Enhanced Energy Transfer Efficiency in Star-shaped Light-harvesting Block Copolymers Prepared by RAFT Polymerization

摘要

Reversible addition-fragmentation chain transfer(RAFT)polymerization has been used to synthesize a star-shaped light-harvesting polymer comprising six diblock copolymer arms of styryl coumarin(St-Coumarin)and methyl acrylate(MA)surrounding a ruthenium(II)trisbipyridyl energy trap core.The efficiency of excitation energy transfer from the styryl coumarin units to the Ru(II)core is increased to 90% compared to 60% for the analogous star polymer without MA blocks.The enhanced excitation energy transfer efficiency arises from the role of the MA blocks in diminishing the competitive quenching of photoexcited St-coumarin chromophores by dithiobenzoyl polymer end groups present from the RAFT polymerization procedure.