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Phase separations in conjugated polymer (MEH-PPV) and non-conjugated polymer (PMMA) are studied by a near-field scanning microscopy and spectroscopy. Micron scale binary decomposition without photoluminescence spectrum shift occurs when the blending ratio (MEH-PPV/PMMA) is larger than one. When the ratio is smaller, the film becomes homogeneous and an ∼100 nm blue shift of PL spectrum happened. The new PL spectrum indicates the excitons in MEH-PPV chains are interrupted by the PMMA, and thus emitting light as PPV oligomers.