Regular copolyamides. IV. Characterization of membrane morphology

Asymmetric copolyoxamide films prepared via a solution‐casting/gelation process have been characterized by scanning electron microscopy, small‐angle light scattering, and measurements of surface area and hydrophilicity. The polymer selected for study is a regular copolyamide prepared from N,N‐bis(2‐aminoethyl) oxamide and isophthaloyl chloride, and shows promise as a membrane material for desalination by reverse osmosis. Scanning electron microscopy reveals a unique capillary structure in films cast from N,N‐dimethylacetamide‐LiCl mixtures, plus a variety of structures in trifluoroacetic acid‐cast membranes. Light‐scattering experiments on water‐swollen films have substantiated microscopic observations of desiccated samples; the gel structures of the copolyoxamide films do not appear to suffer severe collapse on dehydration. Measurements of surface area and water sorption have been conducted in an attempt to assess membrane‐water interaction.