The relationship between configuration and conformation of Stereoregular polymers is reviewed. The reason for the frequent occurrence of helical conformations in the solid state is discussed, as well as the difficulties encountered in the experimental investigation of the conformational equilibrium of macromolecules in solution. As far as the local conformation of the repeat units of polymers in solution is concerned, satisfactory information is available only in the case of isotactic poly(#x3B1;-olefins). This is mostly due to the successful combination of statistical mechanical calculations and experimental measurements of optical activity in isotactic poly(#x3B1;-olefins) containing asymmetric carbon atoms in the lateral chain. In this case optical activity measurements provide a demonstration of the existence of the short range helical order in solution. It is further shown that a series of independent experiments (including some recent end-to-end distance measurements) confirm the detailed picture of the macromolecule in solution which was obtained through conformational analysis and statistical calculations. The influence of the asymmetry of the repeat unit on the main chain conformation is discussed, with reference to the analogous situation in biopolymers. The problem of conformational transitions is also considered and the difference in behaviour between Stereoregular synthetic polymers and biopolymers is discussed. Conformational transitions are related to the existence of conformational rigidity in macromolecules, and the thermodynamic and kinetic bases of this latter phenomenon are discussed. Further analogies and differences between the conformational properties of Stereoregular synthetic polymers and biopolymers are considered. Finally, it is shown how the data obtained for isotactic poly(#x3B1;-olefins) can be generalized for understanding some of the basic features which characterize the conformation of macromolecules in solution.
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