Optical and structural properties of new discotic acrylates polymerized in the discotic nematic phase

Abstract

Discotic liquid crystals can be used as optical compensation layers to improve the viewing angle of twisted nematic liquid crystal displays, for example. The in situ photopolymerization of newly synthesized acrylates is shown to result in oriented films with a negative birefringence. The transition temperatures, birefringence, and thermal stability were measured and the structure of the polymers was determined by wide‐angle X‐ray diffraction in order to explain the difference in optical properteis between various polymers.

Discotic liquid crystalline crosslinkers and anisotropic networks

“…Because of the frozen nature of mer [8]. In the present case, a pretransitional arrangement cannot justify the relatively high birefringence of poly (1), the extrapolation method of Haller cannot be applied.…”

“…organic layer was dried over MgSO 4 and evaporated. The intermediate product 8 and pyridinium p-tolueneThe organic layer was dried over anhydrous magnesium sulphate and the solvent was evaporated. The resulting sulphonate (3.11 g, 0.012 mol) were dissolved in 80 ml of ethanol and heated to 60ß C (to remove the THP solid product was shaken 3 times with 20 ml of ethanol to remove the unreacted side group materials.…”

“…We synthesized triphenylene hexabenzoate derivatives with acrylate end groups, aligned them in the discotic nematic (N D ) phase and polymerized them [7] (® gure 1). The resulting ® lms exhibit a thermally stable negative birefringence [7,8] and can be used as compensation foils to enlarge the Figure 1. Schematic representation of the crosslinking polyviewing angle of twisted-nematic liquid crystal displays merization in the N D phase of a discotic liquid crystal with six reactive end groups.…”

A columnar mesophase with high lateral order from a triphenylene-hexa(3,5-dialkoxy)benzoate

“…It has also been observed that small methyl substituents at the para position on the benzoate moieties depress mesophase transition temperatures, broaden liquid crystal windows and influence phase sequences of these compounds [13,14]. Based on acrylated benzoate esters of 2,3,6,7,10,11-hexahydroxytriphenylene, stable anisotropic films have been obtained by photopolymerisation [15,16]. It is also known that introduction of large bulky substituents causes thickening of the molecules and weakens the face-to-face interactions.…”

Polymeric Optical Films as Patterned Retarders and Alignment Layers for Transflective Liquid Crystal Displays

“…Particularly, polymerizable liquid crystalline (PLC) materials have been widely used for producing brightness enhancement films [1], reflective polarizers [2,3], compensation films [4][5][6], and retarders [7][8][9] in liquid crystal 25 displays (LCDs). In these cases, the PLC should be processed into an optically anisotropic film structure where an alignment layer is typically needed for orienting the PLC molecules.…”