As is well known, liquid-liquid phase separation can occur either upon heating or cooling, corresponding to lower and upper critical solution phase boundaries, respectively. Likewise, self-assembly transitions from a monomeric state to an organized polymeric state can proceed either upon increasing or decreasing temperature, and the concentration dependent ordering temperature is correspondingly called the 'floor" or "ceiling" temperature. Motivated by the fact that some phase separating systems exhibit closed loop phase boundaries with two critical points, the present paper analyzes self-assembly analogs of reentrant phase separation, i.e., reentrant self-assembly upon varying the temperature. In particular, reentrant self-assembly transitions are demonstrated to arise in thermally activated equilibrium self-assembling systems, when thermal activation is more favorable than chain propagation, and in the case of equilibrium self-assembly near an adsorbing boundary, where a strong competition exists between adsorption and self-assembly. Apparently, a competition between interactions or equilibria generally underlies reentrant behavior in both liquid-liquid phase separation and self-assembly transitions.
Citation: Journal of Chemical Physics
Pub Type: Journals
self-assembly, reentrancy, adsorption, gelation, closed loop phase boundary