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region where the polymer is long enough to satisfy the RC model (the coil
limit). The figure below illustrates this for the radius of gyration R
G
):
In the WLC model the polymer is considered as a long, cylindrical chain with
uniform thickness. The diameter (d) is negligible compared to the length of the
chain (L). In addition, the chain has a constant curvature, but the direction of
the curvature is random. Wikipedia (Nov. 2012) provides a good description:
The WLC model envisions an isotropic rod that is continuously flexible. This is
in contrast to the freely-jointed chain model that is flexible only between
discrete segments. The worm-like chain model is particularly suited for
describing stiffer polymers..
log R
G
log M
Rod limit:
slope: 1.0
Coil limit
slope: 0.5
Figure 50