Solvent effect on equilibrium organization of confined polymers.

Abstract

The equilibrium organization of two polymers in strong confinement has been extensively investigated in the scope of simple models in the recent past, after it was suggested that the entropic repulsion between polymers could be a mechanism for chromosome separation in living cells. Despite many efforts, how solvent quality can manipulate separation or compaction for the formation of domains in a two-polymer model system within symmetric or asymmetric confinement still remains elusive. This paper presents some important findings for a two-polymer system within box-like (symmetric) and triangle-like (asymmetric) confinement with equal areas, in terms of structural transitions such as from a single globule to individual globules, non-monotonic change in polymer size, variation in the free-energy barrier with separation, etc. By using the exact enumeration method on a two-dimensional self-avoiding walk model of polymers, our results reveal that the polymers have a greater preference to form individual globules rather than a 'micelle'-like single globule in triangular confinement compared to box-like confinement. Additionally, our results suggest that asymmetric confinement can act as an ideal tool to trap polymers in poor solvents due to the large free-energy barrier.