A new class of thermoplastics (dubbed "chimerics") is described that exhibits a high temperature glass transition followed by high performance elastomer properties, prior to melting. These transparent materials are comprised of cocontinuous phase-separated block copolymers. One block is an amorphous glass with a high glass transition temperature, and the second is a higher temperature phase transition block creating virtual thermoreversible cross-links. The material properties are highly influenced by phase separation on the order of 10-30 nm. At lower temperatures the polymer reflects the sum of the block copolymer properties. As the amorphous phase glass transition is exceeded, the virtual cross-links of the higher temperature second phase dominate the plastic properties, resulting in rubber-like elasticity. This article will particularly focus on plastics produced from phthalate-based polyester amorphous phases extended by urethane-derived second phases. Glass transitions from approximately 100-115 degrees C and subsequent elastomer phases to 150 degrees C are measured. The polymers exhibit high modulus (G' = I GPa), surprisingly high toughness (up to 2 times that of Bis-A polycarbonate) below the glass transition, and very high elongations and very low elastomer set subsequently. Materials are characterized by X-ray diffraction, DSC, AFM, dynamic mechanical spectroscopy, and tensile measurements. These materials may vastly simplify thermoplastic processes requiring high melt elasticity.