Thermotropic liquid crystal polymers applications

Chung TS, editor. Thermotropic liquid crystal polymers thin-film polymerization, characterization, blends, and applications. Lancaster, PA TechnomicPub. Co. 2001. ISBN 1566769434. 

Thermotropic Liquid Crystal Polymers Thiil-film Polymerizadon, Characterization. Blends, and Applications... 

A. A. Collyer, Thermotropic liquid crystal polymers for engineering applications. Materials Science and Technology, 5, 309 (1989). 

The industrial development of thermotropic liquid crystal polymer (LCP) materials can be traced from its theoretical origins, through the identification of useful compositions, to full commercialization. The future industrial challenge will be to define and develop applications which take advantage of the unique properties of these materials. 

Roggero, A.D., Applications of Thermotropic Liquid Crystal Polymers and Thermotropic Liquid Crystal Polymer Blends in Thermotropic Liquid Crystal Polymer Blends, F.P. La Mantia, ed., Technomic, (Lancaster, PA) (1993) pp 157-175. 

On the other hand, the interest towards this field is accounted for by the possibility to create polymeric systems, combining the unique properties of low-molecular liquid crystals and high molecular compounds, making it feasible to produce films, fibers and coatings with extraordinary features. It is well-known that the utilization of low-molecular thermotropic liquid crystals requirs special hermetic protective shells (electrooptical cells, microcapsules etc.), which maintain their shape and protect LC compounds from external influences. In the case of thermotropic LC polymers there is no need for such sandwich-like constructions, because the properties of low-molecular liquid crystals and of polymeric body are combined in a single individual material. This reveals essentially new perspectives for their application. 

More recently,thin walled articles have been fabricated by blow-molding composites of liquid crystal polymer (LCP) and expanded porous polydetrafluoroethylene sheetingl l material. Container application examples include food and pharmaceuticals, automotive gas tanks, bottles, and other vessels. Unlike most other thermoplastic polymers, thermotropic LCP forms high-viscosity melts that have thixotropic characteristics. Applying shear force to the melt substantially alters the melt viscosity of LCP and the orientation of its polymer domains. These attributes are useful to... 

There has been considerable interest in recent years in the study of liquid crystalline order in polymeric materials. Following on from the use of small molecules in display applications, the possibility of creating polymers with similar characteristics became attractive. Onsager and Flory predicted that rigid rod-like macromolecules should form liquid crystalline phase. However, it was not until 1975 that the first observation of a thermotropic liquid crystalline polymer was reported. Several reviews have been published on polymeric liquid crystals. ... 

We are all familiar with gases, liquids and crystals. However, in the nineteenth century a new state of matter was discovered called the liquid crystal state. It can be considered as the fourth state of matter (although plasmas are also candidates for this accolade). The essential features and properties of liquid crystal phases and their relation to molecular structure are discussed in this chapter. Specifically, the focus is on thermotropic liquid crystals (defined in the next section). These are exploited in liquid crystal displays (LCDs) in digital watches and other electronic equipment. Such applications are outlined later in this chapter. Surfactants and lipids form various types of liquid crystal phase but this was discussed separately in Chapter 4. Finally, this chapter focuses on low molecular weight liquid crystals, liquid crystalline polymers being touched upon in Section 2.10. 

It is very often the commercial interest in novel materials which stimulates the growth in their study and eventual exploitation. This is certainly true in the case of thermotropic liquid crystals and their application in electro-optic displays. Indeed, the production of high-strength, high-modulus fibres has seen a wealth of interest in lyotropic main chain polymers. The use of lyotropic side chain polymers has, by comparison, been less well publicized. This is not to say that there are no applications. Alkyl polyoxyethylene surfactants attached to polysiloxane polymers have found uses in many personal care products such as liquid soaps, shampoos, skin creams, and hair mousses. Unfortunately the physical properties of these and other similar materials have been closely guarded secrets and the amount of information available in the literature is low. The limited data which does exist, however, provides us with some interesting structure - behaviour relationships. 

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