Effects of surfactant and molecular weight of polyol on grating formation and switching of holographic PDLC

Abstract

The interposition of surfactants between polymer and liquid crystal (LC) droplets was theoretically predicted by the positive spreading coefficient (0 < l 31 ) and utilized to interpret the morphology, grating formation kinetics, diffraction efficiency, and switching of the holographic polymer dispersed liquid crystal (HPDLC), prepared from various types (octanoic acid, poly oxyethylene octyl phenyl ether, and perfluoro-1-butanesulfonyl fluoride) and amounts (0--9 wt%) of surfactant and molecular weights of polyol (PPG). Regardless of the surfactant type, diffraction efficiency increased with the addition and increasing amount of surfactant, a tendency consistent with increasing value of spreading coefficient, which is determined by the formulations of grating formation. In contrast, diffraction efficiency showed a maximum with the polypropylene glycol (PPG) molecular weight. Surfactant effectively reduced the anchoring energy and electrically drove the film which otherwise was not driven. Overall, surfactant with greater l 31 gave smaller droplet, greater diffraction efficiency, driving voltage, contrast ratio, and smaller response time.

The color properties of a reflective CMYK module using polymer‐dispersed liquid crystal (PDLC)

“…Polymer‐dispersed liquid crystal (PDLC) films are composed of micro‐droplets of liquid crystal (LC) embedded within polymer matrix . A thin PDLC film sandwiched between two transparent electrodes transmits light when an applied electric field orients the LC molecules parallel to the field .…”

“…Polymer-dispersed liquid crystal (PDLC) films are composed of micro-droplets of liquid crystal (LC) embedded within polymer matrix. 1,2 A thin PDLC film sandwiched between two transparent electrodes transmits light when an applied electric field orients the LC molecules parallel to the field. [3][4][5] PDLC films could be easily prepared by the methods of photo-induced phase separation (PIPS), solventinduced phase separation, temperature-induced phase separation, and reaction-induced phase separation.…”