Semi-alicyclic polyimides as potential membrane oxygenators: Rheological implications on film processing, morphology and blood compatibility

Two polyimide structures were prepared from an alicyclic dianhydride and aromatic diamines, containing or lacking fluorine, and were tested as potential membrane oxygenators. First, the solution rheological properties were investigated to evaluate their effect on film processing by tape casting. Velocity and shear rates profiles were simulated to determine the shearing conditions during tape casting and transfer them in the flow curves. Proper films were obtained at a viscosity corresponding to a concentration in entangled regime, where pseudoplastic behavior is still noticed at shear rates beneath the blade. Theoretical predictions of gas permeability indicated a good oxygen (O2) exchange and carbon dioxide (CO2) removal through the studied polymers. Atomic force microscopy (AFM) scans revealed a morphology characterized by an intrinsic porosity. The pore size, uniformity and size distribution was affected by the structure of the diamine moiety. The interactions of blood with polyimide films indicated no prevalent adhesion of cells or plasma proteins. The results showed that the examined samples have adequate properties for potential membrane oxygenator applications.