing molecular structures. It is found that dipole association is dependent on the molecular shape and the direction of the dipole moment within the molecule. Experimental results, theory and simulations are all in accord that rod-like molecules with longitudinal dipoles tend to self-organize with local anti-ferroelectric order. If the dipole direction is changed to be perpendicular to the long molecular axis, then there is local ferroelectric order. Disc-like molecules are predicted to exhibit local ferroelectric order if the dipole is along the axis of the disc, but may show anti-ferroelectric order if the dipole is in the plane of the disc. Introduction of flexibility into the molecular structure can have a large effect on the dielectric properties. This is illustrated for dimeric liquid crystals, and the results are interpreted in terms of a model of interconverting conformers having different molecular shapes and dipole moments.

The aim of the paper is to emphasize the importance of mathematics for understanding of physical phenomena. Vibrations of smectic films and facetting of cubic liquid crystals are the two topics of the liquid crystal physics used as examples. The case of facetting of the Pn3m cubic phase is illustrated by new observations.

Dielectric results of three bent shaped compounds are presented. An increase of the static dielectric constant in the isotropic phase by approaching the I-B₂ transition is seen in the first sample. The second sample shows the polymorphism I-SmA-SmC-B₂. Down to the SmC phase only the reorientation about the long molecular axis without a step in the relaxation time is observed. In the B₂ phase an additional low frequency relaxation is detected resulting from the antiferroelectric structure. The interesting feature is the increase of the dielectric increment (Delta) ₂ of the high frequency mechanism with decreasing temperature: Starting from about 2.5 in the SmA phase (Delta) ₂ increases continuously and reaches at the transition into the B₂ phase values of about 40. This result points to the step by step increase of the ferroelectric short range order within the SmA and specially the SmC phases. The last sample confirms this result for the polymorphism I-SmA-C_PA, with one exception the low frequency process is missing.

An application of liquid crystalline materials as a model materials for the use in dielectric spectroscopy of the artificial biological materials and the tissues is discussed. It is shown that an application of the standard electrochemical concepts may break in the case of liquid crystalline materials as well as biological materials. The presence of space charge regions as well as electrical non- linearities of the sample may suggest some special possibility of the time domain technique application.

The periodic deformations of planar nematic (1), planar twisted nematic (2), and hybrid aligned nematic (3) layers, were analyzed numerically. In the cases (1) and (2), the periodic deformations induced by magnetic field under strong anchoring conditions, were taken into account. In the case (3), the so called splay stripes, which arise spontaneously under the weak anchoring conditions, were considered. In each of these geometries, two different types of periodic deformations were found. For all deformations, the director distributions were calculated. The ranges of material and layer parameters, for which the periodic deformations occurred, were determined. The following features, common for most of the deformations, were found: (1) wide regions with nearly homogeneous deformation exist in two halves of a stripe in strongly deformed layers; (2) the spatial period of the deformations diverges to infinity with variation of suitable parameter (e.g. field strength, twist angle, anchoring energy etc.); (3) above critical values of parameters, the nearly homogeneous regions spread over the whole layer and the periodic deformations are replaced by homogeneous distortions.

In this paper we investigate three one-dimensional ion transport simulation algorithms and compare the results. The ion transport algorithms are incorporated in a one- dimensional Liquid Crystal Display (LCD) model that calculates the director orientation and the influence of ions on the electrical field. The aim is to improve calculation speed and accuracy. The first algorithm is the traditional explicit forward method using finite differences. The second algorithm is based on the first, but it assumes an exponential variation, instead of a constant ion concentration in each interval. The third is Monte Carlo based. It does not use any intervals but calculates drift for individual ions and treats diffusion as a random walk. We investigated the frontiers of stability and speed with respect to the accuracy, by varying the time steps and the number of intervals. The main conclusion of our work is that the calculation speed can be improved by using the new algorithms without loss of accuracy. The exponential algorithm proves to be very helpful in the simulation in the case of ions piling up near the alignment layer. The Monte Carlo algorithm is the most appropriate and at the same time a promising candidate for extension to two-dimensional simulations.

