Direct measurement of fluid mechanical properties of micro space: liquid crystal orientation under shear. Soga, Iwao; Dhinojwala, Ali; Granick, Steve. Department of Materials Science and Engineering, University of Illinois, Urbana, IL, USA. Jpn. J. Appl. Phys., Part 1 (1999), 38(10), 6118-6122. CODEN: JAPNDE ISSN: 0021-4922. Journal written in English. CAN 132:57396 AN 1999:701788 CAPLUS

The shear-induced mol. orientation of a nematic liq. crystal, 5CB (4-pentyl-4'-cyanobiphenyl) was studied in a newly-developed app. in which the liq. crystal was confined between optical windows at a film thickness that is continuously variable. The mol. orientation was measured in situ during shear in the presence and absence of DC elec. bias between the two surfaces. In this preliminary study we present findings for a spacing of 10 mm, which is comparable to the spacing of actual liq. crystal display technol. Fourier transform IR time resolved spectroscopy (FTIR-TRS) synchronized with the shear motion provided the mol. orientation as a function of time during the shear cycle. Only a slight orientation along the shear direction was found in the isotropic state but, in the homeotropic state, the mol. orientations in response to shear reflected a competition process between orientation in orthogonal directions. Shear promoted orientation parallel to the confining plates, and a DC bias voltage promoted orientation perpendicular to the confining plates.