Diffusion properties of inkjet printed ionic self-assembling polyelectrolyte hydrogels

In the present work, Crank's model was used to characterize solute transport in inkjet printed polyelectrolyte gels. The diffusion of a small charged molecule (fluorescein), various size linear uncharged molecules (dextrans), and a globular protein (albumin) in printed PSS-PDDA with near stoichiometric composition happened respectively at about 10^-8, 10^-9, and 10^-10 cm²/sec. Polyelectrolyte complexes printed with non-stoichiometric ratios were found to be non-equilibrium structures consisting of three populations of polymer chains: fully complexed chains, chains in partial electrostatic interaction with the complex, and chains in excess having minimal interaction with the complex. This structure may be multiple phases. The applicability of hydrodynamic and free volume models to describe transport in printed polyelectrolyte gels was discussed.