Fluorescent nanostructures from aromatic diblock copolymers via atom transfer radical polymerization

Well-defined fluorophore (anthracene or pyrene) containing copolymers were synthesized via atom transfer radical polymerization (ATRP) using methyl methacrylate (MMA) and fluorophore bound methacrylate (AntMA or PyMA). The copolymers exhibited clearly distinct thermal and optical properties, in terms of glass transition temperature (T_g) and emission spectrum, depending on the polymer structures. Moreover self-assembly properties of the copolymers affected the formation of the polymer nanostructures at condensed phase, to distinguish the random against block copolymers. The antracene containing random copolymer had a single T_g value while antracene containing block copolymer had two T_g values. In addition, sharp fluorescence peaks (398, 416 and 439 nm) werer observed in the random copolymer of antracene. In contrast, the anthracene containing block copolymer showed a broad tailing of the peak reaching ∼550 nm. Interestingly, the copolymers having both randomly distributed anthracene units and consecutively connected pyrene units exhibited sharp emission at 398, 416, and 442 nm originated from the antracene unit and pyrene excimer emission at 482 nm. More importantly, well ordered nanopore films and nano scale micelle structures, originated from the self-assembly of antracene or pyrene block unit, were formed in block copolymers, while any type of an ordered structure was not found from the random copolymers. Therefore fluorescent nanostructures could be well-controlled by the polymers structures containing antracene and pyrene units, which might be widely useful for the development of novel photonics, optoelectronics, and sensor devices.