Stress-Optical Coefficient of Polymeric Networks. Stereo-irregular and Multirepeat Polymers

Expressions for the optical anisotropy ΔΓ of Kuhn's random link (an equivalent to the stress-optical coefficient) of stereo-irregular and multirepeat polymers are derived on the basis of the additivity principle of bond polarizabilities and the rotational-isomeric-state approximation for rotations about skeletal bonds. By multirepeat polymers we mean ones in which a stereochemically identical structure repeats along the chain at an interval of an arbitrary number of skeletal bonds. Expressions for the unperturbed mean-square end-to-end distance 〈r2〉, which are required in the calculation of ΔΓ, are also obtained. All expressions are cast into compact form by use of Flory and Jernigan's method. Comparison is made of expressions for 〉r2〉 derived in this paper, with those given previously by Flory and his co-workers and by the present author.