Smectic liquid crystal network

Hirschmann et al. (1991) synthesized a smectic liquid crystal network whose side chains contain NLO active groups. After the poling with the... 

F. 2.17 a Schematic representation of the formation of the nanoporous membrane based on smectic liquid crystals, b The chemical structure of the LCs. c Simplified artistic view of the nanopores in the layered network. To visualize the 2D pores the counter ion is not shown and the benzoic acid derivatives are drawn highly ordered, d A free-standing H-bonded polymer network, e TEM of the nanoporous polymer network filled with barium ions, scale bar 20 nm. f X-ray diffraction pattern of the alkaline treated network. Adapted from Ref. [76] by permission of John Wiley Sons Ltd... 

Aldred, M.R, et al. Organic electroluminescence using polymer networks firom smectic liquid crystals. Liq. Cryst. 33(4), 459-467 (2006)... 

Nematic gels are very interesting systems, thus deserving further study. Actually, these systems are being studied experimentally for applications. Examples are polymer dispersed liquid crystal displays are sometimes dispersed not in a polymer, but in a polymer network. Displays by means of the polymer stabilized cholesteric texture change, are also achieved in crosslinked systems. In addition, the chiral smectic phase has been obtained in such systems as well. Other types of liquid crystal gels have been applied or are expected to be applied in such devices. 

The liquid crystalline polymer has since developed far beyond imagination that a decade ago. The liquid crystalline polymer family has so far included the main chain-, side chain-, and crosslinked- (i.e. network or elastomer) types, and their solutions and gels. The liquid crystal phases cover nematic, cholesteric and smectics. Although the science of the liquid crystalline polymer is not fully mature, it has attracted significant research interests and has already made tremendous progress. As investments and human resources continue, the liquid crystalline polymer is expected to have an even brighter future. 

Mesophases can be locked into a polymer network by making use of polymerizable LCs [59]. These molecules contain moieties such as acryloyl, diacety-lenic, and diene. Self-organization and in situ photopolymerization under UV irradiation will provide ordered nanostmctured polymers maintaining the stable LC order over a wide temperature range. A number of thermotropic liquid crystalline phases, including the nematic and smectic mesophases, have been successfully applied to synthesize polymer networks. Polymerization of reactive lyotropic liquid crystals also have been employed for preparation of nanoporous polymeric materials [58, 60]. For the constmction of nanoporous membranes, lyotropics hexagonal or columnar, lamellar or smectic, and bicontinuous cubic phases have been used, polymerized, and utilized demonstrated in a variety of applications (Fig. 2.11). 

Keywords Chain conformation Cholesteric Elastomer Liquid crystal Liquid crystal polymer Nematic Polymer networks Smectic... 

Lu Yang, Wei Jie, Shi Yang, et al. Effects of fabrication condition on the network morphology and electro-optical characteristics of polymer-dispersed bistable smectic A liquid crystal device. Liq. Cryst. 40 no. 5 (2013) 581-588. 

---