Surface pressure-mean molecular area isotherms of Langmuir films of some liquid crystals with CN or --NCS terminal group as well as of their binary mixtures have been recorded. It was found that only the liquid crystals which molecules have CN group are able to form a stable monolayer at the air-water interface. Information about the molecular organization and intermolecular interaction in two dimensional layer has been obtained. Moreover, the miscibility or phase separation of two components in the mixtures of various compositions has been determined by using excess area criterion and surface phase rule.

The spherulite crystallization of a two-dimensional sample was simulated by the computer for various types of temperature instabilities. The simulation provided the data that enable to recognize the kind of instability basing on the image of crystallized sample.

The orientation of the molecular tilt plane and the bond net of several hexatic liquid crystals can be characterized by phase angles neglecting disturbances of the order parameter amplitudes. We investigate the dielectric response due to fluctuations of the phase angles. For a thin cell with unwound director helix two relaxation modes are predicted.

Liquid crystal filled polymer structures provide switchable optical devices at low cost and with low driving voltages. One such device is a switchable optical grating, current models of these do not fully explain the effects seen within the devices that have been constructed. A new modeling technique has been implemented to better understand these. A comparison of the use of the Oseen-Frank and Landau-De Gennes free energy equations is given. Data from an experimental device is compared to that from simulation and it is shown that the simulation provides both similar results and an aid to understanding the real device.

The value of (alpha) _(parallel) and (alpha) _{(perpendicular}) of liquid crystal molecule can be calculated from refractive indices, density and k_A. It is well known that the refractive indices are a function of temperature and light wave length. In this article we verified the influence of the light wave length on the values of polarizability tensor components (alpha) _(parallel), (alpha) _{(perpendicular}), of polarizability anisotropy ((alpha) _(parallel) - (alpha) _{(perpendicular})) and of the order parameter S of liquid crystal molecules. The values of order parameter S obtained for CB 6 liquid crystal are identical for all light wave length.

According to classical method polyimides were obtained in two-step polycondensation process via 10% solutions of poly(amic acid)s in dimethylformamide (DMF). Poly(amic acid)s were synthesized from chosen tetracarboxylic acids dianhydrides: pyromellitic (PMDA), 4,4'- (hexafluoroisopropylidene)diphthalic (6FDA), 4,4'- oxydiphthalic (ODPA) and aromatic diamines: 4,4'- oxydianiline (ODA), 1,4-phenylenediamine (PPD), 4,4'- ethylenedianiline (DAB), 4,4'-diaminodiphenylmethane (MDA), 4-methyl-1,3-phenylenediamine (MMPD) and 2,3,5,6- tetramethyl-1,4-phenylenediamine (DAD) in the first step of this reaction. The indium tin oxide (ITO)-glass plates or glass plates were spin-coated with the poly(amic acid)s solutions and dried. The polyimide layers were prepared by gradual heating in various temperatures (100 degree(s)C, 150 degree(s)C, 180 degree(s)C, 200 degree(s)C, 220 degree(s)C and 250 degree(s)C). The degree of imidization was estimated by means of IR spectroscopy. Obtained PI layers were mechanically modified by rubbing. Three various rubbing materials were used: cotton, silk and chamois leather. Surface free energy and its components of polymer layers were evaluated on the basis of their wet ability by standard liquids (diiodomethane, 1- bromonaphthalene, formamide, ethylene glycol, water). It was found that decrease of intensity of rubbing process yields to increase of contact angle for each of rubbing materials. Polyimide layers rubbed with chamois leather were characterized by the best wet ability. The rubbing process increase surface free energy of tested polyimide films.

We investigated the dielectric dispersion of two homologous series: n-alcylcyanobiphenyls (7CB, 8CB) and n-alcyloxy- cyanobiphenyls (70CB, 80CB) both in the isotropic phase and crystal states in the frequency range from 100 MHz to 1000 MHz. For each substance the dielectric spectra can well be described by the Debye equation with one relaxation time. It has been established that additional peaks at about 170, 280, 360, 450, 550 and 600 MHz exist in all spectra. Comparative analysis of the dielectric spectra has shown when the oxygen is disposed in the mesogenic core of the molecule his effect on frequencies of the peaks is absent. But in n-alcyloxy-cyanobiphenyl substances the peaks splitting and increasing in their strength are observed. The dispersion spectra were interpreted as a sum of Debye relaxation process and of resonance type.

