Electronic energy transfer in pendant MEH-PPV polymers

Abstract

The synthesis of a series of polymers with appended pendant MEH-PPV oligomers of different conjugation length (trimer, tetramer and pentamer) is described. The synthesis involves RAFT polymerization of 4-chloromethylstyrene followed by coupling with the appropriate functionalized oligomer. The polymers have been characterized by GPC, UV-Vis and fluorescence measurements. The polymers exhibit a sequential red-shift in absorption and fluorescence spectra with increasing length of the MEH-PPV oligomer side chain. Temperature dependent measurements demonstrate that the non-mirror image relationship between absorption and fluorescence spectra in room temperature solutions can be attributed to the presence of torsional isomers in the side-chain chromophores. Efficient intramolecular energy transfer between the pendant chromophores is confirmed by fluorescence anisotropy measurements. The polymerization procedure outlined provides a useful template for providing polymers with tunable absorption and emission properties.