Site: Moscow State University
Date Visited: October 29, 1993
Report Author: M. Slusarczuk
Professor Valeriy V. Lunin
Professor Valery P. Shibaev
Professor Andrej Aleksandrov
The WTEC team was introduced to the capabilities of the Chemistry Department by the dean, Professor Lunin. The department has a broad range of capabilities. It consists of seventeen divisions that cover such diverse research areas as medical and pharmaceutical materials, ecological problems, and high- temperature superconductors.
Professor Valery Shibaev's area of interest is the synthesis, study, and application of liquid crystal materials. In particular he has focused on high molecular mass polymer liquid crystals, mesogenic groups that are connected to a main chain with methylenic and oxymethylenic fragments as spacers. Main chains are acrylic, polyesters, polysiloxanes, and polyether- type. These materials are obtained by copolymerization of chiral mesogenic monomers with nematogenic monomers. The macromolecular nature of cholesteric polymers predetermines the creation of the frozen cholesteric structure in solids, films, and coating.
The Shibaev group has fabricated a polarizing filter material using the cholesteric phase with selective reflection based on the percentage of the chiral component. The resultant filters can span the visible through IR spectra and are good, for example, for laser light protection. They operate both in the reflective and transmissive mode. This feature opens up the wide perspective for obtaining spectrum filters and reflectors, circular dichroic optical filters, and color-controlled optical elements, regulated by electrical field.
All cholesteric polymers have good adhesion to glass, paper, and polymer supports. This adhesion permits the depositing of cholesteric polymers as the thin films (10-100 nm) on these materials. Different polarizing optical devices can be produced on the base of cholesteric polymers in combination with retarded foils (optical diodes, switchable light filters, etc.). With menthol derivative additives, the cholesteric polymers can produce both right- and left-hand materials.
The Shibaev group has good characterization and analysis capability, including NMR, X-ray diffraction, gel permeation chromatography, SEM, TEM, UV-visible-IR spectrometry, and polymer orientation with electrical and magnetic field. The present university budget covers only salaries and does not provide for improvement or maintenance of equipment.
An interesting project being carried out by Professor Shibaev is an information storage device based on amorphous and highly- oriented liquid crystalline polymeric materials that contain dye molecules chemically linked to the main chain. These dye molecules can be transformed from the trans to the cis form under laser illumination. This in turn changes the ratio between refractive indices in the X and Y directions. The process is reversible and the recorded information can be erased with a laser beam with changed plane polarization. He showed team members a photograph created in this manner. The recording time is relatively long -- ten seconds for the photograph. The storage density is very high -- 109 bits/cm2. He has had information stored at least two years without degradation. Practically speaking, the phenomena found by the Shibaev group offers new possibilities for orientation of polymers and for optical data storage with respect to storage density and reversibility. The induced optical anisotropy can be modified continuously and reversibly by rotating the plane of polarization of the laser beam in relation to the film. Any type of orientation on the molecular level can be created by using these films under the laser illumination.
The Physics Department performs research on thin films, in particular, ordered deposition of organic films. The source material is heated in a vacuum (10-1 to 10-8 Torr), creating a molecular beam of organic material that condenses on the substrate. The resultant film is very uniform and very thin (about 1,000 ), and can be oriented normal or parallel to the surface. It can be used to replace the alignment layer in a liquid crystal cell. They are also experts at depositing linear carbon films, especially for medical components to be implanted in the body.