The escaped disclinations arising in capillary tubes or in Schlieren texture, were analyzed numerically. The flexoelectric properties of the nematic liquid crystal and the presence of the ionic space charge were taken into account. The splay and bend deformations, occurring in these systems, led to the flexoelectric polarization which in turn gave rise to the potential differences and charge redistribution in the samples. The director orientation angle, the electric field strength and the space charge density were calculated as functions of radial coordinate by solving the torques equation and Poisson equation. For example, in the capillary with homeotropic boundary conditions, the effective positive space charge occupied the relatively large central regions, whereas the negative space charge gathered at the wall. In the Schlieren textures, the positive space charge was accumulated on the disclination lines and in their close neighborhood. The negative charge was removed from this region and spread over the rest of the layer. In the highly pure nematics, the radial electric field of order 10⁴ V/m arose in central parts of the capillaries and in vicinity of the disclinations in the Schlieren texture. The concentration of ions accumulated on the disclination lines in the Schlieren texture of well purified nematic exceeded the average bulk concentration of ionic impurities by nearly two orders of magnitude.

The comprehension of the mechanism of alignment of a liquid crystal by a rubbed polymer layer is a current interest from a fundamental point of view but also in regards to applications. To understand the mechanism of alignment it is necessary to clarify how the liquid crystal is oriented near a surface. A nematic liquid crystal (LC) has a longer a uniaxial symmetry near a rubbed polymer surface but exhibits a biaxial orientation. We probed the thickness dependence of the orientation of a LC using Fourier Transform Infrared Spectroscopy. By this method it can be shown that the order parameter is lower near the surface than in the bulk and that the symmetry of a nematic liquid crystal close to the surface of the alignment layer is not longer uniaxial.

In this paper relation between the diffraction efficiency in LC dye doped cell in two wave mixing system and the applied voltage parameters had been described. The goal of this work was increase of diffraction efficiency using low frequency AC voltage. The LC cells used in the experiments were filled with pure and dye-doped liquid crystal mixtures. In this system we obtained diffraction efficiency increasing about five to eight times.

Polyimides were prepared in the classical two-step method via poly(amic acids). Poly(amic acids) were obtained from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'- (hexafluoroisopropylidene)diphthalic anhydride (6FDA), pyromellitic dianhydride (PMDA), 3,3',4,4'- diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'- oxydiphthalic anhydride (ODPA) and amines 4,4'-oxydianiline (ODA), 1,3-phenylenediamine (MPD), 1,4-phenylenediamine (PPD), 4,4'-diaminodiphenylmethane (MDA), 4,4'- ethylenedianiline (DAB), 2,4,6-trimethyl-1,3- phenylenediamine (TMPD), 4-methyl-1,3-phenylenediamine (MMPD) and 2,3,5,6-tetramethyl-1,4-phenylenediamine (DAD) in dimethylformamide. The indium tin oxide (ITO)-glass plates were spin-coated with the poly(amic acids) solutions and dried. A thermal imidization process was then carried out at 250 degree(s)C for 4 h. In this study the anchoring energies of 6CHBT molecules were evaluated on rubbing aligning layers of PI films. The polar anchoring energy coefficient was determined by wedge cell method. The surface free energy and its components of polyimide layers were determined by measuring the contact angles of water, ethylene glycol, formamide and diiodomethane drops on the rubbing polymer surfaces. The Lifshitz-van der Waals and acidic-basic components of surface free energies were found from van Oss equation.

The practical application of the composite method of the determination of nematic liquid crystal material parameters (namely the splay and bend elastic constants, the anisotropy of diamagnetic susceptibility and the boundary tilt angle) is presented. The description of phenomena is based on the Ericksen-Leslie theory of nematics. The director field value at the nematics cell boundaries is described as a function of the torque transmitted from the deformed bulk, modeling the coupling between a nematics and a substrate. The method is based on approximate solving the coefficient inverse problem. The applied procedure of the determination of material parameters may be divided into three stages. The first one was the preparation of flat-parallel nematics cells, made of the same nematics and with the same treatment of the glass plate surfaces. The second one was the measurements of the optical response of the cells influenced by an external electric field (a voltage). Such cell characteristics contain information about the unknown magnitudes of material parameters. The final stage was the determination of the magnitudes of liquid crystal material parameters as solutions of coefficient inverse problems with measured cell characteristics as input data. The method was applied to study a system nematics PCB - polyimide PI10.

