Thermal Properties of Liquid-Crystalline Diols and Corresponding Bis-Urethanes with Mesogenic Groups of Various Structures in Side Chains
摘要:
The liquid-crystalline diols with mesogenic groups of different structures were synthetized and their temperature behavior and existence of mesophases were determined. These compounds were also reacted with phenylisocyanate to form bis-urethanes at the ratio of reactive groups [OH]/[NCO] = 1/1. The changes of phase transition temperatures due to the change of H-O-H to H-N-H interactions have been investigated. Generally, the introduction of a phenylurethane group into the molecule suppresses the occurence of mesophases; in the case of simple mesogens the mesophases disappear completely. Stiff substituents bound to mesogen as end groups (such as the phenyl group, alkoxy group, etc.) stabilize the mesophases to such a degree that the negative influence of urethane group is compensated and the LC properties are recovered.
Thermal Properties of Liquid-Crystalline Diols and Corresponding Bis-Urethanes with Mesogenic Groups of Various Structures in Side Chains
摘要:
The liquid-crystalline diols with mesogenic groups of different structures were synthetized and their temperature behavior and existence of mesophases were determined. These compounds were also reacted with phenylisocyanate to form bis-urethanes at the ratio of reactive groups [OH]/[NCO] = 1/1. The changes of phase transition temperatures due to the change of H-O-H to H-N-H interactions have been investigated. Generally, the introduction of a phenylurethane group into the molecule suppresses the occurence of mesophases; in the case of simple mesogens the mesophases disappear completely. Stiff substituents bound to mesogen as end groups (such as the phenyl group, alkoxy group, etc.) stabilize the mesophases to such a degree that the negative influence of urethane group is compensated and the LC properties are recovered.
A macroscopically isotropic side chain liquid crystal polymer is described containing photochromic mesogenic groups and which through irradiation with light is capable of being permanently or substantially permanently converted into an optically anisotropic phase without having been pre-oriented. The polymer is preferably a polyester between on the one hand either an aliphatic, optionally substituted, .alpha.,.omega.-dicarboxylic acid having a total chain length of up to 24 carbon atoms, or an aryl-, in particular phenyl-, carboxylic acid, and on the other hand an optionally substituted 1,3-propanediol containing the mesogenic group, or a group containing the mesogenic group, attached to the carbon in the 2-position. Furthermore, an optical storage device comprising a film of the polymer.
The liquid-crystalline diols with mesogenic groups of different structures were synthetized and their temperature behavior and existence of mesophases were determined. These compounds were also reacted with phenylisocyanate to form bis-urethanes at the ratio of reactive groups [OH]/[NCO] = 1/1. The changes of phase transition temperatures due to the change of H-O-H to H-N-H interactions have been investigated. Generally, the introduction of a phenylurethane group into the molecule suppresses the occurence of mesophases; in the case of simple mesogens the mesophases disappear completely. Stiff substituents bound to mesogen as end groups (such as the phenyl group, alkoxy group, etc.) stabilize the mesophases to such a degree that the negative influence of urethane group is compensated and the LC properties are recovered.