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Excitation migration dynamics and the energy-transfer process in a donor−acceptor pair system on photoexcitation have been investigated by using static and time-resolved photoluminescence (PL) measurements. The PL spectrum of poly(N-vinylcarbazole) (PVK) was fully superposed on the electronic absorption spectrum of poly(9,9‘-di-n-hexyl-2,7-fluorenylvinylene) (PDHFV) to fulfill a requirement for an efficient Förster-type energy transfer. In the PL spectrum of a blended PVK film with 0.5 wt % PDHFV on photoexcitation at 340 nm, the PL emission of PDHFV, which exhibits little absorbance at the excitation wavelength, prevailed over the PL emission of PVK. The PL spectrum of a bilayered structure with a PVK layer thickness of 4 μm and a PDHFV layer thickness of 80 nm, which was prepared by spin-casting PDHFV solution in trichloroethylene on a PVK film, also showed the PL emission of PDHFV on photoexcitation of the PVK layer at 340 nm without a trace of the PL emission of PVK. Excitation energy migration through a PVK bulk was observed up to a PVK thickness of 23 μm. A time-correlated single-photon counting (TCSPC) study deduced an energy migration velocity of 3.5 × 106 cm/s and a dwell time between each hopping of 85 fs, respectively, in the PVK bulk of the bilayered structures with a PDHFV layer thickness of 10 or 80 nm.

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Polyethylene-g-polystyrene (PE-g-PS) was synthesized as a compatibilizer for polypropylene/polystyrene (PP/PS) blends by the living radical polymerization of styrene with polyethylene-co-glycidylmethacrylate (PEco-GMA). The compatibilizer effect of PE-g-PS on the morphology and thermal properties of PP/PS blends was investigated. The crystalline temperature of PP in PP/PS blends decreased with increasing PE-g-PS contents. Morphologies of PP/PE-g-PS/PS blends showed much better dispersion of each domain for higher PE-g-PS contents. The molecular weight of PS segment in PP/PEg-PS/PS blend was increased by addition of styrene monomer during the post melt blending process where post living radical polymerization reaction proceeded.PE-g-PS as a Compatibilizer for PP/PS Blends / 61 FIGURE 4. Microphotographs of PP/PS (70/30 wt/wt %) blends (a) without compatibilizer, (b) with 5 phr compatibilizer, and (c) with 10 phr compatibilizer, respectively.

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