Site: Institute of Physics
Ukraine Academy of Sciences
pr. Nauki, 46
252650 Kyyiv, Ukraine
Telephone: 7 (044) 265 0909
Fax: 7 (044) 265 1589
E-mail:
sbpol%lls.Kiev.ua@relay.ussr.eu.net

Date Visited: October 26, 1993

Report Author: O.D. Lavrentovich

ATTENDEES

WTEC:

M.J. DeHaemer
O.D. Lavrentovich

HOSTS:

Mykhailo Semenovych Brodin

Academician, Director of the Institute
Telephone: 7 (044) 265 1220

Mykhailo Vasylyovych Kurik,

Professor, Doctor of Science

Gertruda Vasylivna Klimusheva

Professor, Doctor of Science

Oleg Georgiyovych Sarbei

Professor, Doctor of Science

Anatolii Ivanovych Khyzhnyak

Professor, Doctor of Science

Yurii Oleksandrovych Reznikov , Ph.D.

BACKGROUND

The Institute of Physics (IP) of the Academy of Sciences of Ukraine, founded in 1929, is one of the oldest physics research institutions in Ukraine. It comprises twenty-six scientific departments and laboratories. The staff consists of more than 600 persons.

Traditionally the IP performs fundamental and application- oriented research. Presently the main directions are as follows:

The IP organizes regular International Schools-Conferences on Liquid Crystals (ISCLC). The last V ISCLC, "Nonlinear Optics Of Liquid Crystals, Photorefractive and Heterogeneous Media," was held in Sevastopol, Crimea, October 19-24, 1993. The ISCLCs are attended by representatives from Belarus, France, Italy, Russia, and Ukraine.

RESEARCH AND DEVELOPMENT ACTIVITIES

The Institute of Physics started a pioneer investigation in the physics of liquid crystals in 1970 (Professor M.V. Kurik). The IP holds a leading position in Ukraine in liquid crystals research and development. An important advantage of the IP is that the R&D was initiated in different departments as a field of activity in addition to basic scientific interests (solid state physics, nonlinear optics, NMR, etc.). This allowed the use of different advanced experimental approaches. The WTEC team visited four laboratories.

Department of Molecular Photoelectronics

(Head: Prof. M.V. Kurik. PIs: Prof. Vasyl V. Sergan, Prof. Olexandr V. Kovalchuk, and Prof. Vasyl G. Nazarenko)

The R&D interests in molecular photoelectronics include PDLCs, cholesteric-based front-lit display cells (in collaboration with the Monocrystal Institute, Kharkiv, and Institute of Semiconductors, Kyyiv), and surface phenomena in liquid crystals (in collaboration with the LCI, Kent State and Laboratoire de Physique des Solides, Universit' Paris-Sud, France). The main types of structural transformations in dispersed nematic drops were studied for PDLC both theoretically and experimentally (Bodnar 1992). The existence of polar electro-optic effect induced by a surface polarization of a nematic liquid crystal was discovered and investigated (Lavrentovich 1991, 1992).

Laboratory of Optics of Multibeam Processes

(Head: Prof. Anatolii I. Knyzhnyak)

To achieve a homogeneous alignment, one usually uses buffed polymer layers. The mechanical treatment of the substrate is thus an important part of the display technologies. However, the homogeneous treatment can be achieved also by photopolymerization of the substrate. The collaboration of the IP (Prof. Yu. A. Reznikov) with An-Yang Research Laboratory, Goldstar R&D Complex (Korea), Hoffmann-LaRoche (Switzerland), and Niopik (Russia) has resulted in patent applications (Chigrinov; Park 1993[a]; Park 1993[b]) on a new method of nonmechanical liquid crystal alignment and a new method of LC oblique orientation product for this photosensitive polymeric orientants. Oriented polymer coating is prepared by photochemical polymerization of poly(vinyl cinnamate) or its fluorinated analog using linear polarized light. The easy direction of the liquid crystal orientation appears due to the orientationally-ordered chemical cross-links between the polymer chains.

The exposure time is ~10 min. The corresponding polar and azimuthal anchoring coefficients are 5 * 106 J/m2 and (0-10) * 106 J/m2, respectively. The most recent improvement achieved by Prof. Reznikov's group is the controllable tuning of the pretilt angle within the range 0-15 degrees. The orientation is stable during at least three years; the temperature limit of the stability is 60 degrees centigrade.

The Laboratory also performs R&D in the area of "filled nematics," that is, nematic liquid crystal filled with small silica particles.

Department of Physics of Crystals

(Head: Professor G.V. Klimusheva)

Research and development interests in the physics of crystals include the following:

Department of Solid State Electronics

(Head: Prof. Oleg G. Sarbey)

The research group has developed the characterization facilities to measure the basic parameters of nematic liquid crystals: refractive indices, dielectric susceptibilities, elastic constants, K11, K22 and K33, pretilt angle, and the polar anchoring coefficient in the temperature range from -10 to 90 degrees centigrade (except the Abbe-refractometer measurements of the refractive indices, where the range is limited by 15 degrees centigrade from below).