A wedge cell of the wedge angle of order of few milliradians was used to measure the threshold and saturation voltages for the Freedericksz transition induced by an electric field. The nematic liquid crystal filling the cell was of planar orientation enforced by the treatment of the flat boundary plates. A system of interference fringes appeared in the cell placed in normally incident light between an analyzer and a polarizer. In the vicinity of each fringe the cell can be considered as a flat-parallel one and hence it is equivalent to the system of flat cells of different precisely determined thickness. Both the characteristic voltages were interpreted as the eigenvalues of the operator of the second derivative corresponding to the boundary eigenvalue problems with different boundaries; the interaction between the nematics and the substrate was described by the Rapini-Papoular formula. The resulting formulae were used to determine the polar anchoring energy coefficient after the measured characteristic voltages. The method was applied to characterize the coupling between 6CHBT nematic liquid crystal and the substrates made of poly(siloxanoimide), polyvinyl alcohol, indium-tin oxide and silicon oxide.

A series of new liquid crystalline divinyl and diepoxy monomers of different length of stiff segments, were synthesized. Relaxation phenomena in one of these compounds were investigated at different temperatures using Solartron 1260 Impedance Analyzer with Chelsea Dielectric Interface in the frequency range 10^-2 Hz - 1 MHz. The liquid crystalline material was introduced between two parallel glass plates covered with conducting ITO layer and polyimide thin film with anti-parallel rubbing. The microscope observations have revealed a planar texture in this kind of sample. In order to find the influence of the polyimide thin film on the texture the investigations of a sample with out the polyimide film were also carried out. In this case the homeotropic structure was detected at zero external electric field. Three loss peaks were detected in the investigated frequency range. The dielectric response is sensitive to the phase transitions observed in this material. The temperatures of the phase transitions determined from the dielectric study are in a reasonable agreement with those obtained from thermo-optical analysis.

The direct measurement of the refraction index profile in the nematic layer (NL) creates possibility to verify and exploit the non-linear solution of the Ericksen-Leslie equation (E-L). It has been done for NL of 6 CHBT tuned in wide range of external voltage. The symmetrical case of the director field distribution has been analyzed. The way for local values of the electric field estimation inside the lc layer is discussed.

Results of the polymorphism investigation of liquid crystalline mixtures made of compounds belonging to the thioestrs homologous series: nOS5 and nOSCl and alkoxybenzoic acid (nOB) are presented. The principal component of the mixtures was 4-n-pentylphenyl-4'-n- heptyloxythiobenzoate (7OS5) and the following mixture: 7OS5/8OSCl and 7OS5/6OB were prepared. Also the mesomorphic properties of p-n-alkoxybenzoic acid with alkyl chains of length n equals 4 to 16 have been studies. The transition temperatures of all compounds and the binary mixtures were determined by means of DSC calorimetry and polarizing microscopy methods. Unidentified smectic phase for 8OB and 10OB were observed during heating and cooling processes. For all concentrations of binary mixtures linear dependence of T_cl was observed.

The properties are described of the smectic A₁ phase occurring in two homologous series with the terminal group NCS: nDBT and nTPCHB. The results of miscibility studies of the smectic phases of these compounds with the smectic A₁ and A_d phases of cyanocompounds nOBCAB are described. It has been shown that the properties of the smectic phases of compounds nDBT and nTPCHB are different, so these phases are treated as two different subtypes of smectic A₁ phase.

We report observation of the dynamic enhancement of photorefractive effect in dye-doped nematic liquid crystal in the presence of an applied ac electric field. The multi- wave mixing efficiency in a planar cell with photoconductive orienting layers has been increased by two orders.

Liquid crystals are very important anisotropic materials in modern optoelectronics. Among other unique properties, liquid crystals have giant optical nonlinearity due to the reorientational effect. Unfortunately, the response time in reorientational phenomena is large and its determination and reducing is very important issue. In this work the measurements of time of increasing the nonlinear reorientation in nematic layer are presented.

