Rod-like polymer

In Chapter 3 it was pointed out that certain rod-like polymers showed many of the attributes of liquid crystals in the melt. In particular, these molecules were oriented in shear to such an extent that interchain entanglement was small and the melts had a low viscosity. On cooling of the melt these rod-like molecules remained oriented, effectively self-reinforcing the polymer in the direction of flow. The essential differences in the properties of liquid crystal polymers... 

The structural chemistry of the organotin halides is dominated by their Lewis acid properties and their propensity to form five- and six-coordinate complexes. Self-association may give oligomers or polymers in the solid state, which usually dissociate in solution. The structure of tricyclohexyltin chloride in the crystal is temperature-dependent. At 108 K, it has the form of a rod-like polymer with distorted trigonal-bipyramidal tin and Sn-Cl separations of 245.6(7) and 300.77(7) pm, but at 298 K, the structure is best regarded as consisting of near-tetrahedral discrete molecules.3... 

A simple theory of the concentration dependence of viscosity has recently been developed by using the mode coupling theory expression of viscosity [197]. The slow variables chosen are the center of mass density and the charge density. The final expressions have essentially the same form as discussed in Section X the structure factors now involve the intermolecular correlations among the polyelectrolyte rods. Numerical calculation shows that the theory can explain the plateau in the concentration dependence of the viscosity, if one takes into account the anisotropy in the motion of the rod-like polymers. The problem, however, is far from complete. We are also not aware of any study of the frequency-dependent properties. Work on this problem is under progress [198]. 

Microcellular foaming, bimodal cell size distributions, and high open-celled contents of molecular composites of HT-polymers were reported by Sun et al. [33], investigating blends of a rod-like polymer polybenzimidazole with an aminated PSU and poly(phenyl sulfone) by using carbon dioxide as a blowing agent. The complex foaming behavior was related to phase separation within the otherwise... 

The structures of polymers containing benzobisthiazole and benzobisoxazole have been determined. These form rigid rod-like polymers with high specific strength <81MM935>. For some bis-selenadiazolo analogues of tetracyanoquinodimethane x-ray methods established the presence of extensive intermolecular interactions <87CL2285>. 

Rigid rodcrystallisation, 706 Rod climbing effect, 526 Rod-like molecules, 252 Rod-like polymer molecules, 274 Rod-shaped particle, 276 Rubber elasticity, 401 Rubbery plateau, 400 Rudin equations, 272 Rudin-Strathdee equation, 602 Rules of thumb for substituting an H-atom by a group X, 182... 

Intrinsic Viscosity - Molecular Weight Relationship. A rod-like polymer has a large a value in the Mark-Houwink equation (Eq. 25). Such an example is poly(y-benzyl L-glutamate)... 

One of the characteristic properties of rod-like polymers is that their concentrated solutions form lyotropic liquid crystals51. Such examples among synthetic polymers are polyamides52,53 and polyisocyanates54 which form cholesteric or nematic liquid crystals in selected solvents. 

Figure 28 Sketch of the formation of Langmuir Blodgett films using rod-like polymers.

In contrast to the situation with globular (bio)polymers, polarization of counterion atmospheres can be much better differoitiated for very elongated ellipsoidal or rod-like polymers. In many cases there is no interfering effect due to permanent dipoles. Even if these exist, they usually have sufficiently... 

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