A method of making a hydrogenated nitrogen-containing copolymer, the method comprising: obtaining or providing a precursor copolymer that is a polymerized product of a monomer composition comprising butadiene, wherein the precursor copolymer is a random or block copolymer comprising 1) a hydrocarbon backbone, wherein the hydrocarbon backbone has carbon-carbon double bonds; 2) unsaturated pendant groups ∗ -CH=CH 2 attached to the hydrocarbon backbone, wherein the asterisk denotes the attachment site of the pendant group to the hydrocarbon backbone; and hydroformylating and reductively aminating the precursor copolymer in the presence of at least one transition metal catalyst to provide a first aminated copolymer, wherein the first aminated copolymer comprises 1) a hydrocarbon backbone, wherein the hydrocarbon backbone has carbon-carbon double bonds; 2) nitrogen-containing pendant groups attached to the hydrocarbon backbone, the nitrogen-containing pendant groups being of Formula and Formula ∗ -CH 2 CH 2 CH 2 -NR 1 R 2 *-CH(CH 3)-CH 2 -NR 1 R 2 wherein a) R 1 is hydrogen or alkyl and R 2 is an alkyl; or b) R 1 and R 2 together with the nitrogen to which they are both attached form a heterocyclic ring that is saturated, the heterocyclic ring optionally further comprising an oxygen heteroatom; wherein the molar ratio of pendant groups of Formula to pendant groups of Formula is at least 6; and subsequently adding a hydrogenation catalyst and hydrogenating the first aminated copolymer in the presence of the hydrogenation catalyst to provide the hydrogenated nitrogen-containing copolymer having pendant nitrogen-containing groups of Formula and. obtaining or providing a precursor copolymer that is a polymerized product of a monomer composition comprising butadiene, wherein the precursor copolymer is a random or block copolymer comprising 1) a hydrocarbon backbone, wherein the hydrocarbon backbone has carbon-carbon double bonds; 2) unsaturated pendant groups ∗ -CH=CH 2 attached to the hydrocarbon backbone, wherein the asterisk denotes the attachment site of the pendant group to the hydrocarbon backbone; and 1) a hydrocarbon backbone, wherein the hydrocarbon backbone has carbon-carbon double bonds; 2) unsaturated pendant groups ∗ -CH=CH 2 attached to the hydrocarbon backbone, wherein the asterisk denotes the attachment site of the pendant group to the hydrocarbon backbone; and hydroformylating and reductively aminating the precursor copolymer in the presence of at least one transition metal catalyst to provide a first aminated copolymer, wherein the first aminated copolymer comprises 1) a hydrocarbon backbone, wherein the hydrocarbon backbone has carbon-carbon double bonds; 2) nitrogen-containing pendant groups attached to the hydrocarbon backbone, the nitrogen-containing pendant groups being of Formula and Formula ∗ -CH 2 CH 2 CH 2 -NR 1 R 2 *-CH(CH 3)-CH 2 -NR 1 R 2 wherein a) R 1 is hydrogen or alkyl and R 2 is an alkyl; or b) R 1 and R 2 together with the nitrogen to which they are both attached form a heterocyclic ring that is saturated, the heterocyclic ring optionally further comprising an oxygen heteroatom; wherein the molar ratio of pendant groups of Formula to pendant groups of Formula is at least 6; and 1) a hydrocarbon backbone, wherein the hydrocarbon backbone has carbon-carbon double bonds; 2) nitrogen-containing pendant groups attached to the hydrocarbon backbone, the nitrogen-containing pendant groups being of Formula and Formula ∗ -CH 2 CH 2 CH 2 -NR 1 R 2 *-CH(CH 3)-CH 2 -NR 1 R 2 a) R 1 is hydrogen or alkyl and R 2 is an alkyl; or b) R 1 and R 2 together with the nitrogen to which they are both attached form a heterocyclic ring that is saturated, the heterocyclic ring optionally further comprising an oxygen heteroatom; subsequently adding a hydrogenation catalyst and hydrogenating the first aminated copolymer in the presence of the hydrogenation catalyst to provide the hydrogenated nitrogen-containing copolymer having pendant nitrogen-containing groups of Formula and.