Mixtures of the first six members of homologous series 4,4'- di-n-alcoxyazoxybenzenes were investigated by DSC and HSM (heat stage microscopy) methods. A solid crystal (SC) form of the third member (C₃) of the series is found which is virtual for the pure substance and is real for mixtures with the homologous. It is shown that a type of admixture C_n changes relative stability of SC forms K_v, K₁, K₂ of the pure C₃. A eutectic manifestation of mixture (K₁ + K₂) is found. Four SC forms of C₃ have an equal enthalpy of transitions to a melt. Melting in the mesophase is accompanied by transformations of crystal structures.

Realization of complex high information density LCDs and systematic optimization of their electro-optical and ergonomic performance would not be possible in the required time-frame without reliable numerical modeling of the electro-optical performance of such display devices. In this paper we outline the history of numerical LDC modeling starting with Berreman and van Doorn, finally arriving at modern state-of-the-art LCD-modeling in two and three dimensions. Numerical modeling of LCDs is carried out in two steps: first, the effect of the electrical field on the orientation of the liquid crystalline alignment has to be evaluated before the corresponding optical properties can be computed. Starting from LC-elasticity theory we present suitable numerical methods for computing various states of LC-deformation (stable, metastable, bistable, etc.) in one- dimensional problems Light propagation in layered anisotropic absorbing media is evaluated with methods that are based on Maxwell's equations (Berreman 4 X 4-matrix approach). This approach can be simplified to yield methods with reduced computing time and sufficient accuracy for many problems (e.g. extended Jones 2 X 2-matrix formalism). A finite element method with automatic mesh generation and refinement for computing accurate solutions in two- dimensional problems is presented and its application illustrated with examples (e.g. IPS-effect, VAN-cells, etc.). In two- and three-dimensional problems, i.e. in cells with lateral dimensions comparable to the cell thickness, a variety of different director configurations are possible for a given geometry and electrical driving and addressing, making the modeling more complicated. Moreover, local defects can occur, which should also be considered in the simulation. Suitable approaches for the director field calculation, i.e. the vector and the tensor approach, are discussed. The complexity of the problem increases considerably when a third dimension is added, e.g. the geometry of the problem has to be defined in three dimensions together with the respective boundary conditions (anchoring geometry and elasticity) and electrodes. If strong deformations or even distortions are present in the orientation of the LC-layer, the applicability of known one- dimensional approaches for computing the optical properties must be checked and new approaches eventually have to be developed. The third dimension prohibits the use of some standard methods (e.g. FDTD), solely because of the enormous memory requirements and the long calculation times. Other approaches are presented and discussed.

Electro-optics of smectic liquid crystals has been drawing an increasing interest, especially for new classes of compounds, such as metal alkanoates, which manifest as thermotropic as lyotropic smectic mesophases. In the present work electric and electro-optic properties were studied of pure and dye-doped (polymethine dye) potassium kaproate, a water mixture of which is forming a lyotropic Sm A type liquid crystalline phase at room temperature. As follows from experimental data, for frequencies - f < 3 X 10⁴ Hz, dispersion of the components of complex dielectric permittivity ε' and ε" is observed. Appropriate relaxation process is described by the Debye equation. On the basis of the analysis of frequency dependencies of (epsilon) ', (epsilon)" for the frequencies f > 3 X 10⁴ Hz the conductivity of samples on an alternating current was found. The introduction of dye in ionic lyotropic liquid crystals (ILLC) results in an increase of conductivity (by 1,5 times) and reduction of relaxation time. The bleaching of the dye in ILLC under the action of a direct voltage (U > 5V) was observed. The mechanism explaining threshold character of such process was proposed.

