The invention relates generally to polymers and copolymers comprising N-vinylamide-type monomers, their preparation, and compositions, such as electrophoresis separation media, containing the same; to supports, such as capillaries, containing these polymers; and methods for separating a mixture of biomolecules, especially polynucleotides, using capillary electrophoresis. Separation media comprising such polymers yield advantageous performance in the analysis and separation of biomolecules by capillary electrophoresis.