Polymeric ionic liquid crystals polymerization

Abstract Ionic liquid crystals (ILCs) are emerging as interesting materials since they are expected to combine together the technological properties of ionic liquids (ILs) and liquid crystals (LCs). In this chapter, we will present a survey of the literature of the last 5 years, from 2005 to mid-2010 concerning ILCs. The chapter is divided into four sections ILCs based on organic cations (and anions), metal-based ILCs and polymeric ILCs, and applications of ILCs. 

Thermotropic side-chain ionic liquid-crystalline polymers are particularly attractive when the aim is that of merging the liquid-crystalline characteristics of the low molecular weight mesogen side groups with the mechanical properties of the polymeric main chain. It is not surprising, then, that they attracted most of the research efforts in the polymeric ionic liquid crystals field. 

Chapter 4 examines the development of ionic liquid crystals (ILCs) based on organic cations (and anions), metal-based ILCs and polymeric ILCs, and their important applications. 

A coordination number of 6 is common for a metal ion. Small, highly charged cations, such as Be + and Al +, have low coordination numbers, although these coordination numbers are usually higher in crystals than in gases or liquids. For example, beryllium chloride, BeCU, in the gas phase, exists as an isolated linear molecule," with coordination number 2 (not truly ionic) in crystals, however, it exists as a polymeric, bridged structure in which the beryllium has the preferable coordination number of 4 (Figure 15.5). Ionic radii vary somewhat with coordination number, and are shorter if the coordination number is smaller. For example, a cation with a tetrahedral coordination of 4 anions has 93-95% the radius... 

Room temperature ionic liquids (RTILs) are molten salts whose melting points are below room temperature. RTILs are formed when the constituent ions are sterically mismatched, thereby hindering crystal formation [17]. As polar solvents, RTILs have unique applications as tunable and environmentally benign solvents with very low volatility, high fire resistance, excellent chemical and thermal stability and wide liquid temperature range and electrochemical windows [17-19]. Solvent applications of RTILs include, for example, organic synthesis [17,20, 21], separations [22, 23], storage and transportation of hazardous chemicals [24], polymeric electrolytes [25, 26], dissolution of natural products [27] and synthesis of hollow metal oxide microspheres [28]. 

To investigate the role of LCP in the composite on the electro-optical properties, PS[4BC/DM]s with the degree of polymerization of 12 and 40 were used as LCP. In order to investigate the role of LCD in the composite on the electro-optical effect, low molecular weight smectic LC, S2 was employed as a sample of composite in which any LCP was not included. S2 is a binary smectic mixture of low molecular weight liquid crystals as shown in Figure 1. The ionic impurities (Pt catalyst) of about 1000 ppm was added to S2 to unify the condition of electric current effect with the (PS[4BC/DM](n=12, 40)/E7) composites which contain about 1000 ppm of Pt catalyst. 

The book first focuses on commonly used industrial polymers, including polypropylenes, low- and high-density polyethylenes, and poly(vinyl chloride), as well as less widely used polymer types, such as acrylics, ether polymers, cellulosics, sulfide polymers, silicones, polysulfones, polyether ether ketones, and polybenzimidazoles. It then explores polymer derivatives and polymeric combinations that play special and often critical roles in diverse fields of human activities. The polymers covered include liquid crystal, electroactive, ionic, and shape memory polymers hydrogels and nanocomposites. The book concludes with a comprehensive overview of new developments in the use of polymers in a variety of areas. 

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