A copolymer having segments of polyphenylene ether, styrene and/or acrylonitrile, a method for making the copolymer, and a blend of the copolymer with a styrenic resin are provided. The polyphenylene ether segments are derived from polyphenylene ether polymers having at least one end cap that a pair of unsaturated aliphatic carbon atoms, i.e. a carbon—carbon double bond. The copolymer is miscible with styrene/acrylonitrile copolymers.