Linear thermotropic polymers

Wunderlich, B. and Baur, H. Heat Capacities of Linear High Polymers. Vol. 7, pp. 151-368. Wunderlich, B. and Grebowicz, J. Thermotropic Mesophases and Mesophase Transitions of Linear, Flexible Macromolecules. Vol. 60/61, pp. 1-60. 

The order and mobility of a labeled flexible alkyl spacer in the linear thermotropic polymeric nematic liquid crystal poly(2,2 -dimethyl-4,4 -dioxyazoxybenzenedodecanedioyl-dj0) (poly[oxy(3-methyl-1,4-phenylene)azoxy 2-methyl-1,4-phenylene)oxy(1,12-dioxo-1,12-dodecanediyl-d2oll) is explored with deuterium NMR. The quadrupol splittings of the spacer methylene segments in the nematic melt of the polymer are reported as a function of the temperature and are contrasted with observations on model compounds solubilized in a nematic solvent. 

The term mesogenic group , for the purposes of this review, refers to the part of the polymer chain that is composed of the rigid, linear segments and the atoms or functional groups which link them together in a linear array. It is this part of the polymer chain that ultimately determines whether or not the polymer will be liquid crystalline, within what range the transition temperatures will occur for a thermotropic polymer, and what type of mesophase can be formed. 

New Engineering Thermoplastics New High Performance Thermosets Thermotropic Liquid Crystals Lyotropic Liquid Crystals Molecular Composites Advanced Composites Non-Linear Optical Polymers Electronically Conducting Polymers... 

In the experimental study of the optical properties of molecules by the method of flow birefringence (FBF), the question of the molecular dispersion of the solution is always important, particularly in the analysis of the properties of mesogenic macromolecules. The complex structure of thermotropic polymers and their tendency to form supermolecular structures require special monitoring of possible association or decomposition of the macromolecules in solution. The linear dependence of An in a wide range of rate gradients (Figs. 3.7 and 3.8) and... 

The mechanical properties can be studied by stretching a polymer specimen at constant rate and monitoring the stress produced. The Young (elastic) modulus is determined from the initial linear portion of the stress-strain curve, and other mechanical parameters of interest include the yield and break stresses and the corresponding strain (draw ratio) values. Some of these parameters will be reported in the following paragraphs, referred to as results on thermotropic polybibenzoates with different spacers. The stress-strain plots were obtained at various drawing temperatures and rates. 

Hydroquinone(HQ) or a naphthalenediol in the above reactions can be replaced with other diols such as biphenols and bisphenols. In the same manner, other dicarboxylic acid such as cyclohexane dicarboxylic acid, isophthalic acid, naphthalene dicarboxylic acids can be used in place of terephthalic acid. Of course, these substitutes should not destroy the linearity of the polymer chains if one is to obtain thermotropic compositions. 6-Hydroxy-2-naphthoic acid is a substitute for 4-hydroxybenzoic acid in Reactions 18 and 19. 

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