Acidic and basic methacrylate co- and ter-polymers based on (respectively) methacrylic acid (MAA) and dimethylaminoethyl methacrylate (DMAEMA) were prepared by solution free radical polymerization and structurally characterized by NMR spectroscopy and dilute solution viscometry. Relationships between pKa/pKb/pH, solubility and extent of ionization were determined by acid/base titration. Yields and equilibrium water contents of complex coacervates from these polymers were measured, and microcapsule forming systems based on this effect were developed as potential prostheses for organ transplantation. Short term cell viability in these capsules was demonstrated using erythrocytes as a model cell line.