  Critical fluctuations are known to induce a collapse of polymer chains in a
mixed solvent upon approaching its liquid-liquid critical point, as originally
predicted by Brochard and de Gennes. Recently, we have found that closer to the
critical point this collapse is followed by a reswelling of the polymer coils
well beyond the original dimensions, a phenomenon not predicted by the theory
of Brochard and de Gennes. We submit that upon approaching the critical
temperature more closely, the correlation length of the critical fluctuations
inside the polymer coils can no longer further increase due to the finite size
of the coils, resulting in the appearance of large critical Casimir forces that
cause a significant expansion of the polymer coils. Eventually, micro-phase
separation inside the coils will appear and the coils will reshrink. This
entire process takes place while the bulk solution is still in the one-phase
region.
