Functionalized ethylene/α-olefin interpolymer compositions

A composition comprising:

• a multi-block interpolymer that comprises, in polymerized form, at least about 50 mole percent ethylene and one or more copolymerizable comonomers, and wherein said multi-block interpolymer comprises two or more randomly distributed segments, or blocks, differing in comonomer content, crystallinity, density, or melting point and wherein the multi-block interpolymer has a molecular weight distribution (Mw/Mn) from about 1.5 to about 3.5, and has an average block index greater than 0.1 to about 1.0;
• and
• wherein the multi-block interpolymer is functionalized with at least one compound selected from the group consisting of radically graftable unsaturated compounds containing at least one heteroatom.