characteristic ratio in polymers

The ratio of the mean-square end-to-end distance, $< r 2 > 0$ , of a linear polymer chain in a theta state to $N · L 2$ , where $N$ is the number of rigid sections in the main chain, each of length $L$ ; if all of the rigid sections are not of equal length, the mean-square value of $L$ is used, i.e.

$L 2 = ∑ i L i 2 – N$

In simple single-strand chains, the bonds are taken as the rigid sections. The recommended symbol is: $C N$ ( $C ∞$ when $N → ∞$ ).

Source:

Purple Book, p. 49