Polymer blends containing the title random copolymers, which the monomers (N-ethylcarbazol-3-yl)methyl methacrylate (NECMM) and 2-[(3,5-dinitrobenzoyl)oxy]ethyl methacrylate (DNBM) were introduced to provide charge-transfer (CT) interactions within the copolymer blends, were prepared as a model system. This PMMA/PMMA based blend serves as a model for CT compatibilization of other, incompatible, blends. Poly(NECMM-co-MMA) copolymers were blended with poly(DNBM-co-MMA) copolymers containing similar acceptor mole fractions and with D-A. ratios of unity. Single T-g’s initially found for the blends (all compositons and molecular weights) : indicated that all of the blends were compatible. Polymer blends which utilized acceptor copolymers-which had peak molecular weights (versus PS standards) around 30 000 were thermodynamically compatible while similar blends prepared with acceptor copolymers with peak molecular weights 3 times larger were kinetically compatible but thermodynamically incompatible. These phase separated after being heated above 200 degrees C. Almost all of the blends exhibited endothermic transitions at this temperature, previously attributed to the decomplexation of the CT pairs, but only the blends containing high molecular weight components possessed LCSTs. These transitions are thus attributed to the "unlocking" of conformationally-constrained polymer segments at the so-called "decomplexation" temperature.