In recent years Thermochromic Liquid Crystals (TLC) have been successfully used in non-intrusive heat transfer and fluid mechanics studies. Thin coatings of TLC's at surfaces is utilized to obtain detailed heat transfer data of steady or transient process. Application of TLC tracers allows instantaneous measurement of the temperature and velocity fields for two-dimensional cross-section of flow. Computerized flow visualization techniques allow automatic quantification of temperature of the analyzed surface or the visualized flow cross-section. Here we describe our experience in applying the method to selected problems studied in our laboratory. They include modeling flow configurations in the differentially heated inclined cavity with vertical temperature gradient simulating up-slope flow as well as thermal convection under freezing surface. The main aim of these experimental models is to generate reliable experimental database on velocity and temperature fields for specific flow. The methods are based on computerized true-color analysis of digital images for temperature measurements and modified Particle Image Velocimetry and Thermometry (PIVT) used to obtain the flow field velocity.

The analysis of the tuned, liquid crystalline Fabry-Perot interferometer (FPTI) has been done by means of 4 X 4 matrix. Wide-angle incidence has been analyzed in terms of Trollinger-Chipman correction for extraordinary wave. Results have been applied to determine constraints in the design of the monochromatic tuned FPTI. Main features of the FPTI device and liquid crystal determining FPTI parameters has been described in detail. Especially attention has been paid on dispersion of the LC' refraction indices as a factor of spectral FPFI' properties.

Nowadays, the car driver are faced with a rapidly increasing flood of information. In addition to established information systems (car radio, vehicle monitoring, mobile phones), high class vehicles feature navigation systems almost as standard. In the current decade, driver assistance and collision avoidance systems will appear in vehicles. Hence, there is an increasing demand for supplying the driver with more information that help him to drive safer and more economical. The price decline in the computer market and the availability of powerful graphic hard- and software concepts make it possible to enhance the classical functions of the instrument board to an interactive multifunctional information panel - an interface between information systems of the car and the driver. Therefore, the question of additional visual and cognitive stress, and a possible distraction of the driver by the large amount of information, and its complexity becomes predominant. Reconfigurable instruments, based on a microprocessor controlled active matrix color display, provide a powerful alternative to the usual mechanical/electromechanical instrument clusters in vehicles. They will help to strengthen passive safety, they adapt to user and situation requirements, and they are easy to install, to configure, and to maintain. Reconfigurable instruments in future cars will have a high impact on traffic since they can provide the driver with much more information, presenting it in a way that is flexibly matched to the importance of particular data and to the ergonomic properties of the driver. The functions are manifold and span from classical driver information like speed to navigation prompts and ultimately to video and multimedia access.

In the present work we focused our attention on studies of PVK:TNF hybrid polymer liquid crystal panels under short pulse laser illumination conditions. The diffraction gratings in a LC panel were induced by crossed beams generated by doubled in frequency Nd:YAG laser ((lambda) equals 532 nm) delivering pulses of 20 ps duration. So induced gratings were read by a cw laser radiation coming from a weak power He-Ne laser working at (lambda) equals 632.8 nm. The temporal evolution of intensity of first order diffraction measured in PVK:TNF hybrid liquid crystal panels shows many interesting features and complexity dependent on various experimental conditions. The substantial diffraction is observed already in time less than 1 ms after the pulse and the grating decay is completed within hundreds of milliseconds. At least three different steps of grating build-up can be distinguished which depend in various ways on the experimental conditions. A tentative mechanism of the observed responses is discussed in connection with the photoconductive properties of polymeric layers and the optical and electrical properties of the used liquid crystal E-7 (Merck).

A system LC-waveguide may be applied in different devices for physical values registration, and optical signal controlling devices. It is actual to use a planar waveguide in combination with peculiarity of liquid crystal materials that are characterized by a high sensitivity to physical values external influence liquid crystal materials. At present time waveguides are widely used as elements for signals processing and transmission in optical systems, that are realized on different optical effects. The using of planar waveguide as backplane of LC cell alleviate orientation process of liquid crystal layer in contrast to fiber waveguide.

Recently, there have been shown that in planar liquid crystalline waveguides light beams can form spatial soliton due to the reorientational nonlinearity. Such self-trapped beams require only a few tens of mW of light power and their stability is controlled by state of the light polarization. In this paper, the collisions of previously observed solitons are analyzed theoretically. Obtained results show that analyzed self-trapped beams became unstable due to the interaction with other light beams.

