We report the synthesis of polyurethaneurea elastomers containing 1,2,4,5-tetrazine covalently reacted within the main chains of the polymers. Our study investigates the synthesis of 3,6-diamino-1,2,4,5-tetrazine (DAT), the polymerization reaction conditions for reacting DAT into the backbone of segmented polyurethane elastomers, and the metal-complexation capabilities of tetrazine-containing elastomers with cobalt (II) chloride. Tetrazines are highly colored and electro-active heterocyclic moieties, which have a very high electron affinity which make them reducible at high to very high potentials. Upon complexation with metals, we observed a strong color shift of the polymers from deep red to blue indicating the binding efficacy for the polymers. We quantified the metal-complexation capability of the tetrazine elastomers and determined a molar ratio of approximately two metal atoms per tetrazine allowing us to provide a plausible complexation mechanism for the active polymers. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 3915-3922, 2009