Polymer nomenclature conformation

Having reduced the problem of polymer nomenclature to one of source nomenclature, it is now necessary to choose one of the established systems of naming organic compounds. Chemical Abstracts has long set the standard for systematic chemical nomenclature for indexing purposes, which at the same time conforms to accepted... 

Syndiotactic polystyrene (sPS) is a semicrystalline polymer, which shows four different forms, namely, a, [>. y, and <5, according to the nomenclature proposed by Guerra et al.41 The first two forms, a and />. have a //Y/n.v-planar conformation of... 

The conformational statistics of asymmetric vinyl chains such as P2VN are well-known 126). The rotational conformers of isotactic (meso) dyads are entirely different from those of syndiotactic (dl) dyads. Frank and Harrah132) have described each of the six distinct conformers for meso and dl dyads, using the t, g+ and g nomenclature of Flory 126). Excimer-forming sites (EFS) are found in the tt and g g+ meso states, and in the degenerate tg , g t dl state. Because the rotational conformers of compounds such as l,3-bis(2-naphthyl)propane do not match those of either the iso-or syndiotactic dyads of P2VN, the propane compounds make poor models of aryl vinyl polymers. However, the rate constants of fluorescence and decay of the intramolecular excimer in polymers can usually be determined from the propane compounds (but see the exceptional case of PVK and its models133)). 

FIGURE 10.19 Conformation of adsorbed polymer molecules with adsorption nomenclature (a) sin e point attachment, (b) loop adsorption, (c) flat multiple site attachment, (d) multilayer adsorption, (d) random coil, (e) nonunifiirm segment density distribution. 

In aqueous acetone 9S3 reacts with [AuCl(thiodiglycol)] to give [AuCl(9S3)], [141]. This oligomeric compound features square planar coordination at the Au atoms. Each Au binds to one S atom from a 9S3 molecule, which must twist into a strained conformation ([225] in the nomenclature of Dale) [76]. Trans to this S atom lies the CP. Bonds to two trans Au atoms completes the AuSClAu2 coordination sphere about any given Au ion, and results in a nearly linear infinite polymer. NMR studies in solution indicate interaction of the Au ion with three S atoms that are equivalent on the NMR time scale (at least down to 240 K). 

In solution, polysaccharide linkages between the individual monomers take conformations and energies according to the Boltzmann distribution. The nomenclature of the resulting random coils is that of classical polymer theory, with the major descriptor of the shape being the characteristic ratio, Coo- The ratio is proportional to the mean square end-to-end distance, normalized for the length of the individual monomeric residues. In the solid state, the polysaccharides often form crystallites that are too small to provide sufficient diffraction information for a full determination of their structure. However, they often yield fiber diffraction patterns that give useful clues to the correct structure. 

---