Statistical models of hydrated polymer chains

Let if be the number of pearls that consist of a number C of contiguous repeat units, and let be the number of swollen hydrated coils of the length f connecting them. Chain conformation is specified by the indices i = /i,/2, - and j = as shown in 

15 Sequential hydration along the polymer chain, with the end-to-end vector R under tension f, due to the cooperative interaction between the nearest-neghboring bound water molecules. The vector connects the incoming and outgoing point of a globule, while the vector is the end-to-end vector of a hydrated coU. (Reprinted with permission from Ref. [30].) 

The combinatorial factor co is the number of different ways to place the sequences specified by (i, j), and is given by 

This method is generally applicable to any chain along which two different structures are alternately formed [30]. 

For the statistical weight r] a swollen random coil, we can incorporate the cooperativity of H-bonds by assuming the Zimm-Bragg form (1.91) 

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