In this paper we present experimental results on the influence of an external light on phase grating recording process in nematic liquid crystal cell with a photoconducting polymeric layer (PVK doped with TNF). Depending on voltage applied to the cell the external light can amplify on attenuate the diffracted into first order light power measured in degenerate two-wave mixing experiment. From the time delay between the opening of the external light and the moment of diffraction signal change we deduce an information about the effective charge carriers mobilities in PVK:TNF polymeric layer. We also discuss and present simple explanation of the observed effect.

This paper contains the results of theoretical considerations about light propagation through the real TN display working in reflective and negative mode. This mode provides us with a possibility to obtain a color image. We have done mathematical and numerical analyses of a propagation of light wave through LC displays with antireflective layer, glass planes, conductive layers, liquid crystal layer and polarizers. We have taken into account real conditions of a display operation, i.e. spectral properties of all components, optical anisotropic and dichroic properties of LC layer, reflections from all phase borders and also spectral characteristics of light source and sensitivity of human eye.

The paper presents a new approach to structural investigations of elliptical-core liquid crystal fibers (ECLCFs) by using the interferometric method. The method enables to confirm envisaged molecular distribution within the elliptical core previously observed in polarimetric configuration.

A visualization technique is used to measure the heat transfer to a plane surface with obstacles. Liquid crystal coated on a mylar sheet is used to locate isotherms on a cooled plate. The isotherms on the plate surface are recorded by JVC-camera and true-color image processing system. Experimental procedure cover full-field flow patterns in heat exchanger element (flat plate with discs in-line, staggered and with vortex generators) describing local heat transfer coefficient and Nusselt number on the surface.

The particular family of liquid crystalline filters is presented. Their basis application is multiresolution image analysis (wavelet transform). That filter creates polarized beam of light, which constitutes the Haar wavelet. Simulation of such a filter by means of 4 X 4 matrix is presented as well as experimental results. The picture of the filter in polarized light is shown below in Fig. 2. In cooperation with phase shifter the polarization of the light beam may be rotated in the filter to extract image's features.

Photorefractive properties and possibility of guest-host effect application for real-time holography have been described. Isothiocyanate nematic liquid mixtures with positive dielectric anisotropy as hosts while antraquinone dyes as guests were used. In dye-doped nematic liquid crystals high diffraction efficiency approaching 20% were obtained. Fast optical grating formation with a time constant (tau) of a few ms have been observed. The dependence of grating formation on strength of applied dc and low frequency of ac electric field, configuration of light polarization and nematic director orientation were reported.

The possibility of diffraction pattern generation in LC (Liquid Crystal) cells working as a dynamic write-read media was proven. Recording of holographic gratings formed by interfered He-Ne laser beams onto LC-cells with pure and dye-doped mixture have been investigated. The possibility of optoelectronic reconstruction of digitally stored microinterferograms allow us to adopt them in multimedia application. The hologram of virtual or real object was reconstructed by coherent illumination of optically addressed spatial light modulator (OASLM) containing holographic grating. The results obtained from LC cells of standard twisted nematic type were examined. As a result of examination of physical properties of nematic-type liquid crystal mixtures, new method of realization of LC cells were proposed. The experimental results of replacing TN cells with polivinylcarbazole (PVK) photosensitive layer cells have been discussed.

The liquid crystal display dashboard for polish gliders PW-5 and PW-6 have been presented. The measuring flight parameters system and electronic scheme of the glider have been proposed, developed and tested. Laboratory investigations of the board flight parameters and their compatibility with standards have been described.

Dynamic properties of some polymer nematics were investigated by Freedericksz transition methods in a magnetic field. The linear aromatic polyester, comblike combined side/chain-main/chain polymer and comblike copolymers with mesogenic and functional acid groups in side chains were studied. The temperature dependences of the effective rotation viscosity (gamma) ₁* were obtained. At close molecular weight and temperature the (gamma) ₁* value for linear polymer exceeds that for comblike combined polymer. Therefore, the existence of side mesogenic groups decreases the velocity of the orientational processes of polymer nematic. However, the highest values of effective rotation viscosity were obtained for the nematic phase of the comblike functionalized copolymers. Hence, the formation of hydrogen bonds in these copolymer leads to slowing of orientational processes. Influence of the intermolecular hydrogen bonds on dynamic properties of functionalized copolymers is stronger than that of intramolecular hydrogen bonds.