During the visit, the WTEC team attended a special seminar where the representatives from different Ukrainian institutions presented the results of R&D in liquid crystals.

Institute of Organic Chemistry, Ukraine Academy of Sciences (Kyyiv)

(Represented by Prof. Yurii Arkadiyovych Fialkov)

The institute performs synthesis of the fluorinated liquid crystalline compounds; the chemical and thermal stability of the fluorinated compounds is typically higher than that of the conventional compounds. First, the mesogenic fluorinated derivatives of MBBA are synthesized. The attempts to synthesize the fluorinated derivatives of the cyanocompounds (which are important for applications because of large dielectric anisotropy) led to nonmesomorphic compounds or compounds that show only the smectic phase. However, the fluorinated compounds that contain CN groups and exhibit the nematic phase were finally obtained (Moklyachuk 1990), as shown in Figure Physics.1.


Figure Physics.1. Crystal (76 degrees centigrade) nematic (101 degrees centigrade) isotropic phase.

This compound belongs to a new type of mesomorphic compounds, arilperfluoropolienes, which produce highly thermostable smectic and nematic phases.

Monocrystal Institute, Ukraine Academy of Sciences

Address: 310001 Kharkiv, Lenin av., 60

(Represented by Prof. Olexander A. Gerasimov, Prof. Valerii V. Vaschenko, and Prof. Vitalii G. Tischenko)

R&D is concentrated on synthesis of cholesteric (cholesterol derivatives) and chiral nematics. The cholesterol derivatives are synthesized from biological materials (cattle marrow) and are used in production of different thermoindicators and thermochromic films (Prof. V.G. Tischenko).

The institute has developed chiral-nematic mixtures that can be used in the front-lit displays (Prof. O.A. Gerasimov). An external electric field switches the cholesteric structure between three basic states: homogeneous (planar), untwisted nematic, and focal conic domain textures. The display does not require polarizers. The underlying physical mechanism of the display is close to that proposed earlier by J.W. Doane and D.K. Yang of the Liquid Crystal Institute, Kent State University. The display technology is being developed in collaboration with the Institute of Semiconductors (see below) and the Institute of Physics, Kyyiv.

According to Prof. L.A. Kutulya, the institute offers the following:

SUMMARY

The Institute of Physics is a leading Ukrainian institution in the field of the physics of liquid crystals, and has an excellent team of researchers needed to remain one of the strongest liquid- crystal research centers in the world. Some developed techniques (e.g., nonrubbing alignment method) and materials (e.g., PDLC films) can be used in the displays industry. Collaboration with other institutions (e.g., Korolyov, Kyyiv, Monocrystal, Kharkiv, and Zhovten, Vinnutsya) can lead to successful manufacturing of LC-based devices in Ukraine.

REFERENCES

Bodnar, V. G., O.D. Lavrentovich, and V.M. Pergamenshchik. 1992. "Threshold of Structural Hedgehog-Ring Transition in Hematic Droplets in an Electric Field." Sov. Phys. JETP:74.

Chigrinov, V.G., V.M. Kozenkov, N.V. Novoseletskii, V. Yu. Reshetnyak, Yu. A. Reznikov, M. Schadt, and K. Schmitt. "Preparation of oriented photopolymers using polarized light." Eur. pat. appl. EP 525:477.

Lavrentovich, O.D., V.G. Nazarenko, V.M. Pergamenshchik, V.V. Sergan, and V.V. Sorokin. 1991. "Surface Polarization Electrooptic Effect in a Nematic Liquid Crystal." Sov. Phys. JETP 72:431.

Lavrentovich, O.D., V.G. Nazarenko, V.V. Sergan, and G. Durand. 1992. "Dialectric Quenching of the Polar Instability in a Nematic Liquid Crystal." Phys. Rev. A15 45:6969.

Moklyachuk, L.I., M. Yu. Kornilov, Yu. A. Fialkov, M.M. Kremlyov, and L.M. Yagupolsky. 1990. J. Org. Khim. 26:1533.

Park, W.S., H.H. Shin, S.B. Kwon, T. Ya. Marusii, Yu. A. Reznikov, A.I. Khyzhnyak, and O.V. Yaroshchuk. 1993a. "A method of liquid crystal oblique orientation production on photosensitive polymeric material." Korean patent appl. No. 93-8698.

Park, W.S., H.H. Shin, S.B. Kwon, A.G. Dyadyusha, T. Ya. Marusii, Yu. A. Reznikov, A.I. Khyzhnyak, O.V. Yaroshchuk, A.A. Kolomeytsev, and I.V. Gerus. 1993b. "Thermostable photopolymeric material for liquid crystal alignment." Korean patent appl. No. 93-8698.

Polishchuk, A., and T.V. Timofeeva. 1993. "Liquid Crystalline Metal-Containing Phases." Uspekhi Khimii. 62:319.


Published: December 1994; WTEC Hyper-Librarian