Liquid crystalline alignment

The liquid crystalline characteristics of cinnamate esters have been examined and novel azo bearing systems have been made based on 4-[N-ethyl-N-(2-methacryloyloxyethyl)]amino-4 -(2-cinnamoyloxyethylcarbonyl)-2 -(nitroazoben-zene). Poly[4-(2-methacryloylethoxy)azobenzene] has been found to be valuable for the photocontrol of liquid crystalline alignment as have polymers with benzylidene phthalimidine side chains. Poly(methyl methacrylates) with o-cinnamate side chains undergo polarisation isomerisation resulting in photoalign-... 

T.S. Perova, J.K. Vij, The influence of surface stnicture on the discotic liquid crystalline alignment an in ared spectroscopy study. Adv. Mater. 7, 919-922 (1995)... 

The incorporation of rigid-rod polymers into block copolymers results in extremely rich self-assembly behaviors that differ markedly horn that of traditional block copolymers due to the interplay between microphase separation of the rod and coil components and liquid crystalline alignment. The combination of these effects results in novel stmctures in both solution and melts. 

How is photo-isomerization utilized in liquid crystalline alignment ... 

Another approach to liquid crystalline alignment is based on photoisomerization of azo compounds in polymeric materials or as part of the polymer strueture. In recent years, investigation of the use of azobenzene-containing... 

Perova, T. S. Vij, J. K. The influence of surface structure on the discotic liquid crystalline alignment an infrared spectroscopy study. A fl. Mater. 1995, 7,919-922. 

Especially in the early stages of TFT device production, the destruction of thin film transistors by static electricity was a serious problem because the reliability of the transistors was quite low. This problem has been dealt with gradually. However, the occurrence of fibre dust has been a continuing problem, and has imposed restrictions on production lines. Moreover, the mechanism of the liquid crystalline alignment is not clearly understood. 

It is well known that the main reason for liquid crystalline alignment on rubbed polymer surfaces is the anisotropic characteristics of the stretched polymer surfaces, although it is also due to microgroove structures [1]. 

In all cases, it has been reported that microgrooves with a pitch smaller than 1 pm can realize liquid crystalline alignment giving a practical contrast. Figure... 

Fig. 3.4.3 Liquid crystalline alignment on alignment layer surfaces, (a) Two possible directions of molecular inclination on an alignment layer surface and a tilt reverse disclination. (b) The direction of molecular inclination on a rubbed...

Structure of polyimide LB Blms and liquid crystalline alignment on the film... 

Liquid Crystalline Alignment on Chemically Treated Surfaces... 

Polynuclear complex salts of chromium, aluminum, iron and cobalt are reported to have been used to form the alignment layers for liquid crystalline materials [2-3]. In Fig. 3.7.2 are the structures of layers on glass surfaces treated by carboxylatochromium complexes of (a) an alkanoic acid and (b) an alkandioic acid. Glass surfaces treated by n-alkanoic acids with more than 3 carbon atoms induce homeotropic liquid crystalline alignment as indicated in Fig. 3.7.2(a). On the other hand. Fig. 3.7.2(b) shows the structure of glass surfaces treated by carboxylatochromium complexes of an alkandioic acid. These surfaces show homogeneous... 

Figure 4.5.7 [6] shows the transmittance dependence on the interval between the protrusion, s. The larger the interval (s), the higher the transmittance becomes. However, for intervals larger than 30 pm, no dependence can be observed. This suggests that the protrusions do not influence the liquid crystalline alignment in areas far from them. 

Other aspects are that linear polymers without crosslinking possess thermoplastic properties, which means they can be plastically deformed on heating and can retain the deformed situation on cooling. In the rubbing process, the plastic polymer is sheared and retains the extended state. These processes change the chain orientation and can cause partial crystallization, which can induce epitaxial growth of smectic liquid crystalline alignment. 

In Table 5.2.2, thermoplastic polymers with substantial side groups on which good alignment could not be observed, are shown. The deterioration of smectic liquid crystalline alignment due to the lack of linearity of the polymers with substantial side groups can be confirmed. 

This book discusses liquid crystalline alignment technologies investigated, mainly in industrial laboratories, from the early 80s to 2000. The authors are researchers who have been studying liquid crystalline aligimient or developing LCDs during that period at the laboratories of their respective companies (Sharp, Toshiba, Japan IBM). 

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