A non-equilibrium approach for polymer solutions

We extend the Gaussian self-consistent method, earlier developed for a sing le polymer chain, to arbitrary number of chains in a dilute or semidilute s olution, It is also straightforward to consider in this framework copolymer solutions, and thus the method is quite general. Importantly, it permits a complete study of the equilibrium thermodynamic functions and kinetics of conformational changes within the same theoretical treatment. We find that within the two-phase coexistence region there are additional metastable sta tes of mesoglobules composed of a number of distinct chains, We argue that this can explain a recent experimental observation of small globular aggreg ates with a relatively monodisperse size in a dilute aqueous solution of PN IPAM. Turning to copolymer solutions we find that the mesoglobules may beco me thermodynamically stable in a narrow region of the phase diagram.