Controlling the Chain Orientation and Crystal Form of Poly(9,9-dioctylfluorene) Films for Low-Threshold Light-Pumped Lasers

Wang, Junjie; Liu, Yuchao; Zou, Deyue; Ren, Zhongjie; Lin, Jie; Liu, Xingyuan; Yan, Shouke

doi:10.1021/acs.macromol.0c02815

Cited by 7 publications

(5 citation statements)

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“…PFO exhibits polymorphic behavior and is a desirable laser medium. 51 As mentioned earlier, the coplanar β conformation is a characteristic feature of PFO. This conformation can be observed through UV-Vis absorption and fluorescence spectroscopy, and has therefore garnered significant interest in both solution and film studies.…”

Section: Influence Of Concentration On the Photophysical Properties O...mentioning

confidence: 80%

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Concentration effect on the chain structure and photoelectric properties of conjugated polymer precursor solutions and thin films: A mini review

Zhang,

Cheng,

et al. 2023

Journal of Polymer Science

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Conjugated polymers have attracted extensive attention in numerous research fields because of their exceptional photoelectric properties and distinctive solution processing capabilities. The conformation of the chain and the structure of the condensed state in solution are closely related to various factors, such as concentration and solvent. Concentration, as a significant external parameter, plays a crucial role in the self‐assembly and formation of crystalline structures in conjugated polymers. It also affects the properties of the solution, the structure of the membrane, and the performance of the fabricated devices. Recently, there have been an increasing number of studies conducted from the perspective of solution concentration. Therefore, it is important to comprehensively summarize the effect of concentration on the transition process of chain structure from solution to film, as well as the impact of concentration on the performance of related devices. In this review, we summarize the effects of concentration on the chain motion, particle size, ordered structure, and photoelectric properties of conjugated polymers in solutions and thin films, as well as on device efficiency. This provides a unique perspective on the fundamental characteristics of conjugated polymers, which can assist in the development and improvement of optoelectronic devices.

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Section: Influence Of Concentration On the Photophysical Properties O...mentioning

confidence: 80%

“…PFO exhibits polymorphic behavior and is a desirable laser medium 51 . As mentioned earlier, the coplanar β conformation is a characteristic feature of PFO.…”

Section: Influence Of Concentration On Polyfluorenes In Solution Film...mentioning

confidence: 88%

Concentration effect on the chain structure and photoelectric properties of conjugated polymer precursor solutions and thin films: A mini review

Zhang,

Cheng,

et al. 2023

Journal of Polymer Science

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“…Highly oriented PLLA and PDLA thin films were prepared according to the melt-draw technique, which has been frequently used for getting highly oriented ultrathin films. − During the melt-draw procedure, a small amount of 0.6 wt % polymer solution in DMF was first poured on a preheated glass plate at specified temperatures ranging from 152 to 180 °C and spread uniformly by a glass rod. After evaporation of the DMF solvent, the thin molten polymer layer was then picked up by a motor-driven cylinder with a draw speed ranging from 5 to 45 cm/s.…”

Section: Experimental Sectionmentioning

confidence: 99%

Structure and Mechanical Property of Melt-Drawn Oriented PLA Ultrathin Films

et al. 2021

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Ultrathin poly(lactic acid) (PLA) films have been prepared by a melt-draw technique, and their structures and mechanical properties have been studied by atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and tensile test. It is found that the meltdrawn PLA films consist of highly oriented granular α microcrystallites. The draw rate and temperature exhibit a synergistic effect on regulating the structures, including crystallinity and chain orientation, of the melt-drawn films. Post-thermal annealing leads to a structure reorganization from granular into lamellar structures with enhanced crystallinity up to about 55%. It also increases the chain orientation in the amorphous region, while the orientation status of chains in the crystalline phase remains almost unchanged because its orientation function in the as-prepared samples already close to 1. Mechanical tests of the melt-drawn poly(L-lactic acid) films illustrate a tremendous enhancement in mechanical properties of oriented PLA films compared to their nonoriented counterpart. The highest Young's modulus and tensile strength achieved for the sample prepared at 180 °C under a draw rate of 45 cm/s are about 1.3 and 2.5 times higher than those of its nonoriented counterpart.

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“…In addition, Ru et al have demonstrated the direct melt crystallization of β-PLLA under shear and pressure fields, while Bao et al reported that supramolecular PLLA bonded by multiple hydrogen bonds could crystallize preferentially in its β form at low crystallization temperatures. The γ form that has an orthorhombic unit cell packed by two 3/1 helical chains with the parameters a = 9.95 Å, b = 6.25 Å, and c = 8.8 Å has been produced by an epitaxial technique, which is a widely used method for regulating crystal modification as well as chain orientation of polymers including PLLA. − …”

Section: Introductionmentioning

confidence: 99%

Structure Evolution of Oriented Poly(l-lactic acid) Ultrathin Films during Deformation

et al. 2022

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Poly(L-lactic acid) (PLLA) ultrathin films with a highly oriented chain-fold lamellar structure in its α phase with a 10/3 helical chain conformation were prepared by a melt-draw technique. The structure evolution of the oriented α PLLA films during deformation along the original chain direction was studied by electron microscopy combined with electron diffraction and Fourier transform infrared (FTIR) spectroscopy. The results clearly illustrate that further deformation always enhances the orientation of chain segments in amorphous regions regardless of the draw ratio, which reduces slightly after thermal annealing, whereas the orientation status of chains in the crystalline phase is less affected owing to their already perfect alignments. Moreover, the combined results of electron diffraction and FTIR demonstrate that stretching the oriented thin film up to a draw ratio of λ = 1.5 reduces the crystallinity of α PLLA due to the distortion of pre-existing crystals and transition of 10/3 helical chains into 3/1 ones of some chain segments. The packing of 3/1 helical chains characteristic of the β form PLLA into an ordered crystal unit cell is, however, not realized even after thermal annealing. Further stretching up to λ = 2 results in the formation of β crystals, which are perfected by annealing at 150 °C but melt and recrystallize into oriented α crystals again after annealing at 175 °C. These results clearly shed more light on the strain-induced α-β transition of oriented PLLA thin films.

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Controlling the Chain Orientation and Crystal Form of Poly(9,9-dioctylfluorene) Films for Low-Threshold Light-Pumped Lasers

Cited by 7 publications

References 50 publications

Concentration effect on the chain structure and photoelectric properties of conjugated polymer precursor solutions and thin films: A mini review

Concentration effect on the chain structure and photoelectric properties of conjugated polymer precursor solutions and thin films: A mini review

Structure and Mechanical Property of Melt-Drawn Oriented PLA Ultrathin Films

Structure Evolution of Oriented Poly(l-lactic acid) Ultrathin Films during Deformation

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