Copolymers comprising ethylene and propylene and methods for producing such polymers are provided. The polymers are blocky copolymers having semicrystalline ethylene sequences and amorphous or low crystallinity propylene sequences. The polymers are preferably prepared using metallocene-based catalyst systems but without the use of a chain shuttling agent. The polymers may have higher melting temperatures than previously known random copolymers or blocky copolymers prepared with chain shuttling agents having similar comonomer contents. The polymers include both ethylene-rich and propylene-rich copolymers.