Novel amphipathic photoluminescent copolymers containing fluorene, pyridine and thiophene moieties: Synthesis, characterization and self-assembly

In order to investigate the explicit electro-optical properties and self-assembly variations of the photoluminescent polymer with sterically hindered side chains, two novel polymers (P0 and P1) based on fluorene, pyridine and thiophene moieties were successfully synthesized through Suzuki coupling reaction. The molecular structures of the polymers were fully characterized by ¹H NMR, ¹³C NMR, elemental analysis and gel-permeation chromatograph, respectively. The photophysical properties, energy band gap and self-assembly behaviors of polymer P0 and P1 were examined through UV-vis absorption, photoluminescent spectra, cyclic voltammetry, dynamic laser light scattering and transmission electron microscopy. The experimental results indicated that the polymers took on wide band gaps of 3.09 and 3.11 eV with blue-green emission in thin solid films. By combining supramolecular assembly nature of hydroxy, phenolic and pyridyl units with controlled micro-phase separation of well-defined amphipathic di-block copolymers, we have obtained stable vesicles from the fluorescent amphipathic polymers in aqueous solution. The size and morphology of the vesicles formed can be effectively tuned in a range of 1144 nm-291 nm. This work can serve as an excellent exploratory example for the fine self-assembly control principle in the amphipathic photoluminescent copolymer with sterically hindered side chains through the multiple weak interactions of the π-system.