An affinity membrane was designed for manufacturability, starting from novel polymer synthesis, through casting dope formulation, and finally membrane casting. Aldehyde functionality, introduced through acrolein, provided activation by Schiff base formation with proteins. Acrolein copolymers and their affinity applications were reviewed. Solution polymerization of acrolein and acrylonitrile produced a copolymer of sufficient mechanical strength to constitute a casting dope. Membranes cast from DMSO by the phase inversion process proved microporous when allowed to gel in warm (40-50 degrees C), humid air. Membranes cast from other solvents or at ambient temperature or those immersed directly under water were all tighter. No other supporting non-functional membrane was needed, although a scrim reinforcement improved robustness. Protein-binding studies using alkaline phosphatase enzyme and enzyme-linked immunoassay (ELISA) studies using an IgG antibody-antigen complex were conducted. After Various extensive washings to remove unbound protein, the polyaldehyde membranes were demonstrated to be comparable to the commercially available affinity membrane controls.