Structure, dynamics, and phase behaviors of novel quasi-coacervate gel composites

Traditional coacervates are dense liquid states composed of oppositely charged macromolecules formed via liquid-liquid phase separation. Here we report a novel system where charged macromolecules can simply complex with oppositely charged monomers to induce phase separation. Rich phase behaviors can be induced by tuning various parameters such as salt concentration and charge stoichiometry. When the charges of the monomers are more than the charges on the polymers, by tuning the salt concentration, there are three phase regimes. At low salt concentration, it is a phase-separated system; at high salt concentration, it is a one phase region where chains have single chain conformation. However, at intermediate salt concentration, there is an “emulsion suspension phase”, which contains stable self-assembled micelle-like structures with uniform size. More interestingly, in addition to the charged monomers, by adding extra neutral monomers and initiator, we can make gelation in the “emulsion suspension phase” so that the micelle-like structures can be trapped inside the gel mesh to function as “nanoreactors”. Such novel quasi-coacervate gel composites are complementary to the traditional coacervate systems.