Polymer Network-Stabilized Liquid Crystals

Abstract

The fabrication and properties of polymer network±stabilized liquid crystals, formed by polymerization of a small amount of a bifunctional photoreactive monomer dissolved in a liquid-crystalline phase, are reviewed. The polymer network morphology is strongly related to preparation conditions such as monomer content, polymerization temperature, and ultraviolet (UV) curing conditions. The transfer of anisotropic liquid-crystalline order onto the network is discussed in detail. The electro-optical performance of network-stabilized nematics, cholesterics, and ferroelectric smectics is largely dependent on the morphology of the network, as will be demonstrated with an emphasis laid on polymer-stabilized cholesteric textures (PSCTs). A general correlation between polymerization conditions, network morphology, and electro-optical behavior will be outlined and aspects concerning applications discussed.

Hydrogels with self-assembling ordered structures and their functions

“…Inspired by nature, molecular self-assembly that is directed through weak, noncovalent interactions has received tremendous attention for the development of systems with ordered structures and resultant functions [1,2,6,7]. Th ese eff orts have resulted in various functional materials based on self-assembled structures including solutions, elastomers, gels and hard materials [1,2,[7][8][9].Gels as a functional system is an emerging fi eld in themselves, possessing a responsiveness to external stimuli such as stress, light, temperature, pH and ionic strength [10]. Gels with molecular assemblies can be produced in organic solvent (organogels) or aqueous solvent (hydrogels).…”

Functional liquid-crystalline polymers and supramolecular liquid crystals

“…[232][233][234][235][236] LC GELS Two types of LC gels have been reported: LC chemical gels and LC physical gels (Figure 14a). While LC chemical gels are composed of conventional liquid crystals (liquid crystal solvent) and cross-linked LC polymers, 239,240 for LC physical gels, liquid crystals are mixed with low-molecular weight gelators that form self-assembled fibrous networks. 241,242 The resulting materials exhibit elastic mechanical Functional liquid-crystalline polymers T Kato et al properties compared to conventional liquid crystals, but preserve the dynamics and stimuli-responsive properties of small molecules of liquid crystals.…”

“…In the LC chemical gels, the gelation is achieved by the in situ crosslinking of polymerizable mesogens dissolved in a LC solvent. 239,240 The presence of mesogenic groups attached to polymer networks provides the proper miscibility with the mesogens trapped by a 3D polymer network. Owing to their dynamic properties, LC chemical gels have been widely investigated for their application to optical devices.…”

Ferroelektrische Flüssigkristalle: Binär schaltbare Flüssigkristalle eignen sich für schnellere Displays

“…Insbesondere der kürzlich gelungene Nachweis einer spontanen Polarisation in Phasen achiraler Moleküle, den so genannten "Bananenmolekülen", hat ein weites Feld für zukünftige Forschung eröffnet. Anwendungstechnisch könnten neben den oben aufgeführten Technologien auch der DHF-Effekt (deformed helix ferroelectrics) sowie polymer-disperse und -stabilisierte FLC [9] interessant werden. Dabei bleibt zu hoffen, dass die zukünftige industrielle Entwicklung neuer Produkte, basierend auf (ferroelektrischen) Flüssig-kristallen, nicht ausschließlich in asiatischen Ländern stattfindet, sondern auch dort, wo ein nicht geringer Teil der Grundlagenforschung an diesen Systemen geleistet wird.…”