Molecular Configurations of Vinyl Polymers with Strictly Regular Structures and Their Mean Dimensions and Electric Moments in Dilute Solutions

Neglecting the long‐range interaction between segments, general expressions for the mean dimensions and the electric moments of isotactic and syndyotactic vinyl polymers in dilute solutions are derived. For the comparison with experimental results, the following expression is employed for the potential energy of the hindered rotation around C–C links of a skeletal chain:

$${\mathrm{E=(E}}_0\text{/2)[1−}\cos {\mathrm{(\theta -\theta }}_0\mathrm{)],}$$

where θ is a twisted angle from the trans position with θ₀ as the most probable one, and E₀ is the maximum height of the potential energy. For simplicity numerical calculations of the electric moments are restricted to vinyl polymers in which the direction of the electric moment vector of each substituted group coincides with one of four symmetry axes of tetrahedral model of carbon atom. For isotactic polymers three cases are examined. The first: all C–C links are twisted in the same manner. The second: consecutive two C–C links are twisted to inverse directions to each other. The third: potential energies of the hindered rotation around C–C links have their minima at the same angles as in crystalline state. From consideration of the minimum distance between two adjacent substituted groups, it is concluded that, if the molecular dimension of isotactic polystyrene is not far apart from that of atactic polystyrene, the deformation of the second type would be less probable. When taken into account the collisions between different parts of the polymer molecule, the deformation of the third type or the other similar to it may be most probable. In this case when 〈R²〉/nb² is taken to be 12∼13, then 〈u²〉/Nu₀² should become 1.5∼1.7, N=n/2 being degree of polymerization. For syndyotactic polymers, two unknown parameters involved in the theory may be uniquely determined by measuring 〈R²〉/nb² and 〈u²〉/Nu₀².