Pseudostereochemical equilibrium

The conformation of atactic polymers, with any value of the m/r ratio, must be treated as that of a copolymer, wherein the monomer unit statistics are compounded with those of the rotational states. In this case we may either refer to Monte-Carlo type procedures, as done by Floiy, Mark, and Abe (194), or to the pseudostereochemical equilibrium method used by Allegra (195) and Briick-ner (196). In the latter case the atactic polymer is formally considered as a homopolymer that may assume the conformations of either the m or r dyads, with suitable adjusted statistical weights. 

Both these polymers have an - A-B structure [14,15], so their characteristic ratio C(q) was obtained through the procedure outlined in Section 2.1.2 see Eqs. (2.1.33H21.35) in particular. Since we were interested in stereoirregular (i.e., atactic) polystyrene for comparison with experimental data, the matrix procedure based on parameters proposed by Yoon, Sundararajan, and Flory [111] was suitably complemented with the pseudostereochemical equilibrium algorithm, which allows units of opposite configuration to be formally interconvertible with fixed relative amounts [36]. In the temperature range 30-70 °C the results may be fairly well expressed by the following analytical forms ... 

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