Figure 5.

Proposed model of shape anisotropy of a polymer at equilibrium based on the results of this paper and ref. 9. One can decompose a spherically symmetric polymer of given radius R into two (possibly overlapping) spheres of equal radius < R and “squeeze” all of the segments of the polymer into these two spheres. The loss in entropy caused by the longitudinal stretching and lateral compression of the polymer would be more than compensated by the appearance of new degrees of freedom, i.e., the relative separation between the two spheres and their relative orientation. This decomposition can be extended to three spheres, etc., until polymer deformation becomes entropically too unfavorable compared with the entropic gain caused by additional degrees of freedom.