Fluorescence behavior of an azobenzene-containing amphiphilic diblock copolymer

Abstract

The amphiphilic azobenzene block copolymer, poly(6-(4-phenylazophenoxy)hexylmethacrylate-b-poly((2-dimethylamino)ethyl methacrylate)) (P(PHMA)-b-P(PEGMA)) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization technique. The results showed that the polymerization was carried out in a controlled manner. The obtained amphiphilic block copolymer showed strong fluorescence emission in mixed water/tetrahydrofuran (THF) solution. The intensity of fluorescence emission was slightly changed after the solution was irradiated by UV-vis light. Further investigation showed that the copolymer emitted strong fluorescence in THF after UV-vis irradiation. The polymer solution was characterized by DLS and TEM. The results showed that the change of fluorescence emission behavior of the amphiphilic block copolymer both in water–THF and THF solution was caused by the formation and size change of aggregates originating from the photo-isomerization of azobenzene chromophore.