Electro‐optical characteristics in phase separated liquid crystal/photo‐curable acrylic monomer mixture system

One of the main objectives of the experiment was to achieve the vertical aligned (VA) effect. To accomplish this, we employed liquid crystal (LC)/photo‐curable acrylic monomers mixture systems to prepare vertical alignment copolymer film (VACOF) for LC molecules with the photo‐polymerization induce phase separation (PIPS) process. From previous experimental results, we successfully fabricated LC devices without the micro‐protrusion structure. After the application of a saturated voltage, the LC molecules actually exhibited such interesting phenomena as uniaxial orientation, uniform single‐domain display state, etc. In this study, to obtain VACOF with smooth surface, we similarly controlled appropriate experimental conditions such as UV light exposure intensity and curing temperature, and altered process parameters such as the cell thickness, chemical structure length of the main chain type biphenol acrylic monomer to simulate the main chain function of the traditional vertical alignment type polyimide (PI)], etc. During the experiment, we discovered that regardless of the cell thickness, this photo‐alignment system would yield the VACOF instead of the polymer disperse liquid crystal (PDLC) film morphology. Another notable finding was that the contrast ratio was heavily influenced by the length of the main chain type acrylic monomer structure for LC/monomer mixture systems, with enhancement of up to ～56%. Therefore, we further investigated the display effects, electro‐optical properties, etc. for these two main chain type acrylic monomer systems with different lengths and cell thicknesses. Copyright © 2011 John Wiley & Sons, Ltd.