Synthesis and characterization of polymethacrylates containing conjugated oligo(phenylene ethynylene)s as side chains

Abstract

In order to form suitable systems designed for resonance energy transfer, a series of monodisperse methacrylate-based monomers containing rigid π-conjugated oligo(phenylene ethynylenes) with different sizes of the conjugated systems (M1–M3), and therefore different optoelectronic properties, were synthesized and subsequently polymerized using the reversible addition–fragmentation chain transfer polymerization technique (P1–P3). In addition, these oligomers were also copolymerized with methyl methacrylate. The obtained polymers were characterized by 1H NMR spectroscopy, size exclusion chromatography, and analytical ultracentrifugation. The photophysical properties of the polymers were studied by UV–vis absorption and emission spectroscopy in diluted solutions as well as in thin films and compared to the photophysics of the corresponding monomers. Thereby, changes going from monomeric to polymeric systems could be detected in fluorescence quantum yields and lifetimes pointing to energy trapping, e.g., energy transfer. Donor–acceptor copolymers containing different numbers of monomeric units within the side chain exhibit differences in the emission spectra, indicating that energy trapping in polymers is very sensitive to structural properties such as the chain length. UV–vis absorption spectroscopy as well as time-resolved lifetime studies indicate intrapolymer and interpolymer energy transfer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012