Probing interchain interactions in emissive blends of poly [2-metboxy-5-(2′-ethylhexyloxy)-p-phenylenevinylene] with polystyrene and poly(styrene-co-2-ethylhexyl acrylate) by fluorescence spectroscopy

We present dynamic and static photoluminescence studies on polymer blends of conjugated poly [2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) with polystyrene-co-1-pyrenyl methyl methacrylate and its copolymer poly(styrene-co-2-ethylhexyl acrylate-co-1-pyrenylmethyl methacrylate) (with 9 mol% and 19 mol% of 2-ethylhexyl acrylate units and 0.06 mol% of 1-pyrenyl). Pyrenyl-labeled polystyrene and its copolymers were synthesized by emulsion polymerization and characterized by C-13 and H-1-NMR, FTIR, GPC, DSC, and UVVis. Spin-coating films of the blends were prepared from chloroform solutions with 0.1, 0.5, 1.0, and 5.0 wt% of MEH-PPV The miscibility of these systems was studied by non-radiative energy transfer processes between the 1-pyrenyl moieties (the energy donor) and MEH-PPV (the energy acceptor). The relative emission intensities and the fluorescence lifetimes of the donor showed that the miscibility of MEH-PPV and the copolymers is greater than that of MEH-PPV and polystyrene and this was confirmed by epifluorescence optical microscopy and scanning electron microscopy.