Liquid-crystal-like superstructure

Finally, an area that will most likely see an explosive growth over the next few years is the self-assembly of nanoparticles covered with mesogenic and pro-mesogenic capping agents. A number of different approaches have been summarized in this review, and the formation of nematic, smectic-like, cubic, and columnar phases and/or superstructures have been demonstrated. Once more, the possibilities to produce such metamaterials using nanoparticles and liquid crystal motifs are endless, and future research will surely discover other, in part, more complex phase morphologies as well as uniquely tunable nanoscale properties as a result of liquid crystal phase formation. 

We will consider below self-assembled superstructures, like collagen, plant cell walls, starch and the contractile macromolecular complex. These super structures are also liquid crystals, evident from their birefringence and rheological properties. With increasing knowledge of the molecular mechanisms behind function, however, there has been an unfortunate tendency to neglect the role of overall structure. 

Liquid crystals are organic compounds in a state of matter intermediate between that of an isotropic liquid and an anisotropic crystalline soUd. Most liquid crystalline molecules are markedly elongated and rod like. In nematic liquid crystalline materials, the directions of the long molecular axes (directors) are arranged parallel to each other. Adding a chiral molecule to a nematic phase causes a superstructure comparable to the steps of a spiral staircase. The structure can be understood as... 

In Section 9.2.1 of this Chapter we discussed field-induced changes in the microstructure of liquid crystals. However, field-induced unwinding of the cholesteric (macroscopic) helix (see Section 9.3.2.3 of this Chapter) shows that the transition from a twisted to a uniform nematic may also be considered as a phase transition. In the latter case the field energy term competes with a rather small elastic energy proportional to nematic-like elastic moduli and the squared wave vector of the helical superstructure Kq As the pitch of the helix p = lKlq is large, the field threshold for the transition is very low. On the other hand, between the two extreme cases (a microstructure with a molecular characteristic dimension and a... 

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