INDEX electrically conducting polymers

Liquid crystal polymers (LCP) are polymers that exhibit liquid crystal characteristics either in solution (lyotropic liquid crystal) or in the melt (thermotropic liquid crystal) [Ballauf, 1989 Finkelmann, 1987 Morgan et al., 1987]. We need to define the liquid crystal state before proceeding. Crystalline solids have three-dimensional, long-range ordering of molecules. The molecules are said to be ordered or oriented with respect to their centers of mass and their molecular axes. The physical properties (e.g., refractive index, electrical conductivity, coefficient of thermal expansion) of a wide variety of crystalline substances vary in different directions. Such substances are referred to as anisotropic substances. Substances that have the same properties in all directions are referred to as isotropic substances. For example, liquids that possess no long-range molecular order in any dimension are described as isotropic. 

Examples of such properties are conductivity, refractive index, electrical moment, dielectric constant, chelate formation, ion dissociation, phase transitions, solubility, and viscosity. Certain physical changes that occur when the photochromic entity is chemically attached to the macromolecular backbone of polymers are of special interest (see Chapter 1, Volume 2). 

Although many polymer properties are greatly influenced by molecular weight, some other important properties are not. For example, chain length does not affect a polymer s resistance to chemical attack. Physical properties such as color, refractive index, hardness, density, and electrical conductivity are also not greatly influenced by molecular weight. 

There are various methods of the glass transition temperature evaluation based on temperature dependence of polymer physical properties in the interval of glass transition 1) specific volume of polymer at slow cooling (dilatometric method) 2) heat capacity (calorimetric method),3) refraction index (refractometric method) 4) mechanical properties 5) electrical properties (temperature dependence of electric conductivity) or maximum of dielectric loss 6) NMR ° 7) electronic paramagnetic resonance, etc. 

Fig. 6.9 Functional polymer nano-composites left, well-dispersed Ti02 nano-particles in a polystyrene matrix for increasing the composite s refractive index, right, percolating carbon-black nano-particles in a carbonate matrix to realize an electrically conducting material...

Quite surprisingly, it turns out that a few non-linear equations have analytical and simple solutions. One of such cases is a soliton, i.e. a solitary wave (a kind of hump). Today solitons already serve to process information, thanks to the nonlinear change of the refractive index in a strong laser electric field. Conducting polymers turn out to be channels for another kind of solitons (cf. Chapter 9). 

Conjugated polymers (143) have also been prepared via coordination of iron(II) to dUithio >i5(3-hexyl-4-methylcyclopentadienide)arylenes (142) (Scheme 38)." " The weight average MW of these polymers were between 42,000 and 52,600 with polydispersity index (PDI) values ranging fiom 10.5 to 14.6. Oxidation of these polymers resulted in electrical conductivities ranging from 10 to 10 S/cm. 

Depending on the physical properties and size of fillers, the behavior of particle-filled suspensions and filled polymer compounds change. Such properties primarily include particle density, shape, and interaction. To these might be added particle hardness, refractive index, thermal conductivity, electrical conductivity, and magnetic properties. 

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