Synthesis and electron transporting properties of triblock copolymers consisting of polyfluorene and polystyrene

Abstract

For the improvement of the electron transporting property of poly(9,9-di-n-octylfluorene) (PFO) as a conventional PLED material, well-defined triblock copolymers of PFO [Number-average molecular weight (Mn ) ≈ 10000] with different chain length polystyrene (PSt) (Mn ≈ 1000, 2000, and 3000) were synthesized via a combined synthesis strategy of Suzuki-Miyaura reaction, atom transfer radical polymerization (ATRP), and Steglich coupling reaction. Electron only (EO) devices for homopolymer and triblock copolymers were fabricated by a solution process. It was demonstrated that triblock copolymer (Mn,PSt ≈ 2000) after annealing exhibited the highest electron mobility. Thermal, optical, electrochemical and morphological properties were investigated severally and revealed that the microphase separated structure was formed in block copolymers (Mn,PSt ≈ 2000, and 3000) after annealing, and the introduction of PSt raised the glass transition temperature (Tg ) and deepened the LUMO level.

Emergent Dispersion and Sorting Behaviors of Carbon Nanotubes When Combining Short Conjugated Oligomers with Nonconjugated Coil Segments

“…One possible explanation for this difference in chirality selectivity can be attributed to a change in the overall polymer rigidity induced by the coil blocks. In fact, it is noted in the literature of triblock copolymers that the chain rigidity of the middle PFO unit increases (compared to PFO homopolymer) as evidenced by an increase in glass transition temperature ( T g ) with increasing PS length . We also observe a ∼ 8 °C increase in T g of PFO 16 in the triblock compared to the homopolymer (Figure S11).…”

“…In fact, it is noted in the literature of triblock copolymers that the chain rigidity of the middle PFO unit increases (compared to PFO homopolymer) as evidenced by an increase in glass transition temperature (T g ) with increasing PS length. 32 We also observe a ∼ 8 °C increase in T g of PFO 16 in the triblock compared to the homopolymer (Figure S11). This enhanced rigidity may cause a slight change in the triblock's preference favoring largerdiameter CNTs with smaller surface curvature.…”

Synthesis and Electron Transporting Properties of Diblock Copolymers Consisting of Polyfluorene and Polystyrene

“…Dry tetrahydrofuran (THF) and other reagents were commercial products from FUJIFILM Wako Pure Chemical Corporation in Osaka, Japan. α-monocarboxylic polystyrenes (PSt-COOHs) with number-average molecular weights ( M n ) of 750, 1250, and 1800 were synthesized according to our earlier reports [ 28 ].…”