ELECTROOPTICAL PROPERTIES OF POLY(DIISOPROPYL FUMARATE-CO-STYRENE) CYANOBIPHENYL-TYPE LIQUID-CRYSTAL COMPOSITE FILMS

Composite films composed of poly(diisopropyl fumarate-co-styrene) (PFS ) and nematic-type liquid crystal (E8) (40/60 by weight) were prepared by solvent casting in chloroform at room temperature. Scanning electr on microscopy measurement showed that a liquid crystal phase is contin uously embedded in a spongy-like PFS martrix. Optical responses of the composite films under the conditions of an externally imposed ac elec tric field (60-240 V-p-p, 10-1000 Hz),temperature (290-355 K), and a f ilm thickness (8-16 mu m), were determined using an He-Ne laser (wavel ength 632.8 nm). The results obtained indicated that, under the condit ions imposed, the output can be continuously controlled, and the respo nse time is only of several milliseconds or less. In addition, the res ponse to temperature sweep, heating and cooling, was reversible with o nly a delay, and it was interpreted in terms of the rigidity and therm al stability of the matrix polymer. (C) 1993 John Wiley and Sons, Inc.