Polymers of anionically polymerized monomers such as mono-olefins, conjugated dienes, vinyl substituted aromatics, vinyl substituted pyridine, vinyl substituted quinolines, various aldehydes, various epoxides, various oxetanes, various oxygen-containing compounds, and the like are produced and end capped with a polyisocyanate or polyisothiocyanate having the formula R--(N.dbd.C.dbd.X).sub.n wherein R is a hydrocarbon, n is 2 or 3, and X is oxygen or sulfur. Such end capped polymers, of course, contain one reacted or connected isocyanate or isothiocyanate group and at least one free isocyanate or isothiocyanate end group, which free end group(s) reacts with an amide to give an imide end group. The imide terminated polymer is then hydrolyzed to form a stable amine terminated polymer. The reaction of the amide compound with the isocyanate(s) or isothiocyanate(s), followed by hydrolysis, results in the replacement of the free isocyanate or isothiocyanate end group(s) with an amine group(s). Thus, the amine terminated polymer contains the polymer connected to an isocyanate or isothiocyanate group (now an amide group or a thioamide group), which in turn is attached to the hydrocarbon portion, that is, the "R" portion of the polyisocyanate, which in turn is connected to the formed amine group. The amine terminated polymers may be stored extended periods of time and then reacted with various polymers, prepolymers, monomers, or various combinations thereof to form various block or graft copolymers. That is, the amine terminated polymer may be subsequently reacted with any amine reactive compound such as diepoxy monomers or an epoxy prepolymer in the presence of known epoxy catalysts to give a blocked epoxy copolymer. Similarly, the amine terminated polymer may be reacted with urea prepolymers or urea-forming monomers to yield a block urea copolymer. Reaction of the amine terminated polymer with urethane polymers, urethane prepolymers, or urethane-forming monomers will yield a urethane block copolymer. Reaction of the amine terminated polymer with urethane-urea prepolymers or urethane-urea forming monomers will yield a urethane-urea block copolymer. Similarly, various dianhydride and diamine monomers may be utilized to form an imide block copolymer.