Study of Complex Coacervation in Low Concentration by Virial Expansion Method. I. Salt Free Systems

Abstract

Complex coacervation is explained with the assumption that the symmetrical aggregate polymer (SAP) model is applicable to both dilute and concentrated phases. An interaction potential between SAP's is obtained in a way similar to the derivation of the Flory-Krigbaum potential between usual polymers. Using this potential, osmotic pressure P is obtained by the virial expansion method. The curve of P (vs volume fraction of SAP) corresponds to the curve of pressure (vs volume) representing gas-liquid phase separation. Moreover the self-suppression is quantitatively explained by the contraction of SAP dimension.