Abstract: An essentially isocyanate-free polyurethane polyurea polyethylenic oligomer is disclosed which is unusually strong and elastic. This oligomer is the reaction product of: (1) organic diisocyanate; (2) a stoichiometric deficiency of difunctional materials reactive therewith and consisting essentially of: (A) polyoxyalkylene glycol having a molecular weight of from 200 to 1000; (B) dihydric bisphenol-based alkylene oxide adduct containing from 2-10 alkylene groups per molecule; and (C) polyoxyalkylene diprimary amine having a molecular weight of from 150 to 800. In all of these, the alkylene groups contain from 2-4 carbon atoms. Components (A) and (B) are present in a weight ratio of from 1:4 to 9:1 and component (C) is present to supply from 30 to 60 equivalent percent of the total equivalents of component (2). The polyurethane polyurea so-constituted is capped with monohydric ethylenic compound, such as 2-hydroxyethyl acrylate, to provide a molecular weight in the range of about 5,000 to about 30,000.