Confined space and effective interactions of multiple self-avoiding chains

We study the link between three seeming-disparate cases of self-avoiding polymers: strongly overlapping multiple chains in dilute solution, chains under spherical confinement, and the onset of semi-dilute solutions. Our main result is that the free energy for overlapping $n$ chains is \emph{independent} of chain length and scales as $n^{9/4}$, slowly crossing over to $n^3$, as $n$ increases. For strongly confined polymers inside a spherical cavity, we show that rearranging the chains does not cost an additional free energy. Our results imply that, during cell cycle, \emph{global} reorganization of eukaryotic chromosomes in a large cell nucleus could be readily achieved.