Films of Poly-Tetra-Fluoro-Ethylene (PTFE) have been shown to be very effective alignment agents for liquid crystal materials. Such films may be deposited in a one step dry process offering advantages in terms of both time and simplicity over deposition of polyimide or SiO₂ alignment layers. This is most appropriate for applications where a test device is required as part of a rapid prototype for ergonomic and similar testing. Earlier work has identified suitable deposition parameters (temperature, surface pressure, velocity) for production of PTFE films but with single films there is still typically some variation in the alignment due to the machined surface of the PTFE bar itself. In this work multiple film deposition using a 'step and repeat' has been investigated as means of achieving improved alignment uniformity and has been found effective in test devices of several cm². Electro-Optic measurements on a multiple pixel test device show little spatial variation in the threshold voltage illustrating the possibility of matrix addressing a PTFE aligned prototype device. In conclusion PTFE films offer a very rapid method of producing alignment layers for devices having reproducible and uniform electro-optic characteristics.

An application of thermosensitive PDLCs containing chiral nematics in general physics course is described. Several examples of students' exercises and lecture demonstrations concerning heat effects are presented.

Thin polymer layers containing liquid crystal LC of non- linear optical properties were obtained from polyacrylic acid. Samples were produced by phase separation as a consequence of chemical polymerization (PIPS method) resulting in precipitation of liquid crystals in the form of droplets in a polymer matrix being formed. Films were produced in variable conditions of polymerization time and temperature and different content of an initiator (1 - 3 wt%). They contained of 10 - 40 wt% of LC. The cell thickness was constant and equal to 20 micrometers . Systems obtained in this way were subjected to thermo-optical and electro-optical studies, morphological structure investigation and DSC analysis. The polymerization time has a significant influence on the size and number of LC droplets. The presence of benzoyl peroxide can cause partial destruction of LC properties which is reflected by a decrease of isotropization temperature T_I of the liquid crystal. An increase of the initiator amount shortens the time of polymerization (t_i), while process enthalpy ((Delta) H) increases. Hence, the liquid crystal separation time decreases as well. Films prepared by this method present good electro-optical properties. Rise and decay times of orientation are short and equal to 2 - 17 ms (depending on driving voltage applied) and about 80 ms, respectively. Threshold voltage for the best sample is equal to 5 V. Optimal conditions are found: LC content equals 20%, w_t(i) equals 1%, polymerization temperature T_p equals 100 - 110 degree(s)C.

We probe the mesophase transitions and layer structures in thin ordered smectic liquid crystalline elastomer films by means of x-ray diffraction. Ordered elastomer films of submicrometer thickness are produced by crosslinking freely suspended smectic polymer films. After crosslinking - the mesomorphism is similar to that of the precursor polymer. The smectic layer spacing increases with temperature in the SmC* phase while it decays above the SmC*-SmA transition.

Basic thermal characteristics, i.e. heat capacity and conductivity coefficients, for both homogeneous as well as dispersed liquid crystalline materials and their influence on the quality of the obtained thermograms have been discussed. Some useful conclusions concerning conditions for practical applications and handling of the thermosensitive devices (films and paints) have been drawn. There have been carried out several experiments oriented towards determining the optimum matching of the examined objects and forms and parameters of liquid crystalline layers.

A large series of polymer dispersed liquid crystals (PDLC) films doped by dichroic dye (DD) with different morphology was obtained, by the variety of the starting composition. It was shown that the introduction of black mixture or individual DD with positive dichroism slightly influences on the morphology of PDLC films and changes theirs electro- optical (EO) characteristics.

We report the method of the refractive dispersion determination in the anisotropic refractive indices in a planar liquid crystal layers. The experimental data have been obtained from transmission spectra of a plane parallel Fabry-Perot Filter (FPF) filled with the investigated liquid crystal (LC). Physical basis, experimental techniques and math procedures have been described. We assumed the perpendicular light incidence and the absence of absorption and scattering. The dispersion of both refractive indices has been determined over the visible spectrum. During the test measurement similarity of refraction index for 5 CB (K15 MERCK) with literature values has been obtained. Results for no.602 and no.1292 liquid crystalline mixtures made in Institute of Chemistry MUT are given.