Renewable resource-based poly (m-phenylenevinylene)s and their statistical copolymers:: Synthesis, characterization, and probing of molecular aggregation and Forster energy transfer processes

We report a novel poly (m-phenylenevinylene)s and their copolymers based on renewable resource starting material 3-pentadecylphenol to trace the Forster energy transfer process and molecular aggregation in the pi-conjugated polymers. The new bisylide monomer was polymerized with bisaldehyde (or benzaldehyde) under Wittig-Horner reaction conditions to prepare poly 1(4-methoxy-6-pentadecyl-1, 3-phenylenevinylene)-alt-(1, 3-phenylenevinylene)] (M-PPV) and its para-counterpart poly L(4-methoxy-6-pentadecyl-1, 3-phenylenevinylene)-alt-(1, 4-phenylenevinylene)] (p-PPV) and oligo-phenylenevinylene model compound 4-methoxy-6-pentadecyl-1, 3-distyrylbenzene (OPV). A series of with m- or p-conjugated segments were also prepared by varying the m- and p-content from 0 to 100% in the feed. The selective excitation of m-conjugated segments in the copolymer by 310 nm light showed emission properties of pure p-conjugated segments indicating the efficient Forster energy transfer process in segmented copolymers. Both solution quantum yields and the emission intensities increase up to 75% of para-content in the copolymers. In the solid state, the increase in the p-incorporation in the copolymer decreases the photoluminescent intensity almost by four times as compared to that of pure meta-substituted PPV. The excitation spectra of the polymers confirmed a new peak at 400 nm corresponding to the aggregated polymer chains in the film, which is absent in the solution. (C) 2008 Wiley Periodicals, Inc.